An Inhibitory Kinetic Method for the Methionine Determination

Document Type : Regular Article


1 Department of Chemistry, GLA University, Mathura, 281006, U.P., India

2 Shri Ramswaroop Memorial University, Barabanki, 222502, U.P., India



A fast and reproducible method is proposed for the kinetic determination of methionine (MET). The method depends on the inhibitory property of methionine, which reduces the Hg2+ catalyzed imitation of cyanide from [Ru(CN)6]4- with pyrazine via forming a stable complex with Hg2+. Spectrophotometric measurements were carried out by recording the absorbance at 370 nm (λmax of [Ru(CN)5 Pyrazine]3- complex) at a fixed time of 12 min under the optimized reaction conditions with [Pyrazine] = 6.5 × 10-4 M, I = 0.05 M (KNO3), Temp = 45.0 ± 0.2 o C, pH = 4.00 ± 0.03, [Hg2+] = 7.5 × 10-5 M and [Ru(CN)64-] = 5.25 × 10-5 M [46]. With the proposed method, methionine can be determined quantitatively down to 2.5 × 10-6 M. This methodology can be effectively used for the rapid quantitative estimation of MET in the pharmaceutical samples with good accuracy and reproducibility.

Graphical Abstract

An Inhibitory Kinetic Method for the Methionine Determination