Validation of High-Performance Liquid Chromatographic—Mass Spectrometric Method for the Analysis of Lidocaine in Human Plasma

A sensitive and simple liquid chromatography‐tandem mass spectrometry method is developed and validated for the determination of lidocaine in human plasma. Bupivacaine is used as an internal standard, and the plasma extraction is performed by a simple liquid‐liquid extraction. The limit of quantitation (LOQ) is 0.5 ng/mL with a signal-to-noise ratio greater than 5. The calibration curve is linear from 0.5 to 250 ng/mL with an r2 greater than 0.99. The coefficients of variation for within- and betweenassay imprecision, including LOQ, are ≤ 13% and ≤ 8%, respectively. The percentage of inaccuracy for within- and between-assay, including LOQ, are ≤ 9% and ≤ 5%, respectively. The absolute recovery of lidocaine and bupivacaine are greater than 84% and 82%, respectively. The higher sensitivity and accuracy of this method allow the measurement of low concentrations of lidocaine in plasma from a clinical study of topically applied lidocaine in healthy subjects.