Rapid chiral separation and impurity determination of ropivacaine and bupivacaine by Densitometry-HPTLC, using mucopolysaccharide as chiral mobile phase additive

Abstract

Enantio separation of the local anesthetic drugs; ropivacaine (Rop), bupivacaine (Bup) and potential organic impurities (2,6-Dimethylaniline, 2,6-DMA) were accomplished on HPTLC using mucopolysaccharide selector (Chondroitin) as chiral mobile phase additive (CMPA). The enantioseparation was achieved in acetonitrile:water:methanol (16:3:1, v:v:v) containing 0.25% chondroitin as chiral mobile phase additive. The influence of separation conditions, including type and concentration of chiral selector, organic modifiers and temperatures on enantioseparation were evaluated. The enantioselective HPTLC method was validated to control the enantiomeric purity of the (S)-enantiomers (S-Rop and S-Bup); the active ingredients contained in drug products. In these conditions, linearity over the concentration range, 1.0-10.0 µg/spot for each (R)-enantiomer and 1.0-8.0 µg/spot for 2,6-DMA main organic impurity were obtained. The detection limits are less than 0.6 µg/spot of chiral and organic impurities. The intra and inter-day assay precision was less than 3.0% (RSD%).