Determinations of new psychoactive substances in biological matrices with focus on microextraction techniques: a review of fundamentals and state-of-the-art extraction methods

Purpose

This review article provides a detailed discussion of studies in which microextraction techniques are applied for the determination of new psychoactive substances (NPS) in biological samples. Definitions and classifications of NPS are highlighted as well as the fundamentals of the microextraction techniques used in their analyses.

Methods

A complete literature search was carried out with PubMed, Scopus and the World Wide Web using relevant keywords, e.g., NPS, microextraction and biological fluids.

Results

The determinations of NPS in biological samples remain a challenge for analytical laboratories due to its wide diversity of compounds. The utilization of microextraction techniques in this context is still not many. However, the 96 deep well plate for microextraction and microextraction by packed sorbent (MEPS) can be highlighted as the most explored configurations. Microextraction approaches have the potential to be further improved and optimized to provide rapid and low-cost analyses with reliable results.

Conclusions

There is a wide scope of microextraction techniques to be explored in the field of toxicology and NPS determinations. These techniques are compatible with recent trends of automation and miniaturization, which can enable a straightforward workflow for NPS analyses.

     

Assessment of a natural extraction phase in disposable pipette extraction coupled with the sub-minute determination of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in human urine by fast-GC-FID

The compound 11-nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) consists of the major metabolite of tetrahydrocannabinol (THC) in human urine. Analysis of this compound exhibits an important role in forensic scenario; therefore, several analytical methods have been developed for this purpose. In this study, for the first time, a biosorbent-based disposable pipette extraction was developed for the determination of THC-COOH, using a simple and high-throughput sample preparation technique. In addition, a rapid instrumental analysis was achieved by fast-gas chromatography coupled with flame ionization detection (fast-GC-FID). Different biosorbents were examined, including cork, moringa and bract. The method was optimized through univariate and multivariate designs with the conditions comprised of 15 mg of cork as the extraction phase, pH maintained at 2.5 with 8 cycles of extraction of 60 s each, and 1 cycle of 5 s for the desorption step with a mixture of acetonitrile:methanol (ACN/MeOH). Limit of detection was 0.21 ng mL^?1 and the limit of quantification was 0.73 ng mL^?1, with a linear range from 5 to 100 ng mL^?1 and coefficient of determination (R²) 0.9905. The relative recoveries ranged from 96 to 108%, intraday and interday precisions were lower than 13%. Different samples were subjected to the extractions using the method developed with four positive samples for the analyte.     

Simple and straightforward analysis of cannabinoids in medicinal products by fast-GC–FID

Forensic Toxicology -