A vital part of PIPAC’s package of services is basic and applied research conducted independently or in cooperation with client companies.
Institute Personnel and their Research Interests
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Armando Victor M. Guidote, Jr., Ph.D.
Research Interests:
Organic Chemistry, Natural Products, Chemistry Education
Click here to see the list of his publications.
Armando Jerome H. de Jesus, Jr., Ph.D.
Research Interests:
Molecular dynamics simulations, Membrane-protein interactions, Membrane protein-small molecule interactions
Click here to see the list of his publications.
Ronaldo M. Fabicon, Ph.D.
Research Interests:
Industrial Chemistry
Click here to see the list of his publications.
Crisanto M. Lopez, Dr.rer.nat
Research Interests:
Infection Biology, Fungal Biotechnology
Click here to see the list of his publications.
Giselle Grace F. Lim-Co Yu Kang, Ph.D
Research Interests:
Biochemistry, Enzymes, Analytical Chemistry
Click here to see the list of her publications.
Gilbert U. Yu, D.Eng
Research Interests:
Materials Science (Polymers and Supramolecules), Chemical Education, Development of Lab Experiment Modules
Click here to see the list of his publications.
Ian Ken D. Dimzon, Ph.D
Research Interests:
Applied Analytical Chemistry, Mass Spectrometry, Chemical Metrology
Click here to see the list of his publications.
Anna Carissa M. San Esteban, Ph.D
Research Interests:
Electrochemistry (corrosion, electrocatalytic processes); Coordination Chemistry (coordination polymers, metal-organic frameworks)
Click here to see the list of her publications.
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Selected Publications
2020
Noriyuki Suzuki; Daisuke Mizuno; Armando M. Guidote Jr.; Shun Koyama; Yoshiro Masuyama; Masahiro Rikukawa
Asymmetric Reactions in Water Catalyzed by L-Proline Tethered on Thermoresponsive Ionic Copolymers Journal Article
In: Letters in Organic Chemistry, vol. 17, no. 9, pp. 717-725, 2020, ISSN: 1570-1786.
Abstract | Links | Tags: asymmetric aldol reaction, L-proline, michael addition, poly(N-isopropylacrylamide), polymer micelle, reaction in water, thermoresponsive polymer
@article{Suzuki2020,
title = {Asymmetric Reactions in Water Catalyzed by L-Proline Tethered on Thermoresponsive Ionic Copolymers},
author = {Noriyuki Suzuki and Daisuke Mizuno and Armando M. Guidote Jr. and Shun Koyama and Yoshiro Masuyama and Masahiro Rikukawa},
url = {http://www.eurekaselect.com/node/174298/article},
doi = {10.2174/1570178616666190819141307},
issn = {1570-1786},
year = {2020},
date = {2020-09-07},
journal = {Letters in Organic Chemistry},
volume = {17},
number = {9},
pages = {717-725},
abstract = {L-Proline was covalently tethered on thermoresponsive ionic block copolymers that formed micelles in aqueous solutions. The block copolymers consisted of a poly(N-isopropylacrylamide) (PNIPAAm) segment and an anionic or cationic polymer segment. These copolymers exhibited lower critical solution temperature (LCST) behavior at ca. 35-40°C, and achieved thermal stimuli-induced formation and dissociation of micelles. The copolymer generated micelles in aqueous solution at a higher temperature, where a catalytic aldol reaction proceeded with high diastereo- and enantioselectivities. The micelles dissociated at lower temperature to form a clear solution such that the products could be efficiently extracted from the aqueous reaction mixture. Extraction of the aldol product with an organic solvent from the aqueous solution of the anionic copolymer was more efficient than from the nonionic copolymer solution.},
keywords = {asymmetric aldol reaction, L-proline, michael addition, poly(N-isopropylacrylamide), polymer micelle, reaction in water, thermoresponsive polymer},
pubstate = {published},
tppubtype = {article}
}
L-Proline was covalently tethered on thermoresponsive ionic block copolymers that formed micelles in aqueous solutions. The block copolymers consisted of a poly(N-isopropylacrylamide) (PNIPAAm) segment and an anionic or cationic polymer segment. These copolymers exhibited lower critical solution temperature (LCST) behavior at ca. 35-40°C, and achieved thermal stimuli-induced formation and dissociation of micelles. The copolymer generated micelles in aqueous solution at a higher temperature, where a catalytic aldol reaction proceeded with high diastereo- and enantioselectivities. The micelles dissociated at lower temperature to form a clear solution such that the products could be efficiently extracted from the aqueous reaction mixture. Extraction of the aldol product with an organic solvent from the aqueous solution of the anionic copolymer was more efficient than from the nonionic copolymer solution.
2018
Jina Denise R. Galiza; Rhodora F. Nicdao; Armando M. Guidote Jr.
In: KIMIKA, vol. 29, no. 2, pp. 7-22, 2018, ISSN: 2508-0911.
Abstract | Links | Tags: chemistry background, content knowledge, professional development, self-efficacy, teaching experience
@article{Galiza2018,
title = {Educational Attainment, Teaching Experience, Professional Development and Self-Efficacy as Predictors of Chemistry Content Knowledge: Implication for the Development of a National Promotion Examination},
author = {Jina Denise R. Galiza and Rhodora F. Nicdao and Armando M. Guidote Jr.},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/258},
doi = {10.26534/kimika.v29i2.7-22},
issn = {2508-0911},
year = {2018},
date = {2018-12-04},
journal = {KIMIKA},
volume = {29},
number = {2},
pages = {7-22},
abstract = {This study examined teachers’ content knowledge (CK) in chemistry and its relationship to teachers’ chemistry background, teaching experience, involvement in professional development and self-efficacy It was further investigated which variables predicted the level of content knowledge (CK) of one hundred public secondary chemistry teachers. The data shows that the majority of science teachers have low level of CK in Chemistry. Teaching experience, professional development, chemistry background, and self-efficacy were significantly related to the CK of teachers. Teachers' professional development and self-efficacy predicted the CK of teachers.},
keywords = {chemistry background, content knowledge, professional development, self-efficacy, teaching experience},
pubstate = {published},
tppubtype = {article}
}
This study examined teachers’ content knowledge (CK) in chemistry and its relationship to teachers’ chemistry background, teaching experience, involvement in professional development and self-efficacy It was further investigated which variables predicted the level of content knowledge (CK) of one hundred public secondary chemistry teachers. The data shows that the majority of science teachers have low level of CK in Chemistry. Teaching experience, professional development, chemistry background, and self-efficacy were significantly related to the CK of teachers. Teachers' professional development and self-efficacy predicted the CK of teachers.
Mikael John A. Baltazar; Roy Kristian C. Yanela; Armando M. Guidote Jr.; Noriyuki Suzuki
Palladium-Catalyzed Carbonyl Allylation Reactions Using Tin Chloride: A Mini-Review Journal Article
In: KIMIKA, vol. 29, no. 1, pp. 22-40, 2018, ISSN: 2508-0911.
Abstract | Links | Tags: allylic alcohols, organometallic chemistry, palladium catalysis, tin chloride reduction
@article{Baltazar2018,
title = {Palladium-Catalyzed Carbonyl Allylation Reactions Using Tin Chloride: A Mini-Review},
author = {Mikael John A. Baltazar and Roy Kristian C. Yanela and Armando M. Guidote Jr. and Noriyuki Suzuki},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/254},
doi = {10.26534/kimika.v29i1.22-40},
issn = {2508-0911},
year = {2018},
date = {2018-08-04},
journal = {KIMIKA},
volume = {29},
number = {1},
pages = {22-40},
abstract = {The treatment of allylic alcohols as synthons of carbanions for carbonyl allylation reactions in the presence of a Pd-SnCl2 system has been one of the most interesting and most useful developments demonstrated by Yoshiro Masuyama and co-workers in the field of organic synthesis. The reaction makes use of palladium as an effective catalyst and tin (II) chloride as a low-valent reducing agent which also effectively transforms the allylic group to a nucleophilic group. The organic, as well as organometallic, chemistry of how the transformations occur and how the metals take part in the reaction is of great interest. These could help allow for better optimization of reagents and solvents, for better control of the extent of reaction or yield of desired product, and for possible applications in other reaction systems. This review will focus primarily on the work of Yoshiro Masuyama and various co-workers on carbonyl allylation reactions making use of a Pd-SnCl2 system or substitutes thereof.},
keywords = {allylic alcohols, organometallic chemistry, palladium catalysis, tin chloride reduction},
pubstate = {published},
tppubtype = {article}
}
The treatment of allylic alcohols as synthons of carbanions for carbonyl allylation reactions in the presence of a Pd-SnCl2 system has been one of the most interesting and most useful developments demonstrated by Yoshiro Masuyama and co-workers in the field of organic synthesis. The reaction makes use of palladium as an effective catalyst and tin (II) chloride as a low-valent reducing agent which also effectively transforms the allylic group to a nucleophilic group. The organic, as well as organometallic, chemistry of how the transformations occur and how the metals take part in the reaction is of great interest. These could help allow for better optimization of reagents and solvents, for better control of the extent of reaction or yield of desired product, and for possible applications in other reaction systems. This review will focus primarily on the work of Yoshiro Masuyama and various co-workers on carbonyl allylation reactions making use of a Pd-SnCl2 system or substitutes thereof.
