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Biochip array technology immunoassay performance and quantitative confirmation of designer piperazines for urine
Marisol S Castaneto1, Allan J Barnes, Marta Concheiro
1Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, 21224, USA.
Analytical and Bioanalytical Chemistry
|April 24, 2015
Summary
A biochip array technology immunoassay effectively screened for designer piperazines in workplace urine, with optimized cutoffs improving performance. Most positive results were linked to legitimate trazodone prescriptions.
Area of Science:
- Forensic Toxicology
- Analytical Chemistry
- Pharmacology
Background:
- Designer piperazines are emerging novel psychoactive substances (NPS) requiring efficient identification methods.
- Existing high-throughput screening methods for piperazine NPS are limited.
- Workplace drug testing necessitates reliable detection of these substances.
Purpose of the Study:
- To evaluate the performance of a biochip array technology (BAT) immunoassay for detecting phenylpiperazines (PNP) and benzylpiperazines (BZP) in urine specimens.
- To assess the impact of optimized antibody cutoffs on the immunoassay's specificity and sensitivity.
- To analyze the prevalence of piperazine NPS in a large cohort of workplace urine samples.
Main Methods:
- A biochip array technology (BAT) immunoassay was used to screen 20,017 workplace urine specimens for PNPI, PNPII, and BZP.
- Presumptive positive and randomly selected negative specimens were confirmed using liquid chromatography-high-resolution mass spectrometry (LC-HRMS).
- Assay performance was evaluated at recommended and optimized antibody cutoffs.
Main Results:
- The BAT immunoassay demonstrated good assay limits of detection (2.1–6.3 μg/L) and linearity (R² > 0.99).
- At optimized cutoffs (25 μg/L PNPI, 42 μg/L PNPII, 100 μg/L BZP), specificity ranged from 21.1% to 91.4% and efficiency from 27.0% to 91.6%.
- Of 840 presumptive positives, 9.3% were confirmed, primarily for 1-(3-chlorophenyl)piperazine (mCPP), a trazodone metabolite. Two presumptive negatives were confirmed positive for mCPP and BZP.
Conclusions:
- The Randox BAT immunoassay is a viable high-throughput screening tool for urinary piperazines, with improved performance at elevated antibody cutoffs.
- The study identified mCPP and BZP in workplace urine, with most positive cases likely stemming from legitimate trazodone prescriptions.
- Further development of high-throughput screening methods is crucial for identifying emerging piperazine NPS.
