Reactivity of EMIT serum barbiturate assay reagents: potential application for the quantitation of selected barbiturates.

The reactivity of EMIT serum barbiturate assay reagents toward barbiturate test compounds was investigated. Reactivity was determined by the C5 substituents on the barbiturate ring and O/S substitution (barbituric/thiobarbituric acid derivatives). Reagents were more reactive toward a 5,5-substituted barbiturate than toward its hydroxylated analogue. EMIT reactivity could be linearized vs. concentration of test compound, allowing for quantitative analysis in serum or plasma.