Analysis of plasma cyanate as 2-nitro-5-thiocarbamylbenzoic acid by high-performance liquid chromatography

A method for the determination of cyanate concentration in blood plasma over the range 1 to 1000 microM is presented. Cyanate present in the dried residue of acetone-deproteinized plasma is converted to a chromophoric thiocarbamyl derivative by addition of pH 3.0-buffered thionitrobenzoic acid. The derivative is then analyzed by reversed-phase high-performance liquid chromatography with detection at 313 nm, near the absorption maximum. Carbamyl thionitrobenzoic acid peak height is quantified by comparison to a standard curve made by analysis of plasma samples to which known quantities of cyanate have been added. This technique is sensitive and linear with respect to cyanate concentration, and is faster than other reported methods; sample analysis and column regeneration are accomplished within 20 min.