engleski

Quality assurance in drugs of abuse testing

Legal implications involved in the testing for drugs of abuse impose strict demands on the reliably and on an error-free operation of laboratories where such tests are performed. Hence the need for quality assurance (QA). A rigorous quality assurance programme consists of quality control and quality assessment. Quality control involves error checking and is supposed to validate laboratory data, whereas quality assessment involves evaluation of lab analytical functions, as well as monitoring of the analytical processes and verifying that they are within acceptable limits. This paper describes our participation in the programme for drugs of abuse testing, the so called UK National External Quality Assessment Schemes (UKNEQAS) organized by Cardiff Bioanalytical Services Ltd. Lyophilized urine samples are distributed in sets of 3 at quarterly intervals. They contain mixtures of drugs of abuse and metabolites: amphetamines, barbiturates, cocaine or metabolites, cannabinoides, benzodiazepines, opiates and non-opiate narcotics. For each test, a report of positive, negative, uncertain or a numeric result is given together with coded details of the technique used. An overall report of present or not found must be marked relative to the cut-off concentrations proposed by the scheme. A score is calculated for each analyte and for each of the twelve samples. There are two criteria of acceptable performance: return of >75% reports and satisfactory analytical performance. Poor performance is defined as an overall performance score of <75% in two successive distributions. Our own score has been 100%, so far. // The participation in external quality assessment should be mandatory for laboratories testing drugs of abuse to receive accreditation.

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