Development of an HPLC method for the determination of mexiletine in human plasma and urine by solid-phase extraction

A sensitive and specific high-performance liquid chromatography (HPLC) method has been developed and validated for the quantification of mexiletine (MEX) in human plasma and urine. It uses solid-phase extraction (SPE) followed by an automated reversed-phase HPLC with a pre-column derivatization with 4-chloro-7-nitrobenzofurazan (NBD-CI) and UV–vis Absorbance detection. The process was set as: the UV–vis Absorbance wavelength was set at 458 nm. Chromatographic separation was performed on a Phenomenex-C18 Column (Aqua, 150 mm × 4.6 mm i.d. with 5 μm particle size) with the mobile phase consisting of acetonitrile and water (80:20, v/v), and the flow rate was set at 1.0 mL min−1. Calibration of the overall analytical procedure gave a linear signal (r > 0.9998) over a MEX concentration range of 0.2–2.0 μg mL−1 in human plasma and urine. The detection limit in plasma and urine was 0.1 μg mL−1. Intra- and inter-day precision of the assay at three concentrations within this range were 0.31–2.50%. The high specificity and sensitivity have been achieved by this fast method (total run-time <6 min). The method has been successfully validated in human plasma and urine and it has been shown to be precise, accurate and reliable.