Short reverse phase HPLC method for 5-methoxy-2-mercaptobenzimidazole related substance estimation

Benzimidazole derivatives are wide interest because of their biological activity and clinical uses. Short and simple method was developed to control the "carry over impurity" in 5-methhoxy-2-mercaptobenzimidazole. This benzimidazole derivative was used in various drug substance syntheses. The proposed method was short (20 min run time) and validated as per the standard validation guidelines. Chromatographic separation was achieved in Inertsil ODS-3V (150mm long, 4.6 inner diameter and 5μm particle size). Compare to other C-18 columns, Inertsil column showed symmetry peak. Mobile phase A was 4.5 pH buffer of perchloric acid in water, and mobile phase B was acetonitrile that were used as eluent in gradient mode. The gradient program as follows: time (min)/A (v/v):B (v/v); T₀.₀/75:25; T₅.₀/75:25; T₁₂.₀/55:45; T_15.0/75:25, T₂₀.₀(/75:25; injection volume was 5μ1. Methanol : water (3:7) was used as a diluent. Sample preparation was 250μg/ml. Column temperature was set at 35°C. UV detection was made 302 nm. Linear response was observed between concentrations against response. LOQ, LOD of the 5-M-2-MB, and 2-MB are 0.015%, 0.010%, 0.006% and 0.005% respectively. Recovery percentage of 2-MB was observed 107 and 106 with good precision of <; 2% RSD.