2017
Yna Camille A. Mongcal; Queena N. Lee-Chua; Armando M. Guidote Jr.
Assessing In-service Teachers’ Chemistry Content Knowledge and Self-efficacy in Teaching the K to 12 Science Curriculum Journal Article
In: KIMIKA, vol. 28, no. 2, pp. 13-21, 2017, ISSN: 2508-0911.
Abstract | Links | Tags: content knowledge, educational reform, self-efficacy, teacher competence
@article{Mongcal2017,
title = {Assessing In-service Teachers’ Chemistry Content Knowledge and Self-efficacy in Teaching the K to 12 Science Curriculum},
author = {Yna Camille A. Mongcal and Queena N. Lee-Chua and Armando M. Guidote Jr.},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/236},
doi = {10.26534/kimika.v28i2.13-21},
issn = {2508-0911},
year = {2017},
date = {2017-12-19},
journal = {KIMIKA},
volume = {28},
number = {2},
pages = {13-21},
abstract = {As the K to 12 Science program was formally implemented, interventions to enhance competence and confidence of teachers in teaching science in a spiral progression approach are main concerns. This study aims to assess the chemistry content knowledge and self-efficacy of 38 in-service teachers enrolled in a graduate program from a teacher education institution using a content knowledge test (CKT) and a self-efficacy beliefs scale (SeS) using a mixed-method approach. Quantitative findings reveal that the least mastered topics in chemistry of the teacher-respondents include solutions, chemical bonding, the mole concept, gas laws, and chemical reactions. The science teachers say they are “somewhat confident” in teaching the chemistry topics. Qualitative findings include difficulties in answering the CKT and challenges encountered in teaching chemistry using the K to 12 science curriculum. In the needs analysis, key findings in the results of focus group discussion are used to verify quantitative findings. The correlation between content knowledge and self-efficacy beliefs is r = -0.12, with findings showing a negligible to low correlation. This implies that even if teachers perceive that they are “somewhat confident” in teaching chemistry topics, such beliefs do not match their content knowledge scores. Valid findings are based on the CKT results and further suggest that the CKT (not the SeS) is a good measure in determining the content learning needs of teachers.},
keywords = {content knowledge, educational reform, self-efficacy, teacher competence},
pubstate = {published},
tppubtype = {article}
}
As the K to 12 Science program was formally implemented, interventions to enhance competence and confidence of teachers in teaching science in a spiral progression approach are main concerns. This study aims to assess the chemistry content knowledge and self-efficacy of 38 in-service teachers enrolled in a graduate program from a teacher education institution using a content knowledge test (CKT) and a self-efficacy beliefs scale (SeS) using a mixed-method approach. Quantitative findings reveal that the least mastered topics in chemistry of the teacher-respondents include solutions, chemical bonding, the mole concept, gas laws, and chemical reactions. The science teachers say they are “somewhat confident” in teaching the chemistry topics. Qualitative findings include difficulties in answering the CKT and challenges encountered in teaching chemistry using the K to 12 science curriculum. In the needs analysis, key findings in the results of focus group discussion are used to verify quantitative findings. The correlation between content knowledge and self-efficacy beliefs is r = -0.12, with findings showing a negligible to low correlation. This implies that even if teachers perceive that they are “somewhat confident” in teaching chemistry topics, such beliefs do not match their content knowledge scores. Valid findings are based on the CKT results and further suggest that the CKT (not the SeS) is a good measure in determining the content learning needs of teachers.
Angelo Julian E. Perez; Armando M. Guidote Jr.; Gilbert U. Yu; Michael Ner E. Mariano
In: KIMIKA, vol. 27, no. 2, pp. 50-62, 2017, ISSN: 2508-0911.
Abstract | Links | Tags: chemistry education, general chemistry, history and philosophy of science, nature of science, philosophy of chemistry, textbook analysis
@article{Perez2017,
title = {Content Analysis of the Discussion of the Atom in General Chemistry Textbooks Using Evaluation Criteria Based on the Nature of Science and Philosophy of Chemistry},
author = {Angelo Julian E. Perez and Armando M. Guidote Jr. and Gilbert U. Yu and Michael Ner E. Mariano},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/219},
doi = {10.26534/kimika.v27i2.50-62},
issn = {2508-0911},
year = {2017},
date = {2017-02-08},
journal = {KIMIKA},
volume = {27},
number = {2},
pages = {50-62},
abstract = {Evaluation criteria are adapted from previous textbook analyses on the nature of science (NOS) in general chemistry textbooks. These criteria are used to determine how certain NOS dimensions are mentioned and elaborated in those textbooks. Such dimensions emphasize that chemistry is (1) tentative, (2) empirical, (3) model-based, (4) inferential, (5) has technological products, (6) employs instrumentation, and (7) possesses social and societal dimensions. Three book chapters were read and evaluated: the first (on chemistry in general); the second (on atomic structure); and the sixth or seventh chapters (on the electronic structure of atoms). The relevant content in each textbook were rated using the following rubric: Satisfactory and Explicit (S, 2 points); Mention and Implicit (M, 1 point); and No Mention (N, 0 point). Silberberg (2009) has the highest score among the six textbooks with 12 points out of the maximum of 14. It was rated S for five criteria, the most among the six textbooks. Despite the presence of some N evaluations, all textbooks have mentioned some or all of the NOS dimensions formulated, resulting to M and S ratings. This study concludes that NOS dimensions are already present in various ways and varying degrees in each textbook.},
keywords = {chemistry education, general chemistry, history and philosophy of science, nature of science, philosophy of chemistry, textbook analysis},
pubstate = {published},
tppubtype = {article}
}
Evaluation criteria are adapted from previous textbook analyses on the nature of science (NOS) in general chemistry textbooks. These criteria are used to determine how certain NOS dimensions are mentioned and elaborated in those textbooks. Such dimensions emphasize that chemistry is (1) tentative, (2) empirical, (3) model-based, (4) inferential, (5) has technological products, (6) employs instrumentation, and (7) possesses social and societal dimensions. Three book chapters were read and evaluated: the first (on chemistry in general); the second (on atomic structure); and the sixth or seventh chapters (on the electronic structure of atoms). The relevant content in each textbook were rated using the following rubric: Satisfactory and Explicit (S, 2 points); Mention and Implicit (M, 1 point); and No Mention (N, 0 point). Silberberg (2009) has the highest score among the six textbooks with 12 points out of the maximum of 14. It was rated S for five criteria, the most among the six textbooks. Despite the presence of some N evaluations, all textbooks have mentioned some or all of the NOS dimensions formulated, resulting to M and S ratings. This study concludes that NOS dimensions are already present in various ways and varying degrees in each textbook.
2015
Ronald G. Santos; Armando M. Guidote Jr.
The green chemistry and Filipino approach to high school experiments in Saint Paul College Pasig Journal Article
In: International Journal of Curriculum and Instruction, vol. 7, no. 2, pp. 51-57, 2015, ISSN: 1562-0506.
