The Challenging Analysis of Drug Testing

When testing the 5 groups of drugs, GC/MS is done to confirm drugs in the urine samples. This however, tends to be quite challenging. If the laboratory is experienced, it can easily fulfill the required criterion which is needed to analyze different drugs. Many laboratories use similar instruments to perform GC testing. The liquid-liquid and solid-phase extractions are done quite similarly in different laboratories. Derivatization – chemical modification of drugs to analyze GC column is done for many drugs except phencyclidine. Laboratories also use 1 or 2 variants to analyze compounds. However, it is challenging because donor samples have different substances in their urine samples due to varying diet, supplements and medication differences. These often cross reacted to form different compounds. For instance, ephedrine or pseudoephedrine can react under GC/MS test to form methamphetamine. This concentration of methamphetamine cannot be deemed as positive methamphetamine unless 200 ng/mL of amphetamine is present.  This eliminates chances of false positive results due to artifacts of testing procedures. Normally, laboratories do not find any difficulties to meet the criteria, but when other drugs are present at high concentration, it becomes quite difficult to meet the criterion at 40% of cutoff range. This happens more so especially when some drugs react in the GC process, close to their retention time, yielding metabolites that pose a great challenge while performing these tests.

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