GLC determination of aprindine in human plasma using a nitrogen--phosphorus flame-ionization detector

A procedure for the determinations of aprindine in human plasma was developed. After the addition of N,N-diethyl-N'-(1,2,3,4-tetrahydro-2-naphthyl)-N'-phenyl-1,3-propanediamine as an internal standard, the plasma was buffered to pH 8.0, and the drug and the internal standard were extracted into ethyl acetate-hexane (9:1 v/v). The compounds then were extracted from the organic phase into 0.02 N HCl. The acidic solution was made basic with 0.2 M tribasic sodium phosphate, and aprindine and the internal standard were extracted into a small volume of hexane. The compounds were analyzed by GLC using a nitrogen--phosphorus flame-ionization detector. The drug concentration and instrument response were linear for 0.10--1.00 microgram of aprindine/ml, the slope was 1.1416 (0.0141), the y intercept was 0.0096 +/- 0.0082, and the correlation coefficient was 0.99960 +/- 0.00002. The sensitivity of the method was 0.02 microgram of aprindine/ml. The within-day coefficient of variation was 9.50, 3.14, and 2.21% for 0.05, 0.20, 0.40, and 0.80 microgram of aprindine/ml, respectively. The between-day coefficient of variation was 17.4, 3.40, 2.07, and 1.54% at the same concentrations. Total precision values of 19.9, 4.60, 4.26, and 2.69% were obtained. The overall relative error of the method +1.33, +2.00, -0.07, and +0.25% at these concentrations.