Determination of cysteine in human plasma by high-performance liquid chromatography and ultraviolet detection after pre-column derivatization with 2-chloro-1-methylpyridinium iodide.
This paper describes the development and validation of a reversed-phase HPLC method with isocratic conditions for the analysis of total cysteine in human plasma. The essential steps in the assay include derivatization of cysteine via thiol group with 2-chloro-1-methylpyridinium iodide (CMPI), separation of the formed cysteine S-pyridinium derivative from endogenous thiol derivatives, usually present in biological samples, by ion-pair reversed-phase HPLC, and ultraviolet detection. Free cystine and protein-bound cysteine are converted to their reduced counterpart by the use of 2-mercaptoethanol. The standard curve is linear over the concentration range from 20 to 300 nmol ml(-1). The recoveries are from 93.9 to 105.9% and imprecision was at most 2.5%. Optimal conditions are determined for all steps of the analytical procedure.
Chwatko
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G
Department of Environmental Chemistry, University of Łódź, 163 Pomorska Street, 90-236 Łódź, Poland.
Bald
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E