Abstract | Links | Tags: chemistry education in the Philippines, Filipino enculturation of chemistry, green chemistry, high school chemistry experiments, practical work
@article{Santos2015,
title = {The green chemistry and Filipino approach to high school experiments in Saint Paul College Pasig},
author = {Ronald G. Santos and Armando M. Guidote Jr.},
url = {http://ijci.wcci-international.org/index.php/IJCI/article/view/33},
issn = {1562-0506},
year = {2015},
date = {2015-11-01},
journal = {International Journal of Curriculum and Instruction},
volume = {7},
number = {2},
pages = {51-57},
abstract = {This paper is a call for teachers to initiate measures in improving the quality of high school chemistry education in the Philippines and that is by going back to practical laboratory work. The experiment presented in this paper is a proof to the possibility of tailor-made experiments that integrate principles of green chemistry. Integrating green chemistry concepts in the design of high school chemistry experiments makes students aware of the responsibility that goes with the use and production of chemicals. Moreover, the experiment was designed to consciously integrate aspects of Filipino culture, values, and traditions. Such enculturation of chemistry by giving it a Filipino flavor aims to make the students own the science and not view it as something that is highly foreign. When students can relate to the chemical concepts illuminated in their culture they become more appreciative and receptive of the science giving them meaningful and lasting learning.},
keywords = {chemistry education in the Philippines, Filipino enculturation of chemistry, green chemistry, high school chemistry experiments, practical work},
pubstate = {published},
tppubtype = {article}
}
This paper is a call for teachers to initiate measures in improving the quality of high school chemistry education in the Philippines and that is by going back to practical laboratory work. The experiment presented in this paper is a proof to the possibility of tailor-made experiments that integrate principles of green chemistry. Integrating green chemistry concepts in the design of high school chemistry experiments makes students aware of the responsibility that goes with the use and production of chemicals. Moreover, the experiment was designed to consciously integrate aspects of Filipino culture, values, and traditions. Such enculturation of chemistry by giving it a Filipino flavor aims to make the students own the science and not view it as something that is highly foreign. When students can relate to the chemical concepts illuminated in their culture they become more appreciative and receptive of the science giving them meaningful and lasting learning.
2014
Armando M. Guidote Jr.; Giselle Mae M. Pacot; Paul M. Cabacungan
Low-Cost Magnetic Stirrer from Recycled Computer Parts with Optional Hot Plate Journal Article
In: Journal of Chemical Education, vol. 99, no. 1, pp. 102-105, 2014.
Abstract | Links | Tags: first-year undergraduate/general, hands-on learning/manipulatives, high school/introductory chemistry, laboratory equipment/apparatus, laboratory instruction, public understanding/outreach
@article{Guidote2014,
title = {Low-Cost Magnetic Stirrer from Recycled Computer Parts with Optional Hot Plate},
author = {Armando M. Guidote Jr. and Giselle Mae M. Pacot and Paul M. Cabacungan},
url = {https://pubs.acs.org/doi/10.1021/ed500153r},
doi = {10.1021/ed500153r},
year = {2014},
date = {2014-10-22},
journal = {Journal of Chemical Education},
volume = {99},
number = {1},
pages = {102-105},
abstract = {Magnetic stirrers and hot plates are key components of science laboratories. However, these are not readily available in many developing countries due to their high cost. This article describes the design of a low-cost magnetic stirrer with hot plate from recycled materials. Some of the materials used are neodymium magnets and CPU fans from discarded computers and recycled electrical components from old circuit boards. This prototype was compared with a commercial magnetic stirrer with hot plate. It was noted that high temperatures were reached at similar rates, and the stirring speed was also comparable between the two. With this prototype, which costs 80% less than commercials ones, magnetic stirrers with hot plate can be readily available to enhance teaching and learning in science laboratories that need them most.},
keywords = {first-year undergraduate/general, hands-on learning/manipulatives, high school/introductory chemistry, laboratory equipment/apparatus, laboratory instruction, public understanding/outreach},
pubstate = {published},
tppubtype = {article}
}
Magnetic stirrers and hot plates are key components of science laboratories. However, these are not readily available in many developing countries due to their high cost. This article describes the design of a low-cost magnetic stirrer with hot plate from recycled materials. Some of the materials used are neodymium magnets and CPU fans from discarded computers and recycled electrical components from old circuit boards. This prototype was compared with a commercial magnetic stirrer with hot plate. It was noted that high temperatures were reached at similar rates, and the stirring speed was also comparable between the two. With this prototype, which costs 80% less than commercials ones, magnetic stirrers with hot plate can be readily available to enhance teaching and learning in science laboratories that need them most.
Armando M. Guidote Jr.; Ronald L. Reyes; Riyo Kashihara; Yasuhiko Kurusu; Yoshiro Masuyama
Electronic Effects in Oxidation Reactions Utilizing Dinuclear Copper Complexes with the Bis[3-(2-hydroxybenzylideneamino)phenyl] Sulfone Ligand Journal Article
In: KIMIKA, vol. 25, no. 2, pp. 11-22, 2014, ISSN: 2508-0911.
Abstract | Links | Tags: catalysis, copper complex, dinuclear, hydrogen peroxide, oxidation
@article{Guidote2014Electronic,
title = {Electronic Effects in Oxidation Reactions Utilizing Dinuclear Copper Complexes with the Bis[3-(2-hydroxybenzylideneamino)phenyl] Sulfone Ligand},
author = {Armando M. Guidote Jr. and Ronald L. Reyes and Riyo Kashihara and Yasuhiko Kurusu and Yoshiro Masuyama},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/180},
doi = {10.26534/kimika.v25i2.11-22},
issn = {2508-0911},
year = {2014},
date = {2014-10-20},
journal = {KIMIKA},
volume = {25},
number = {2},
pages = {11-22},
abstract = {Copper acetate and the ligands bis[3-(3-tert-butyl-2-hydroxy-5-methoxybenzylidene-amino)phenyl] sulfone and bis[3-(3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenyl] sulfone were reacted to form the complexes with 2:1 copper:ligand ratio, Cu2[B(t-Bu) (OMe)BAPS](µ-OCH3)2 (4) and with 2:2 copper:ligand ratio, Cu2[B(t-Bu)2BAPS]2 (5), respectively. Structures of 4 and 5 were determined based on IR, UV-Vis, and FAB-MS data in comparison with previously characterized related copper complexes. The two complexes 4 and 5 were utilized in the oxidation of the substrates 2,4- and 2,6-di-tert-butylphenol (dtbp) at -50C with H2O2 in CH2Cl2. The coupling products are preferred in both cases. For 2,4-dtbp, yields of 4,600% and 7,200% of 3,3’,5,5’-tetra-tert-butyl-2,2’-biphenol were achieved with the use of 4 and 5, respectively. For 2,6-dtbp, yields of 1,900% and 400% of 3,3’,5,5’-tetra-tert-butyl-4,4’-biphenol were realized utilizing 4 and 5, respectively. These show that the methoxy groups activated the complex. Based on low temperature UV-vis results, a µ-η2:η2-peroxo or a µ-hydroperoxo intermediate was possibly formed by the reaction of 4 with the H2O2. This effected the oxidation of the 2,4- and 2,6-dtbp substrates but also resulted in the attack of other complexes which acted as substrates. A proposed oxidation mechanism using complex 4 and related complexes is presented.},
keywords = {catalysis, copper complex, dinuclear, hydrogen peroxide, oxidation},
pubstate = {published},
tppubtype = {article}
}
Copper acetate and the ligands bis[3-(3-tert-butyl-2-hydroxy-5-methoxybenzylidene-amino)phenyl] sulfone and bis[3-(3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenyl] sulfone were reacted to form the complexes with 2:1 copper:ligand ratio, Cu2[B(t-Bu) (OMe)BAPS](µ-OCH3)2 (4) and with 2:2 copper:ligand ratio, Cu2[B(t-Bu)2BAPS]2 (5), respectively. Structures of 4 and 5 were determined based on IR, UV-Vis, and FAB-MS data in comparison with previously characterized related copper complexes. The two complexes 4 and 5 were utilized in the oxidation of the substrates 2,4- and 2,6-di-tert-butylphenol (dtbp) at -50C with H2O2 in CH2Cl2. The coupling products are preferred in both cases. For 2,4-dtbp, yields of 4,600% and 7,200% of 3,3’,5,5’-tetra-tert-butyl-2,2’-biphenol were achieved with the use of 4 and 5, respectively. For 2,6-dtbp, yields of 1,900% and 400% of 3,3’,5,5’-tetra-tert-butyl-4,4’-biphenol were realized utilizing 4 and 5, respectively. These show that the methoxy groups activated the complex. Based on low temperature UV-vis results, a µ-η2:η2-peroxo or a µ-hydroperoxo intermediate was possibly formed by the reaction of 4 with the H2O2. This effected the oxidation of the 2,4- and 2,6-dtbp substrates but also resulted in the attack of other complexes which acted as substrates. A proposed oxidation mechanism using complex 4 and related complexes is presented.
