A systematic comparison of four different workup procedures for systematic toxicological analysis of urine samples using gas chromatography-mass spectrometry.

Sample preparation for systematic toxicological screening analysis (STA) in urine by gas chromatography-mass spectrometry (GC-MS) generally involves cleavage of conjugates by acid hydrolysis (Hy) or enzymatic hydrolysis (Gluc) followed by liquid-liquid extraction (LLE) or solid-phase extraction (SPE), and derivatization, e.g., acetylation (Ac).