Simultaneous determination of procaine, lidocaine, ropivacaine, tetracaine and bupivacaine in human plasma by high-performance liquid chromatography.

A simple and sensitive high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method has been developed and validated for simultaneous quantification of five local anesthetics in human plasma: procaine, lidocaine, ropivacaine, tetracaine and bupivacaine. In an ice-water bath, 500μL plasma sample, containing 100μg/mL neostigmine methylsulfate as anticholinesterase, was spiked with carbamazepine as internal standard and alkalized by sodium hydroxide. Liquid–liquid extraction with ethyl ether was used for plasma sample preparation. The chromatographic separation was achieved on a Kromosil ODS C18 column with a mobile phase consisting of 30mM potassium dihydrogen phosphate buffer (0.16% triethylamine, pH adjusted to 4.9 with phosphoric acid) and acetonitrile (63/37, v/v). The detection was performed simultaneously at wavelengths of 210 and 290nm. The chromatographic analysis time was 13min per sample. The calibration curves of all five analytes were linear between 0.05 and 5.0μg/mL (r2≥0.998). Precision ranged from 1.4% to 7.9% and accuracy was between 91.7% and 106.5%. The validated method is applicable for simultaneous determination of procaine, lidocaine, ropivacaine, tetracaine and bupivacaine for therapeutic drug monitoring and pharmacokinetic study.