Henson L. Lee Yu; Perfecto N. Domingo Jr.; Elliard Roswell S. Yanza; Armando M. Guidote Jr.
Making a Low-Cost Soda Can Ethanol Burner for Out-of-Laboratory Flame Test Demonstrations and Experiments Journal Article
In: Journal of Chemistry Education, vol. 92, no. 1, pp. 127-128, 2014.
Abstract | Links | Tags: atomic properties/structure, demonstrations, hands-on learning/manipulatives, high school/introductory chemistry
@article{LeeYu2014,
title = {Making a Low-Cost Soda Can Ethanol Burner for Out-of-Laboratory Flame Test Demonstrations and Experiments},
author = {Henson L. Lee Yu and Perfecto N. Domingo Jr. and Elliard Roswell S. Yanza and Armando M. Guidote Jr.},
url = {https://pubs.acs.org/doi/10.1021/ed500411v},
doi = {10.1021/ed500411v},
year = {2014},
date = {2014-10-13},
journal = {Journal of Chemistry Education},
volume = {92},
number = {1},
pages = {127-128},
abstract = {This article demonstrates how to make a low-cost ethanol burner utilizing soda cans. It burns with a light blue flame suitable for out-of-laboratory flame test demonstrations where interference from a yellow flame needs to be avoided.},
keywords = {atomic properties/structure, demonstrations, hands-on learning/manipulatives, high school/introductory chemistry},
pubstate = {published},
tppubtype = {article}
}
This article demonstrates how to make a low-cost ethanol burner utilizing soda cans. It burns with a light blue flame suitable for out-of-laboratory flame test demonstrations where interference from a yellow flame needs to be avoided.
2013
Heide R. Rabanes; Armando M. Guidote Jr.; Joselito P. Quirino
Micellar electrokinetic chromatography of the constituents in Philippine lagundi (Vitex negundo) herbal products Journal Article
In: Microchemical Journal, vol. 112, pp. 153-158, 2013, ISSN: 0026-265X.
Abstract | Links | Tags: agnuside, chemical markers, herbal products, lagundi, MEKC, Vitex negundo
@article{Rabanes2013,
title = {Micellar electrokinetic chromatography of the constituents in Philippine lagundi (Vitex negundo) herbal products},
author = {Heide R. Rabanes and Armando M. Guidote Jr. and Joselito P. Quirino},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0026265X13001987},
doi = {10.1016/j.microc.2013.10.006},
issn = {0026-265X},
year = {2013},
date = {2013-10-08},
journal = {Microchemical Journal},
volume = {112},
pages = {153-158},
abstract = {Vitex negundo or lagundi is an important herbal medicine in Asia and various commercial products of this herb's leaves have been flooding the market. Reports on the chemical constituents of such products were limited and directed to only one selected chemical marker. Here, micellar electrokinetic chromatography using a fused silica capillary was used for analysis of the methanolic extract of Philippine lagundi herbal products. The separation solution, injection, and separation voltage was 50 mM SDS with 50 mM phosphoric acid at pH 2.5, 6 s at 25 mbar, and 20 kV at negative polarity, respectively. With UV detection at 200 nm, the LODs (S/N = 3) were in the sub-μg/mL range which were sufficient for detection without the need for on-line or off-line sample concentration. The repeatability values were all below 3.9% for migration time and peak signals. When the method was used to real samples, a flavonoid (isoorientin) and two iridoid glycosides (agnuside and negundoside) were identified as the target chemical markers within a 12 min electrophoretic run. The accuracy was from 95% to 129%. The results also suggested that agnuside was the major component in Philippine lagundi. The method was simple, effective, low cost, and can be used for authenticity evaluation of lagundi products.},
keywords = {agnuside, chemical markers, herbal products, lagundi, MEKC, Vitex negundo},
pubstate = {published},
tppubtype = {article}
}
Vitex negundo or lagundi is an important herbal medicine in Asia and various commercial products of this herb's leaves have been flooding the market. Reports on the chemical constituents of such products were limited and directed to only one selected chemical marker. Here, micellar electrokinetic chromatography using a fused silica capillary was used for analysis of the methanolic extract of Philippine lagundi herbal products. The separation solution, injection, and separation voltage was 50 mM SDS with 50 mM phosphoric acid at pH 2.5, 6 s at 25 mbar, and 20 kV at negative polarity, respectively. With UV detection at 200 nm, the LODs (S/N = 3) were in the sub-μg/mL range which were sufficient for detection without the need for on-line or off-line sample concentration. The repeatability values were all below 3.9% for migration time and peak signals. When the method was used to real samples, a flavonoid (isoorientin) and two iridoid glycosides (agnuside and negundoside) were identified as the target chemical markers within a 12 min electrophoretic run. The accuracy was from 95% to 129%. The results also suggested that agnuside was the major component in Philippine lagundi. The method was simple, effective, low cost, and can be used for authenticity evaluation of lagundi products.
2011
Heide R. Rabanes; Armando M. Guidote Jr.; Joselito P. Quirino
Capillary electrophoresis of natural products: Highlights of the last five years (2006–2010) Journal Article
In: Electrophoresis, vol. 33, no. 1, pp. 180-195, 2011.
Abstract | Links | Tags: CE, CZE/MEKC, natural products
@article{Rabanes2011,
title = {Capillary electrophoresis of natural products: Highlights of the last five years (2006–2010)},
author = {Heide R. Rabanes and Armando M. Guidote Jr. and Joselito P. Quirino},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/elps.201100223},
doi = {10.1002/elps.201100223},
year = {2011},
date = {2011-12-07},
journal = {Electrophoresis},
volume = {33},
number = {1},
pages = {180-195},
abstract = {An extensive search of the published research and review articles indicated a growing number of works that employed electroseparation techniques. Capillary zone electrophoresis (CZE) and electrokinetic chromatography (EKC), in particular, were found to be popular for the analyses of natural products. This review outlines the important developments in this field over the years, especially during the 2006–2010 period. An overview of the natural product applications such as pharmaceuticals/herbal products, fingerprinting and quality control, food and food contaminants, and toxicological compounds of interest to forensics were presented. Important areas of detection strategies, microchips, sample preconcentration, and chiral separations were also discussed. Hence, quick information was provided on the researches already undertaken and the possibilities of unexplored areas. In addition, fundamental concepts for the understanding of CZE and EKC and their suitability for natural products analyses were briefly discussed.},
keywords = {CE, CZE/MEKC, natural products},
pubstate = {published},
tppubtype = {article}
}
An extensive search of the published research and review articles indicated a growing number of works that employed electroseparation techniques. Capillary zone electrophoresis (CZE) and electrokinetic chromatography (EKC), in particular, were found to be popular for the analyses of natural products. This review outlines the important developments in this field over the years, especially during the 2006–2010 period. An overview of the natural product applications such as pharmaceuticals/herbal products, fingerprinting and quality control, food and food contaminants, and toxicological compounds of interest to forensics were presented. Important areas of detection strategies, microchips, sample preconcentration, and chiral separations were also discussed. Hence, quick information was provided on the researches already undertaken and the possibilities of unexplored areas. In addition, fundamental concepts for the understanding of CZE and EKC and their suitability for natural products analyses were briefly discussed.
Ma. Henrietta Olmos-Dela Cruz; Rene Angelo S. Macahig; Mailyn M. Terrado; Henson L. Lee Yu; Armando M. Guidote Jr.; Joselito P. Quirino
Biomarkers of Asthma: Recent Patents from 2009-2011 Journal Article
In: Recent Patents on Biomarkers, vol. 2, no. 1, pp. 54-59, 2011, ISSN: 2210-3104.
