An LC-MS/MS based screening method for cannabinoids, opiates, amphetamines, cocaine, benzodiazepines and methadone was developed for the analysis of human serum, urine and post-mortem blood and discussed as an effective alternative to immunoassay based screening methods. Two mass spectrometric systems with differences in sensitivity common known were used for method validation. A simple protein precipitation was applied for a sample volume of 100 lL analysed using a Luna 5 mm C18 (2) 100 A, 150 mm x 2 mm analytical column and two mobile phases consisting of A (H2O/methanol = 95/5, v/v) and B (H2O/methanol = 3/97, v/v), both with 10 mM ammonium acetate and 0.1% acetic acid. The results achieved demonstrated that the method presented fulfils the recommendations for qualitative screening methods and can be applied successfully in the analysis of real samples. (C) 2017 Elsevier B.V. All rights reserved.