Determination of substances of abuse in biological fluids by GC/MS using chemical ionization with acetonitrile

GC/ms is an important method to determine drugs in biological fluids. For each of the most commonly used drugs a methanolic solution (100 micrograms/ml) was prepared; 30 microliters of each solution was evaporated using nitrogen flow and than diluted in 100 microliters of a derivatizing mixture constituted by MSTFA and toluene (30/70). After a short reaction time at room temperature 1 ml of each solution was injected into a SE-52 column (15 m x 0.25 mm) using chemical ionization with acetonitrile. This method has a good signal/noise ratio and is very useful in screening techniques.