Abstract | Links | Tags: asthma, biomarkers, bronchoalveolar lavage proteins, diagnosis, exhaled biomarkers, mast cell stability, metabolites, proteins, serum inflammatory biomarkers, small molecules
@article{DelaCruz2011,
title = {Biomarkers of Asthma: Recent Patents from 2009-2011},
author = {Ma. Henrietta Olmos-Dela Cruz and Rene Angelo S. Macahig and Mailyn M. Terrado and Henson L. Lee Yu and Armando M. Guidote Jr. and Joselito P. Quirino},
url = {https://www.eurekaselect.com/94950/article},
doi = {10.2174/2210309011202010054},
issn = {2210-3104},
year = {2011},
date = {2011-09-26},
journal = {Recent Patents on Biomarkers},
volume = {2},
number = {1},
pages = {54-59},
abstract = {This review informs on current literature on patents for biomarkers for asthma from 2009 to 2011. Variable airflow obstruction in asthma is generally triggered by gene-environment interactions that can lead to key symptoms of cough, shortness of breath, chest tightness, and wheezing. The episodic and variable degrees of airway hyperresponsiveness arise from a variety of inflammatory pathways that can make diagnosis and management difficult. Standard pulmonary function tests used for the diagnosis of asthma may fail to predict individual responses to the standard bronchodilator and corticosteroid therapies. Phenotypic predispositions can alter the severity of the asthmatic condition and treatment response. Biomarkers from sputum, exhaled gases, exhaled breath condensates, urine, serum, and broncheolaveolar fluid lavage proteins are currently explored to provide objective metrics for identifying individuals at risk, provide therapy guidance, monitor disease progression and evaluate response to therapy, as a supplement to standard pulmonary function tests. Updates on the refinement of technologies, inherent limitations and benefits of these biomarkers are discussed to provide insights on how current understanding of pathologic mechanisms has been applied to provide information for addressing gaps in the diagnosis and management of asthma.},
keywords = {asthma, biomarkers, bronchoalveolar lavage proteins, diagnosis, exhaled biomarkers, mast cell stability, metabolites, proteins, serum inflammatory biomarkers, small molecules},
pubstate = {published},
tppubtype = {article}
}
This review informs on current literature on patents for biomarkers for asthma from 2009 to 2011. Variable airflow obstruction in asthma is generally triggered by gene-environment interactions that can lead to key symptoms of cough, shortness of breath, chest tightness, and wheezing. The episodic and variable degrees of airway hyperresponsiveness arise from a variety of inflammatory pathways that can make diagnosis and management difficult. Standard pulmonary function tests used for the diagnosis of asthma may fail to predict individual responses to the standard bronchodilator and corticosteroid therapies. Phenotypic predispositions can alter the severity of the asthmatic condition and treatment response. Biomarkers from sputum, exhaled gases, exhaled breath condensates, urine, serum, and broncheolaveolar fluid lavage proteins are currently explored to provide objective metrics for identifying individuals at risk, provide therapy guidance, monitor disease progression and evaluate response to therapy, as a supplement to standard pulmonary function tests. Updates on the refinement of technologies, inherent limitations and benefits of these biomarkers are discussed to provide insights on how current understanding of pathologic mechanisms has been applied to provide information for addressing gaps in the diagnosis and management of asthma.
Agnes T. Aranas; Armando M. Guidote Jr.; Paul R. Haddad; Joselito P. Quirino
Sweeping–micellar electrokinetic chromatography for the simultaneous analysis of tricyclic antidepressant and β-blocker drugs in wastewater Journal Article
In: Talanta, vol. 85, no. 1, pp. 86-90, 2011, ISSN: 0039-9140.
Abstract | Links | Tags: micellar electrokinetic chromatography, on-line sample preconcentration, sweeping, tricyclic antidepressant drugs, β-blocker drugs
@article{Aranas2011,
title = {Sweeping–micellar electrokinetic chromatography for the simultaneous analysis of tricyclic antidepressant and β-blocker drugs in wastewater},
author = {Agnes T. Aranas and Armando M. Guidote Jr. and Paul R. Haddad and Joselito P. Quirino},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0039914011002372},
doi = {10.1016/j.talanta.2011.03.032},
issn = {0039-9140},
year = {2011},
date = {2011-03-15},
journal = {Talanta},
volume = {85},
number = {1},
pages = {86-90},
abstract = {The simultaneous analysis of tricyclic antidepressant (amitriptyline, clomipramine, doxepin and nortriptyline) and β-blocker (alprenolol, labetalol and propranolol) drugs in wastewater was developed via sweeping–micellar electrokinetic chromatography (MEKC) together with a simple liquid–liquid extraction step. For sweeping–MEKC, the amount of organic modifier in the separation electrolyte, the concentration of phosphoric acid in the sample matrix and the injection time of the sample were optimized. Sensitivity enhancements of up to 305-fold were achieved via sweeping. This allowed limits of detection (LOD) from 7 to 27 ng/mL. The relative standard deviations of migration time, corrected peak area and peak height were less than 3.2%, 7.8% and 4.5%, respectively. Liquid–liquid extraction using dichloromethane as solvent afforded up to 21-fold enrichment of the drugs from spiked wastewater. No interference of the sample matrix was observed and recoveries were obtained in the range of 77–113% for all analytes except labetalol at three spiking levels of 16, 80 and 160 ng/mL. Detection at the ng/mL level makes this simple, environmentally friendly and cost effective method competitive against recently reported methods using advanced liquid-phase separation techniques for monitoring similar drugs in wastewater.},
keywords = {micellar electrokinetic chromatography, on-line sample preconcentration, sweeping, tricyclic antidepressant drugs, β-blocker drugs},
pubstate = {published},
tppubtype = {article}
}
The simultaneous analysis of tricyclic antidepressant (amitriptyline, clomipramine, doxepin and nortriptyline) and β-blocker (alprenolol, labetalol and propranolol) drugs in wastewater was developed via sweeping–micellar electrokinetic chromatography (MEKC) together with a simple liquid–liquid extraction step. For sweeping–MEKC, the amount of organic modifier in the separation electrolyte, the concentration of phosphoric acid in the sample matrix and the injection time of the sample were optimized. Sensitivity enhancements of up to 305-fold were achieved via sweeping. This allowed limits of detection (LOD) from 7 to 27 ng/mL. The relative standard deviations of migration time, corrected peak area and peak height were less than 3.2%, 7.8% and 4.5%, respectively. Liquid–liquid extraction using dichloromethane as solvent afforded up to 21-fold enrichment of the drugs from spiked wastewater. No interference of the sample matrix was observed and recoveries were obtained in the range of 77–113% for all analytes except labetalol at three spiking levels of 16, 80 and 160 ng/mL. Detection at the ng/mL level makes this simple, environmentally friendly and cost effective method competitive against recently reported methods using advanced liquid-phase separation techniques for monitoring similar drugs in wastewater.
2010
Joselito P. Quirino; Armando M. Guidote Jr.
Two-step stacking in capillary zone electrophoresis featuring sweeping and micelle to solvent stacking: II. Organic anions Journal Article
In: Journal of Chromatography A, vol. 1218, no. 7, pp. 1004-1010, 2010, ISSN: 0021-9673.
