LC-MS-MS vs ELISA: Validation of a Comprehensive Urine Toxicology Screen by LC-MS-MS and a Comparison of 100 Forensic Specimens

Abstract

Toxicology laboratories commonly employ immunoassay methodologies to perform an initial drug screen on urine specimens to direct confirmatory testing. Due to limitations of immunoassay testing and the need to screen for a broader range of drugs with lower limits of detection at a lower cost, mass spectrometry screening techniques have gained favor in the toxicology field. A liquid chromatography–tandem mass spectrometry (LC-MS-MS) urine screening panel was developed and validated for 52 drugs and metabolites. A simple dilute-and-shoot with enzymatic hydrolysis technique was utilized to prepare the urine specimens for analysis. Limit of detection, interference, ionization suppression/enhancement, carryover and stability of processed specimens were assessed during validation. To evaluate the toxicological results obtained from utilizing the LC-MS-MS in comparison with the laboratory’s current enzyme-linked immunosorbent assay (ELISA) panel, 100 authentic urine specimens from suspected driving under the influence and drug-facilitated crime cases were analyzed using both methodologies and the results were compared. In addition, the cost of each methodology was evaluated and compared. The validated LC-MS-MS method had limits of detection that were equal to or lower than the concentrations validated for ELISA cutoffs, had fewer exogenous interferences, and the cost of screening per specimen was reduced by ~70% when compared to ELISA. Comparing the toxicology results of forensic urine specimens demonstrated that by only using ELISA, the laboratory was unable to detect benzoylecgonine in 26%, lorazepam in 33% and oxymorphone in 60% of the positive specimens. Additional analytes detected using the LC-MS-MS method were zolpidem and/or metabolite, gabapentin, tramadol and metabolite, methadone and metabolite, meprobamate and phentermine. The results of the validation, the toxicological result comparison and the cost comparison showed that the LC-MS-MS screening method is a simple, sensitive and cost-effective alternative to ELISA screening methods for urine specimens.

Developing and Evaluating the Greenness of a Reliable, All-in-One Thin-Film Microextraction Protocol for Determining Fentanyl, Methadone, and Zolpidem in Plasma, Urine, and Oral Fluid

“…LOD values below 1 ng mL −1 obtained for most combinations of matrices and analytes allowed for the precise and accurate measurement of the target analytes in biological matrices that satisfied the minimum sensitivity requirements stipulated by the WADA, SAMHSA, and EWDTS. Additionally, the method’s analytical performance significantly exceeded that of routinely employed immunoassays, which have LLOQ values of 2 ng mL −1 , 300 ng mL −1 , and 25 ng mL −1 for fentanyl, methadone, and zolpidem, respectively [ 33 ]. Figure 4 presents the chromatograms at the lower quantification limits.…”

New psychoactive substances (NPS) escape routine drug testing: a case report of phenibut

“…In the current circumstances of availability and use of a variety of NPS, LC-MS/MS analysisunlike most immunoassayswill simultaneously test for many drugs to improve treatment by correctly identifying the ingested substances. Compared to immunoassays, LC-MS/MS has lower limits of detection, lower costs of screening per specimen, and identifies a greater number of substances [12].…”

Implementation of Mathematical Models to Predict New Cannabis Use by Urine Drug Testing: It Is Time to Move Forward

“…Some argue that the financial cost of urine testing limits its routine use and that clinicians should instead rely on self-reporting and structured interview strategies. However, the trend in application of high-performance liquid chromatography and tandem mass spectrometry for automated urine analysis, without the need for initial hydrolysis ( 17 , 18 ), will probably lower the cost of clinical toxicology analysis ( 19 ). With access to an online evidence-based program to differentiate new use from residual excretion of cannabinoids, the utility of THC-COOH/CREA as an accurate and valuable biomarker could be improved.…”