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High sensitivity determination of the remoxipride hydroquinone metabolite NCQ‐344 in plasma by coupled column reversed‐phase liquid chromatography and electrochemical detection
Author(s) -
Nilsson Lars B
Publication year - 1998
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/(sici)1099-0801(199803/04)12:2<65::aid-bmc722>3.0.co;2-f
Subject(s) - chemistry , chromatography , metabolite , hydroquinone , high performance liquid chromatography , extraction (chemistry) , quantitative analysis (chemistry) , reversed phase chromatography , analytical chemistry (journal) , organic chemistry , biochemistry
An HPLC method for the determination of NCQ‐344, a remoxipride metabolite with a hydroquinone structure, in human plasma is described. Special precautions for the sampling were necessary as the compound rapidly decomposes. An efficient clean‐up of the plasma samples was necessary to make use of the inherent sensitivity of the electrochemical detector. This was accomplished by a fast and simple liquid–liquid extraction at pH 7.05 combined with further cleaning on‐line by using a short cyanopropyl column as the first column in a column switching system. A heart‐cut from the cyanopropyl column containing the NCQ‐344 fraction was then injected onto the analytical octadecyl silica column and NCQ‐344 was detected at an oxidation potential of 0.70 V. The absolute recovery was >95% and concentrations down to 0.10 nM could be determined with acceptable precision. The NCQ‐344 levels in a limited number of samples from patients given remoxipride were found to be between 0.10 and 1 nM. The remoxipride concentrations in the same samples were 5 000–20,000 nM. © 1998 John Wiley & Sons, Ltd.