Abstract | Links | Tags: capillary zone electrophoresis, herbicides, hypolipidaemic drugs, micelle to solvent stacking, non-steroidal anti-inflammatory drugs, on-line sample concentration, sweeping
@article{Quirino2010,
title = {Two-step stacking in capillary zone electrophoresis featuring sweeping and micelle to solvent stacking: II. Organic anions},
author = {Joselito P. Quirino and Armando M. Guidote Jr.},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0021967310018182},
doi = {10.1016/j.chroma.2010.12.095},
issn = {0021-9673},
year = {2010},
date = {2010-12-21},
journal = {Journal of Chromatography A},
volume = {1218},
number = {7},
pages = {1004-1010},
abstract = {Two-step stacking of organic anions by sweeping and micelle to solvent stacking (MSS) using cationic cetyltrimethylammonium micelles in co-electroosmotic flow (co-EOF) capillary zone electrophoresis (CZE) is described. The co-EOF condition where the direction of the EOF is the same as the test anions was satisfied by positive dynamic coating of a fused silica capillary with hexadimethrine bromide. The strategy was as follows. After conditioning the capillary with the background solution (BGS), a micellar solution (MS) was injected before the sample solution (S). The BGS, MS and S have similar conductivities. Voltage was applied at negative polarity. The analytes in the micelle-free S zone were swept by micelles from the MS. The swept analytes were brought by the micelles to the MSS boundary where the second stacking step was induced by the presence of organic solvent in the BGS. Finally was the separation of concentrated analytes by CZE. The effect of electrolyte concentration in the S, injection time of the MS and the S and surfactant concentration in the MS were studied. A 20–29, 17–33 and 18–21 times increase in peak height sensitivity was obtained for the test hypolipidaemic drugs (gemfibrozil, fluvastatin and atorvastatin), non-steroidal anti-inflammatory drugs (diflunisal, naproxen, ketoprofen, indoprofen and indomethacin), and herbicides (mecoprop and fenoprop), respectively. The LODs (S/N = 3) were from 0.05 to 0.55 μg/mL. The intraday and interday repeatabilities (%RSD, n = 12) in terms of retention time, corrected peak area, and peak heights was less than 3.6, 8.9, and 10.8%, respectively. The application of sweeping and MSS in co-EOF CZE together with a simple extraction procedure to a waste water sample spiked with the test herbicides was also demonstrated.},
keywords = {capillary zone electrophoresis, herbicides, hypolipidaemic drugs, micelle to solvent stacking, non-steroidal anti-inflammatory drugs, on-line sample concentration, sweeping},
pubstate = {published},
tppubtype = {article}
}
Two-step stacking of organic anions by sweeping and micelle to solvent stacking (MSS) using cationic cetyltrimethylammonium micelles in co-electroosmotic flow (co-EOF) capillary zone electrophoresis (CZE) is described. The co-EOF condition where the direction of the EOF is the same as the test anions was satisfied by positive dynamic coating of a fused silica capillary with hexadimethrine bromide. The strategy was as follows. After conditioning the capillary with the background solution (BGS), a micellar solution (MS) was injected before the sample solution (S). The BGS, MS and S have similar conductivities. Voltage was applied at negative polarity. The analytes in the micelle-free S zone were swept by micelles from the MS. The swept analytes were brought by the micelles to the MSS boundary where the second stacking step was induced by the presence of organic solvent in the BGS. Finally was the separation of concentrated analytes by CZE. The effect of electrolyte concentration in the S, injection time of the MS and the S and surfactant concentration in the MS were studied. A 20–29, 17–33 and 18–21 times increase in peak height sensitivity was obtained for the test hypolipidaemic drugs (gemfibrozil, fluvastatin and atorvastatin), non-steroidal anti-inflammatory drugs (diflunisal, naproxen, ketoprofen, indoprofen and indomethacin), and herbicides (mecoprop and fenoprop), respectively. The LODs (S/N = 3) were from 0.05 to 0.55 μg/mL. The intraday and interday repeatabilities (%RSD, n = 12) in terms of retention time, corrected peak area, and peak heights was less than 3.6, 8.9, and 10.8%, respectively. The application of sweeping and MSS in co-EOF CZE together with a simple extraction procedure to a waste water sample spiked with the test herbicides was also demonstrated.
Armando M. Guidote Jr.; Joselito P. Quirino
On-line sample concentration of organic anions in capillary zone electrophoresis by micelle to solvent stacking Journal Article
In: Journal of Chromatography A, vol. 1217, no. 40, pp. 6290-6295, 2010, ISSN: 0021-9673.
Abstract | Links | Tags: capillary zone electrophoresis, hypolipidaemic drugs, micelle to solvent stacking, on-line sample concentration
@article{Guidote2010,
title = {On-line sample concentration of organic anions in capillary zone electrophoresis by micelle to solvent stacking},
author = {Armando M. Guidote Jr. and Joselito P. Quirino},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0021967310010496},
doi = {10.1016/j.chroma.2010.07.077},
issn = {0021-9673},
year = {2010},
date = {2010-07-27},
journal = {Journal of Chromatography A},
volume = {1217},
number = {40},
pages = {6290-6295},
abstract = {Micelle to solvent stacking (MSS) is a new on-line sample concentration technique for charged analytes in capillary zone electrophoresis (CZE). Sample concentration in MSS mainly relies on the reversal in the effective electrophoretic mobility of the analyte at the boundary zone between the sample solution (S) and CZE background solution (BGS) inside the capillary. The basic condition for MSS is that the S is prepared in a matrix that contains an additive (i.e., micelles) which interacts with and has an opposite charge compared to the analytes. In addition, the BGS must contain a sufficient percentage of organic solvent. MSS was first reported for organic cations using anionic dodecyl sulfate micelles as additive in the S and methanol or acetonitrile as organic solvent in the BGS. Here, theoretical and experimental studies on MSS are described for organic anions using cationic cetyltrimethyl ammonium micelles as additive in the S and methanol as organic solvent in the BGS. Up to an order of magnitude improvement in concentration sensitivity was obtained for the test hypolipidaemic drugs using MSS in CZE with UV detection. The optimized method was also evaluated to the analysis of a spiked wastewater sample that was subjected to a simple extraction step.},
keywords = {capillary zone electrophoresis, hypolipidaemic drugs, micelle to solvent stacking, on-line sample concentration},
pubstate = {published},
tppubtype = {article}
}
Micelle to solvent stacking (MSS) is a new on-line sample concentration technique for charged analytes in capillary zone electrophoresis (CZE). Sample concentration in MSS mainly relies on the reversal in the effective electrophoretic mobility of the analyte at the boundary zone between the sample solution (S) and CZE background solution (BGS) inside the capillary. The basic condition for MSS is that the S is prepared in a matrix that contains an additive (i.e., micelles) which interacts with and has an opposite charge compared to the analytes. In addition, the BGS must contain a sufficient percentage of organic solvent. MSS was first reported for organic cations using anionic dodecyl sulfate micelles as additive in the S and methanol or acetonitrile as organic solvent in the BGS. Here, theoretical and experimental studies on MSS are described for organic anions using cationic cetyltrimethyl ammonium micelles as additive in the S and methanol as organic solvent in the BGS. Up to an order of magnitude improvement in concentration sensitivity was obtained for the test hypolipidaemic drugs using MSS in CZE with UV detection. The optimized method was also evaluated to the analysis of a spiked wastewater sample that was subjected to a simple extraction step.
Armando M. Guidote Jr.; Maricar O. Ribo-Ramos; Dante Gilbert L. De Leon
Extraction Experiments Using Commercially Available Spices Journal Article
In: KIMIKA, vol. 23, no. 1, pp. 32-37, 2010, ISSN: 2508-0911.
Abstract | Links | Tags: annatto, high school, separation, solubility, Spanish paprika, turmeric
@article{Guidote2010b,
title = {Extraction Experiments Using Commercially Available Spices},
author = {Armando M. Guidote Jr. and Maricar O. Ribo-Ramos and Dante Gilbert L. De Leon},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/10},
doi = {10.26534/kimika.v23i1.32-37},
issn = {2508-0911},
year = {2010},
date = {2010-03-01},
journal = {KIMIKA},
volume = {23},
number = {1},
pages = {32-37},
abstract = {Safe and cost-effective experiments were designed for high school students to enhance their laboratory skills and knowledge on polarity and separation of mixtures. Annatto, Spanish paprika and turmeric were extracted yielding red-orange, light red-orange and yellow color, respectively. These were combined with a blue aqueous solution made from food color resulting to green mixtures. These were all extracted with kerosene or oil/kerosene. The non-polar solutes for each mixtures combined with the kerosene or oil/kerosene layer, making the polar phase blue again. Students gained a better understanding of the concepts as shown in their laboratory report and test results.},
keywords = {annatto, high school, separation, solubility, Spanish paprika, turmeric},
pubstate = {published},
tppubtype = {article}
}
Safe and cost-effective experiments were designed for high school students to enhance their laboratory skills and knowledge on polarity and separation of mixtures. Annatto, Spanish paprika and turmeric were extracted yielding red-orange, light red-orange and yellow color, respectively. These were combined with a blue aqueous solution made from food color resulting to green mixtures. These were all extracted with kerosene or oil/kerosene. The non-polar solutes for each mixtures combined with the kerosene or oil/kerosene layer, making the polar phase blue again. Students gained a better understanding of the concepts as shown in their laboratory report and test results.
