Validation of an enantioselective analysis for (l)-pidolic acid by chiral gas chromatography with derivatization

A sensitive and rapid analytical method has been validated for the enantiomeric purity determination of l-pidolic acid, a biological lactam and metabolite of glutamic acid commonly found in urine, skin, bones, brain and is available commercially as a food supplement. An efficient, two-step achiral derivatization was implemented which consisted of an alkylation step (using HCl-IPA) followed by an acylation step (using TFAA) of the carboxy and amide functional groups. This allowed detection with high sensitivity using gas chromatography with flame ionization detection. The described procedure employs a CP-Chiralsil-L Val column (25m×0.25mm) at a constant flow rate of 1.5mLmin(-1), a gradient temperature program from 80°C to 160°C and an injector and detector temperature of 250°C. The proposed method was validated according to ICH Q2 standards and included such parameters as specificity, system precision, analyst repeatability, intermediate precision, accuracy, linearity, LOD/LOQ and solution stability.