Determination of quinidine, dihydroquinidine, (3S) -3-hydroxyquinidine and quinidine N-oxide in plasma and urine by high-performance liquid chromatography
Nielsen, F.; Nielsen, K.K.; Brøsen, K.
Journal of Chromatography. B, Biomedical Applications 660(1): 103-110
ISSN/ISBN: 1572-6495 PMID: 7858702 DOI: 10.1016/0378-4347(94)00259-2
A specific and sensitive method for the quantitation of quinidine, (3S)-3-hydroxyquinidine, quinidine N-oxide, and dihydroquinidine in plasma and urine has been developed. The method is based on a single-step, liquid-liquid extraction procedure, followed by isocratic reversed-phase high-performance liquid chromatography, with fluorescence detection. After extraction from 250 microliters plasma and 100 microliters urine, the limit of determination is 10 nM and 25 nM, respectively. For the use as standards, commercially available quinidine was purified from dihydroquinidine; quinidine N-oxide was synthesized.