2009
Agnes T. Aranas; Armando M. Guidote Jr.; Joselito P. Quirino
Sweeping and new on-line sample preconcentration techniques in capillary electrophoresis Journal Article
In: Analytical and Bioanalytical Chemistry, vol. 394, pp. 175-185, 2009.
Abstract | Links | Tags: analyte focusing by micelle collapse, capillary electrophoresis, on-line sample preconcentration, sample stacking, sweeping
@article{Aranas2009,
title = {Sweeping and new on-line sample preconcentration techniques in capillary electrophoresis},
author = {Agnes T. Aranas and Armando M. Guidote Jr. and Joselito P. Quirino},
url = {https://link.springer.com/article/10.1007/s00216-009-2646-7},
doi = {10.1007/s00216-009-2646-7},
year = {2009},
date = {2009-03-03},
journal = {Analytical and Bioanalytical Chemistry},
volume = {394},
pages = {175-185},
abstract = {Sweeping is a powerful on-line sample preconcentration technique that improves the concentration sensitivity of capillary electrophoresis (CE). This approach is designed to focus the analyte into narrow bands within the capillary, thereby increasing the sample volume that can be injected, without any loss of CE efficiency. It utilizes the interactions between an additive [i.e., a pseudostationary phase (PS) or complexing agent] in the separation buffer and the sample in a matrix that is devoid of the additive used. The accumulation occurs due to chromatographic partitioning, complexation or any interaction between analytes and the additive through electrophoresis. The extent of the preconcentration is dependent on the strength of interaction involved. Both charged and neutral analytes can be preconcentrated. Remarkable improvements—up to several thousandfold—in detection sensitivity have been achieved. This suggests that sweeping is a superior and general approach to on-line sample preconcentration in CE. The focusing mechanism of sweeping under different experimental conditions and its combination with other on-line preconcentration techniques are discussed in this review. The recently introduced techniques of transient trapping (tr-trapping) and analyte focusing by micelle collapse (AFMC) as well as other novel approaches to on-line sample preconcentration are also described.},
keywords = {analyte focusing by micelle collapse, capillary electrophoresis, on-line sample preconcentration, sample stacking, sweeping},
pubstate = {published},
tppubtype = {article}
}
Sweeping is a powerful on-line sample preconcentration technique that improves the concentration sensitivity of capillary electrophoresis (CE). This approach is designed to focus the analyte into narrow bands within the capillary, thereby increasing the sample volume that can be injected, without any loss of CE efficiency. It utilizes the interactions between an additive [i.e., a pseudostationary phase (PS) or complexing agent] in the separation buffer and the sample in a matrix that is devoid of the additive used. The accumulation occurs due to chromatographic partitioning, complexation or any interaction between analytes and the additive through electrophoresis. The extent of the preconcentration is dependent on the strength of interaction involved. Both charged and neutral analytes can be preconcentrated. Remarkable improvements—up to several thousandfold—in detection sensitivity have been achieved. This suggests that sweeping is a superior and general approach to on-line sample preconcentration in CE. The focusing mechanism of sweeping under different experimental conditions and its combination with other on-line preconcentration techniques are discussed in this review. The recently introduced techniques of transient trapping (tr-trapping) and analyte focusing by micelle collapse (AFMC) as well as other novel approaches to on-line sample preconcentration are also described.
2004
Armando M. Guidote Jr.; Tomoko Imajo; Yoshiro Masuyama
In: KIMIKA, vol. 20, pp. 17-20, 2004.
Abstract | Links | Tags: cobalt, complex, dinuclear, synthesis
@article{Guidote2004,
title = {Possible cobalt-cobalt bridging by a hemiacetal in the dinuclear cobalt complex bearing the ligand bis(3-(2-Pyridylmethyleneamino)phenyl) sulfone},
author = {Armando M. Guidote Jr. and Tomoko Imajo and Yoshiro Masuyama},
url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/142},
doi = {10.26534/kimika.v20i1.17-20},
year = {2004},
date = {2004-01-01},
journal = {KIMIKA},
volume = {20},
pages = {17-20},
abstract = {A dinuclear cobalt complex bearing the ligand bis(3-(2-pyridylmethyleneamino)phenyl) sulfone (BPMAPS) was prepared. It is proposed that the structure of this is [Co2(BPMAPS)(m-OAcM)2(hemi-Et)]PF6 wherein the cobalt centers are bridged by two carboxylato groups in m-fashion and a hemiacetal with an ethoxy group (hemi-Et). This proposal is based on the similarity of the FT-IR, UV-Vis, and FAB-MS results with the crystallographically characterized dinuclear manganese complex [Mn2(BPMAPS)(m-OAc)2(hemi-Me)]PF6, and elemental analysis results.},
keywords = {cobalt, complex, dinuclear, synthesis},
pubstate = {published},
tppubtype = {article}
}
A dinuclear cobalt complex bearing the ligand bis(3-(2-pyridylmethyleneamino)phenyl) sulfone (BPMAPS) was prepared. It is proposed that the structure of this is [Co2(BPMAPS)(m-OAcM)2(hemi-Et)]PF6 wherein the cobalt centers are bridged by two carboxylato groups in m-fashion and a hemiacetal with an ethoxy group (hemi-Et). This proposal is based on the similarity of the FT-IR, UV-Vis, and FAB-MS results with the crystallographically characterized dinuclear manganese complex [Mn2(BPMAPS)(m-OAc)2(hemi-Me)]PF6, and elemental analysis results.
2003
Dante Gilbert L. De Leon; Armando M. Guidote Jr.; Fred Juergens; Ed Vitz
Solvent Extraction Using Safe and Commonly Available Materials To Demonstrate the Difference in Solubility of Two Mixed Solutes Journal Article
In: Journal of Chemistry Education, vol. 80, no. 4, pp. 436, 2003.
Abstract | Links | Tags: demonstrations, high school/introductory chemistry, solutions/solvents, tested demonstrations
@article{DeLeon2003,
title = {Solvent Extraction Using Safe and Commonly Available Materials To Demonstrate the Difference in Solubility of Two Mixed Solutes},
author = {Dante Gilbert L. De Leon and Armando M. Guidote Jr. and Fred Juergens and Ed Vitz},
url = {https://pubs.acs.org/doi/abs/10.1021/ed080p436},
doi = {10.1021/ed080p436},
year = {2003},
date = {2003-04-01},
journal = {Journal of Chemistry Education},
volume = {80},
number = {4},
pages = {436},
abstract = {A blue, aqueous solution of copper(II) sulfate is mixed with a red ethanolic solution of sudan III forming a purple solution. This mixture is extracted with a nonpolar solvent, resulting in the separation of the red and blue compounds. The nonpolar solvent may be kerosene, vegetable oil, mineral oil, or hexanes. Notes on handling are included.},
keywords = {demonstrations, high school/introductory chemistry, solutions/solvents, tested demonstrations},
pubstate = {published},
tppubtype = {article}
}
A blue, aqueous solution of copper(II) sulfate is mixed with a red ethanolic solution of sudan III forming a purple solution. This mixture is extracted with a nonpolar solvent, resulting in the separation of the red and blue compounds. The nonpolar solvent may be kerosene, vegetable oil, mineral oil, or hexanes. Notes on handling are included.
2001
Armando M. Guidote Jr.; Ken-ichi Ando; Kazunori Terada; Yasuhiko Kurusu; Hirotaka Nagao; Yoshiro Masuyama
In: Inorganica Chimica Acta, vol. 324, pp. 203-211, 2001.
