Validation of two methods for the quantitative analysis of cocaine and opioids in biological matrices using LCMSMS

The proliferation of misuse of prescription and non-prescription opioids, in recent years, has caused an opioid epidemic in the United States. Forensic toxicology laboratories often encounter implications of abuse in both driving under the influence of drugs and death investigation cases. The Virginia Department of Forensic Science has seen over a 190% increase in the number of reported opioids in death investigation cases over the past several years. Traditionally, analyses are completed by individual drug class, which subsequently requires an individual case to be evaluated using multiple analytical techniques for comprehensive analysis. To ease the impact of increasing case submissions and case complexity, two liquid chromatography-tandem mass spectrometry (LCMSMS) methods for the quantitative analysis of opioids, cocaine, and cocaine metabolites in biological matrices have undergone a fit-for-purpose validation. The methods were compared to determine the advantages and disadvantages of each analytical technique. Two sample preparation techniques, protein precipitation and solid-phase extraction, were employed for quantitative validation. Validation aspects evaluated included accuracy and precision, sensitivity, linearity, matrix effects, recovery, carryover, interferences, dilution integrity, and post-extraction stability. The accuracy of the protein precipitation method ranged from 80 ± 3% to 101 ± 10%. The accuracy of the solid-phase extraction method ranged from 88 ± 9% to 119 ± 3%. Additionally, within-run and intermediate precision was within ±20% for both extraction techniques. Although ionization suppression was noted, it was determined to have minimal effect on the methods. The newly developed methods require less sample volume and combine four analytical techniques into one method, which significantly impacts laboratory productivity.