Comparison of high-performance and thin-layer chromatographic methods for the assay of lidocaine.

Reversed-phase high-performance liquid chromatographic (HPLC) and thin-layer chromatographic (TLC)-UV densitometric methods were developed for the quality control of lidocaine hydrochloride bulk drug and its injection solutions. The HPLC method used an RP-18 reversed-phase column with methanol-water-1% phosphoric acid-hexylamine (30:70:100:1.4, v/v/v/v) as the mobile phase and detection at 254 nm, with a capacity factor k' = 0.8. The TLC-UV densitometric method was performed on silica gel plates using diisopropyl ether-acetone-diethylamine (85:10:5, v/v/v) as the developing solvent and UV detection at 254 nm. The response was linear up to 10 micrograms ml-1 (HPLC) and 8 mg ml-1 (TLC). The RSD of the peak areas was 1.71% for HPLC and 0.55% for TLC, with recoveries in the range 99.6-100.2% for HPLC and 99.2-100.7% for TLC.