High sensitivity determination of the remoxipride hydroquinone metabolite NCQ-344 in plasma by coupled column reversed-phase liquid chromatography and electrochemical detection

Nilsson, L.B.

Biomedical Chromatography Bmc 12(2): 65-68


ISSN/ISBN: 0269-3879
PMID: 9568272
DOI: 10.1002/(sici)1099-0801(199803/04)12:2<65::aid-bmc722>3.0.co;2-f
Accession: 008772978

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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.