A micromethod for the isolation of drugs from blood using amberlite XAD-2

The extraction of drugs from small blood samples (1 ml or less) for subsequent quantitative determination is described. Isolation was carried out by adsorption of the drugs to Amberlite XAD-2 resin utilizing a batch procedure that enabled the simultaneous extraction of up to 200 samples in approx. 5 hours. A new desorption technique yielded extracts of high purity that could be used directly for gas chromatographic or radioimmunological determinations, even if hemolyzed or putrid blood was to be examined. The following 26 substances were quantitated after addition to postmortem blood speciments at concentrations of 1-10 microgram/ml: tilidine, diphenhydramine, dibenzepine, imipramine, chlorpromazine, amphetamine, pentazocine, phenacetin, methaqualone, meprobamate, parathion, diazepam, digoxin, beta-methyldigoxin, carbromal, glutethimide, amobarbital, pentobarbital, cyclobarbital, phenobarbital, diphenylhydantoin, carbutamide, tolbutamide, glycodiazin, tolazamide and chlorpropamide. Thereby recoveries of 60-100% could be achieved. The reproducibility of the procedure was satisfactory as demonstrated by coefficients of variation of 3.7-8%.