Simultaneous detection and quantification of acidic and basic drugs in serum toxicological screening: use of ion-pairing technique in liquid-liquid extraction

The toxicological screening, using the combination of high performance liquid chromatography with diode array ultraviolet detector and ion-pairing technique in liquid-liquid extraction, is an effective tool in the identification and quantification of the acidic and basic substances in a single run. The use of an ion-pairing technique in the conventional extraction shows the co-extraction of the uncharged and charged form of the analytes present in a serum sample. The stationary phase used is C-18-bonded phase. The mobile phase is acetonitrile--phosphate buffer (pH 3; 25 mM) containing 25 mM triethylammonium as ion-pairing agent. The analytical validation shows reproducible recoveries, good day-to-day repeatability and sensible results compatible with clinical and forensic use.