Rapid and sensitive HPLC assay for simultaneous determination of procaine and para-aminobenzoic acid from human and rat liver tissue extracts

A sensitive and rapid high-performance liquid chromatography method has been developed for simultaneous determination of procaine and its metabolite p-aminobenzoic acid (PABA) from human and rat liver tissue extracts. The method has been validated according to ICH guidelines in terms of selectivity, linearity, lower limit of detection, lower limit of quantitation, accuracy, precision and recovery from human and rat liver tissue extracts. Chromatography was carried out on a Discovery (R) C-18 column using 10 mM ammonium acetate at pH 4.0 and acetonitrile as mobile phase. Retention times for procaine and PABA were 6.6 and 5.3 min, respectively. Linearity for each calibration curve in both tissue extracts was observed across a range from 10 mu M to 750 mu M for procaine and PABA. The lower limit of detection for both procaine and PABA was 5 mu M and the lower limit of quantitation was 10 mu M in both tissue extracts. The intra- and inter-day relative standard deviations (R.S.D.) for both procaine and PABA were < 6%. Recoveries of procaine and PABA from human and rat liver tissue extracts were determined by two different methods with a single-step protein precipitation technique being employed in both methods. Recoveries for both procaine and PABA were greater than 80% from both human and rat liver tissue extracts. (c) 2008 Elsevier B.V. All rights reserved.