Proficiency testing for psychoactive substances in Italy

This paper describes the general design and main results of the Italian pro ficiency testing program for the analysis of psychoactive substances in uri ne, a longterm initiative created in 1995 on an educational basis and chara cterized by an innovative internet-based service for data exchange between laboratories and the organizing body. Batches of six urine samples, validat ed by reference laboratories, are sent every 3 months to participating labo ratories, which may choose which classes of substances to test from those p lanned by the program panel and, within those classes, which type of analyt ical commitment to work on: identification of just one class (Option 1), id entification of single substances (Option 2), or identification and quantif ication of single substances (Option 3). Comprehensive periodical reports a nd annual reports are provided to participants with evaluation of their per formance and an annual workshop is organized to discuss technical-scientifi c topics related to clinical, forensic and analytical toxicology. About 200 laboratories currently participate in the program and a total of 67,059 an alyses have been carried out since 1995. The mean percentage of correct res ults was 96.8%, with a yearly improvement of about 0.4%. The best average f alse positive and false negative rates were obtained for methadone (0.2% an d 2.1% respectively) and cocaine (0.3% and 2.2%). The worst average false p ositive rates were obtained for amphetamines and opiates (3.2% and 5.0%) an d worst average false negative rates for amphetamines, barbiturates and can nabinoids (17.4%, 30.7% and 19.9%).