Fluorescence detection of mexiletine and its p-hydroxylated and hydroxymethylated metabolites in human plasma and urine by high-performance liquid chromatography using post-column derivatization with o-phthalaldehyde
Tateishi, T.; Harada, K.; Ebihara, A.
Journal of Liquid Chromatography 17(3): 659-671
1994
ISSN/ISBN: 0148-3919 DOI: 10.1080/10826079408013167
Accession: 008694260
A liquid chromatographic procedure for the simultaneous determination of mexiletine and two major metabolites, p-hydroxymexiletine and hydroxymethylmexiletine, in plasma and urine is described. A reversed-phase ion-pair C-18 column is used with gradient elution using post-column fluorescence derivatization with o-phthalaldehyde. The lower limits of detection are 2 ng/ml for mexiletine and p-hydroxymexiletine and 5 ng/ml for hydroxymethylmexiletine. Enzymatic hydrolysis of conjugate forms of oxidative metabolites in urine samples was also performed. The coefficients of variation for replicate assay of spiked samples were uniformly less than 10% for all the analytes.