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BioMed Research International
Volume 2013 (2013), Article ID 678476, 7 pages
http://dx.doi.org/10.1155/2013/678476
Research Article

Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with Vitamin Deficiency

1Clinical Laboratories, Yuan's General Hospital, Kaohsiung 802, Taiwan
2Translational Research Laboratory, Cancer Center, Taipei Medical University Hospital, Taipei 110, Taiwan
3Clinical Laboratories, Chang Gung Memorial Hospital, Kwei-Shan 333, Taiwan
4Department of Food Science, National Penghu University of Science and Technology, Magong, Penghu 880, Taiwan
5Department of Radiation Oncology, School of Medicine, Taipei Medical University, Taipei 110, Taiwan
6Cancer Center and Department of Radiation Oncology, Taipei Medical University and Hospital, Taipei 110, Taiwan
7Division of Clinical Biochemistry, Graduate Institute of Medical Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan

Received 20 June 2013; Accepted 16 August 2013

Academic Editor: Natasa Tosic

Copyright © 2013 Chi-Fen Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0 mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan ( ), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15 μmole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC’s AST/B6 functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6 deficiency-associated hyperhomocysteinemic condition.