Abstract | Links | Tags: catalysis, copper complex, dinuclear, oxidation, schiff base type ligand
@article{Guidote2001,
title = {Synthesis, characterization and reactivity of a series of dinuclear copper complexes bearing the ligand bis[3-(2-hydroxybenzylideneamino)phenyl] sulfone and derivatives},
author = {Armando M. Guidote Jr. and Ken-ichi Ando and Kazunori Terada and Yasuhiko Kurusu and Hirotaka Nagao and Yoshiro Masuyama},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0020169301005898},
doi = {10.1016/S0020-1693(01)00589-8},
year = {2001},
date = {2001-11-15},
journal = {Inorganica Chimica Acta},
volume = {324},
pages = {203-211},
abstract = {The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS] (μ-OH)2 (2), and Cu2[BCl2BAPS] (μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2. The results show that (1) the coupling products are preferred when CH2Cl2 is used; and (2) the quinone yield increases when THF is utilized. In CH2Cl2 with 2,4-dtbp, the yield of the coupling product based on the complex amount, is in the order 2, 1, and 3 with yields of 6300, 4700 and 200%, respectively. Low temperature UV–Vis results of the reaction of 1 with H2O2 showed the growth of peaks at 390 and 580 nm indicative of a μ-η2:η2-peroxo or μ-η1:η1-hydroperoxo intermediate. At −50 °C, this spectrum does not change. But when warmed to 0 °C, a spectrum similar to the original spectrum was obtained. This probably indicates hydrogen radical abstractions of the peroxo intermediate from solvents, and if excess H2O2 is present, the peroxo intermediate may again be formed. This reusability of the complex explains the high yield using 1 and 2.
The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS](μ-OH)2 (2), and Cu2[BCl2BAPS](μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2.},
keywords = {catalysis, copper complex, dinuclear, oxidation, schiff base type ligand},
pubstate = {published},
tppubtype = {article}
}
The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS] (μ-OH)2 (2), and Cu2[BCl2BAPS] (μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2. The results show that (1) the coupling products are preferred when CH2Cl2 is used; and (2) the quinone yield increases when THF is utilized. In CH2Cl2 with 2,4-dtbp, the yield of the coupling product based on the complex amount, is in the order 2, 1, and 3 with yields of 6300, 4700 and 200%, respectively. Low temperature UV–Vis results of the reaction of 1 with H2O2 showed the growth of peaks at 390 and 580 nm indicative of a μ-η2:η2-peroxo or μ-η1:η1-hydroperoxo intermediate. At −50 °C, this spectrum does not change. But when warmed to 0 °C, a spectrum similar to the original spectrum was obtained. This probably indicates hydrogen radical abstractions of the peroxo intermediate from solvents, and if excess H2O2 is present, the peroxo intermediate may again be formed. This reusability of the complex explains the high yield using 1 and 2.
The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS](μ-OH)2 (2), and Cu2[BCl2BAPS](μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2.
The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS](μ-OH)2 (2), and Cu2[BCl2BAPS](μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2.
Armando M. Guidote Jr.; Ken-ichi Ando; Yasuhiko Kurusu; Hirotaka Nagao; Yoshiro Masuyama
In: Inorganica Chimica Acta, vol. 314, pp. 27-36, 2001.
Abstract | Links | Tags: cobalt complex, dinuclear, manganese complex, schiff base type ligand
@article{Guidote2001b,
title = {Syntheses and characterization of homodinuclear manganese and cobalt complexes bridged by a hemiacetal or by an acetato group in a μ-(η2:η1) bridging mode},
author = {Armando M. Guidote Jr. and Ken-ichi Ando and Yasuhiko Kurusu and Hirotaka Nagao and Yoshiro Masuyama},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0020169301002948},
doi = {10.1016/S0020-1693(01)00294-8},
year = {2001},
date = {2001-03-07},
journal = {Inorganica Chimica Acta},
volume = {314},
pages = {27-36},
abstract = {The complex [Mn2(BPMAPS)(μ-OAc)2(hemi)]PF6 (1), where hemi is the hemiacetal group, methoxy(2-pyridyl)methoxo, was prepared from bis[3-(2-pyridylmethyleneamino)phenyl] sulfone (BPMAPS), 2-pyridinecarbaldehyde, and manganese(II) acetate in methanol. The complexes Mn2(BPMAPS)(μ-OAc)2(μ-1,1-OAc)(η1-OAc) (2) and Co2(BPMAPS)(μ-OAc)2-[μ-(η2:η1)OAc](η1-OAc) (3) were prepared from manganese(II) acetate and cobalt(II) acetate, respectively, with BPMAPS in methanol. All three complexes were characterized by elemental analysis, FT-IR, MS, UV–Vis spectroscopy, and X-ray crystallography. The manganese ions of complex 1 are bridged by a hemiacetal through the oxygen atom of the alkoxo with the nitrogen atom of the pyridine group coordinating to one of the manganese atoms. The metal ions of complexes 2 and 3 are bridged by acetato groups in μ-1,1 or μ-η2:η1 modes, respectively.},
keywords = {cobalt complex, dinuclear, manganese complex, schiff base type ligand},
pubstate = {published},
tppubtype = {article}
}
The complex [Mn2(BPMAPS)(μ-OAc)2(hemi)]PF6 (1), where hemi is the hemiacetal group, methoxy(2-pyridyl)methoxo, was prepared from bis[3-(2-pyridylmethyleneamino)phenyl] sulfone (BPMAPS), 2-pyridinecarbaldehyde, and manganese(II) acetate in methanol. The complexes Mn2(BPMAPS)(μ-OAc)2(μ-1,1-OAc)(η1-OAc) (2) and Co2(BPMAPS)(μ-OAc)2-[μ-(η2:η1)OAc](η1-OAc) (3) were prepared from manganese(II) acetate and cobalt(II) acetate, respectively, with BPMAPS in methanol. All three complexes were characterized by elemental analysis, FT-IR, MS, UV–Vis spectroscopy, and X-ray crystallography. The manganese ions of complex 1 are bridged by a hemiacetal through the oxygen atom of the alkoxo with the nitrogen atom of the pyridine group coordinating to one of the manganese atoms. The metal ions of complexes 2 and 3 are bridged by acetato groups in μ-1,1 or μ-η2:η1 modes, respectively.
1994
Fabian M. Dayrit; Armando M. Guidote Jr.; Maximino L. Generalao; Constante Serna
Determination of the Quinine Content in the Bark of the Cinchona Tree Grown in Mt. Kitanglad, Bukidnon Journal Article
In: Philippine Journal of Science, vol. 123, no. 3, pp. 215-227, 1994.
@article{Dayrit1994,
title = {Determination of the Quinine Content in the Bark of the Cinchona Tree Grown in Mt. Kitanglad, Bukidnon},
author = {Fabian M. Dayrit and Armando M. Guidote Jr. and Maximino L. Generalao and Constante Serna},
url = {https://philjournalsci.dost.gov.ph/publication/regular-issues/past-issues},
year = {1994},
date = {1994-07-01},
journal = {Philippine Journal of Science},
volume = {123},
number = {3},
pages = {215-227},
abstract = {A rapid, accurate, and inexpensive quantitative HPTLC/densitometry procedure was developed for the simultaneous determination of the four major alkaloids found in the bark of Cinchona species: quinine, quinidine, cinchonine, and cinchonidine. Linearity and % recovery of the procedure were good. This procedure was applied to the analysis of bark samples from seven Cinchona species found in the DENR Cinchona Reforestation Project located in Mt. Kitanglad, Bukidnon: C. calisaya, C. hybrida, C. kartamanah, C. ledgeriana, C. officinalis, C. succirubra, and C. tjinjiroena. The species with the highest % quinine yield were C. ledgeriana, C. officinalis, and C. tjinjiroena.},
keywords = {-},
pubstate = {published},
tppubtype = {article}
}
A rapid, accurate, and inexpensive quantitative HPTLC/densitometry procedure was developed for the simultaneous determination of the four major alkaloids found in the bark of Cinchona species: quinine, quinidine, cinchonine, and cinchonidine. Linearity and % recovery of the procedure were good. This procedure was applied to the analysis of bark samples from seven Cinchona species found in the DENR Cinchona Reforestation Project located in Mt. Kitanglad, Bukidnon: C. calisaya, C. hybrida, C. kartamanah, C. ledgeriana, C. officinalis, C. succirubra, and C. tjinjiroena. The species with the highest % quinine yield were C. ledgeriana, C. officinalis, and C. tjinjiroena.