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Oguri S, Nomura M, Fujita Y. A new strategy for the selective determination of d-amino acids: Enzymatic and chemical modifications for pre-column derivatization. J Chromatogr A 2005; 1078:51-8. [PMID: 16007981 DOI: 10.1016/j.chroma.2005.04.084] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new strategy for the selective determination of D-amino acids (DAAs) employing a pre-column derivatization was designed with concepts based on both enzymatic and chemical modifications. Selective determination of DAAs was accomplished by following: DAA was enzymatically modified with D-amino acid oxidase (DAAO: EC 1.4.3.3) to form an alpha-keto acid. Subsequently, resulting alpha-keto acid was detected by high-performance liquid chromatography (HPLC) after chemical modification with o-phenylenediamine (PDA) in the presence of 2-mercaptoethanol (2ME) to give the corresponding quinoxalinol derivative (PDA-alpha-keto acid derivative). After optimizing the pre-column derivatization and HPLC separation, five peaks corresponding to DAAs (D-alanine, D-leucine, D-methionine, D-phenylalanine, D-valine (as the standard mixture of DAAs in this paper) were separately eluted and monitored by means of a conventional HPLC system with a gradient elution on octadecyl silica gel (ODS) column and a fluorescence detector (Ex.: 341 nm, Em.: 413 nm), respectively. It was confirmed that the present method was incapable of detecting L-amino acids (LAA) when a sample solution consisting of both LAAs and DAAs was examined. The linearity of the peak-area responses to their concentration range of DAAs from 10 to 500 microM is 0.994-1.000, and their detection limits were 0.2-1 microM (signal/noise = 3). When this method was applied to a methanolic extract of short-necked clams, Ruditapes philippinarum (in Japanese, Asari), a big peak, corresponding to D-alanine was detected, corresponding to 2.9 mg/g D-alanine. In this paper, we present an example of pre-column derivatization method that was newly configured to take into account both the biological and chemical properties of the substances in question.
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Affiliation(s)
- Shigeyuki Oguri
- Laboratory of Food Hygiene, Department of Home Economics, Aichi-Gakusen University, 28 Kamikawanari, Hegoshi-cho, Okazaki-city 444-8520, Japan.
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Li W, Cohen LH. Quantitation of endogenous analytes in biofluid without a true blank matrix. Anal Chem 2004; 75:5854-9. [PMID: 14588026 DOI: 10.1021/ac034505u] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A method is presented that describes a reliable and practical procedure for quantitation of an analyte present at relatively high background levels in blank (untreated) biological matrixes. Using a "surrogate analyte" approach, an endogenous analyte was quantitated in a variety of biological matrixes containing both very low (<10 ng/mL) and high (>2000 ng/mL) background levels of the desired analyte. This quantitative "surrogate analyte" approach was applied during the development of an HPLC/MS method for alpha-ketoisocaproic acid (KIC), which was identified as a potential biomarker for branched chain amino acid transferase inhibitor activity. Using deuterium-labeled KIC (d(3)) as a surrogate analyte, not an internal standard, to generate the calibration curve, the concentration of KIC in biofluid could be back-calculated based on the regression equation and response factor of KIC to KIC-d(3). In particular, this approach made it possible to prepare standards in control biofluid such as plasma, which greatly facilitated the process of method development. For the validated method, a linear range of 10-5000 ng/mL for KIC-d(3) was observed. Intraday and interday experimental accuracy, calculated as percent error, were in the range of < or =10% for KIC-d(3). This method is simple, rapid, and reliable for the quantitation of KIC in plasma, brain homogenate, cerebrospinal fluid, and other biological samples from discovery and pharmacological studies.
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Affiliation(s)
- Wenlin Li
- Bioanalytical Research, Department of Pharmacokinetics, Dynamics & Metabolism, Pfizer Global Research and Development, 2800 Plymouth Road, Ann Arbor, Michigan 48105, USA
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Pailla K, Blonde-Cynober F, Aussel C, De Bandt JP, Cynober L. Branched-Chain Keto-Acids and Pyruvate in Blood: Measurement by HPLC with Fluorimetric Detection and Changes in Older Subjects. Clin Chem 2000. [DOI: 10.1093/clinchem/46.6.848] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AbstractBackground: Measurement of keto-acids is important in various clinical situations. The aim of the present work was to develop a rapid HPLC method for the determination of keto-acids in human serum and to assess the concentrations of these acids in young adults and institutionalized elderly adults. This method was applied to the determination of blood keto-acid concentrations of young adults and institutionalized elderly people, divided into age groupsMethods: Four keto-acids (α-ketoisocaproate, α-ketoisovalerate, α-keto-β-methylvalerate, and pyruvate) were derivatized with o-phenylenediamine to give fluorescent derivatives. After the sample preparation step (75 min to prepare 20 samples), the derivatives were separated chromatographically on a reversed-phase column using a binary gradient.Results: The fluorometric detection of the four keto-acids was rapid, <12 min. The method is repeatable and reproducible: the CVs were <6% and <11%, respectively, for each of the keto-acids. We found no significant difference between males and females. Concentrations of the branched-chain keto-acids decreased after age 60 years, especially α-ketoisocaproate, which decreased ∼40%.Conclusions: The proposed method allows rapid and reliable measurement of keto-acids. The data demonstrate that changes in branched-chain keto-acids concentrations in serum occur with age.
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Affiliation(s)
- Karine Pailla
- Biochem Laboratory, Emile Roux Hospital, AP-HP, 1 Avenue de Verdun, 94456 Limeil-Brévannes Cedex, France
- Nutrition Laboratory, EA 2498, Paris V University, 4 Avenue de l’Observatoire, 75006 Paris, France
| | - Françoise Blonde-Cynober
- Biology Laboratory, Joffre-Dupuytren Hospital, AP-HP, 91211 Draveil Cedex, France
- Nutrition Laboratory, EA 2498, Paris V University, 4 Avenue de l’Observatoire, 75006 Paris, France
| | - Christian Aussel
- Biochem Laboratory, Emile Roux Hospital, AP-HP, 1 Avenue de Verdun, 94456 Limeil-Brévannes Cedex, France
- Nutrition Laboratory, EA 2498, Paris V University, 4 Avenue de l’Observatoire, 75006 Paris, France
| | - Jean-Pascal De Bandt
- Biochem Laboratory, Hôtel-Dieu Hospital, AP-HP, 1 Place du Parvis Notre-Dame, 75181 Paris Cedex 04, France
- Nutrition Laboratory, EA 2498, Paris V University, 4 Avenue de l’Observatoire, 75006 Paris, France
| | - Luc Cynober
- Biochem Laboratory, Hôtel-Dieu Hospital, AP-HP, 1 Place du Parvis Notre-Dame, 75181 Paris Cedex 04, France
- Nutrition Laboratory, EA 2498, Paris V University, 4 Avenue de l’Observatoire, 75006 Paris, France
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Kiba N, Muto M, Furusawa M. High-performance liquid chromatographic determination of branched-chain alpha-keto acids in serum using immobilized leucine dehydrogenase as post-column reactor. JOURNAL OF CHROMATOGRAPHY 1989; 497:236-42. [PMID: 2625460 DOI: 10.1016/0378-4347(89)80023-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- N Kiba
- Department of Chemistry, Faculty of Engineering, Yamanashi University, Kofu, Japan
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Smeaton TC, Owens JA, Robinson JS. Micro-method for measurement of branched-chain keto acid concentrations in plasma from sheep and man. JOURNAL OF CHROMATOGRAPHY 1989; 487:434-9. [PMID: 2723007 DOI: 10.1016/s0378-4347(00)83051-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- T C Smeaton
- Department of Obstetrics and Gynaecology, University of Adelaide, South Australia
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