Functionalized toothpicks for solid-phase microextraction of drugs from oral fluids

Efficient extraction techniques with high selectivity and sensitivity are critical for drug analysis in biological matrices. Traditional methods often face challenges when dealing with semi-polar and ionic drugs, necessitating the development of improved sorbents. To address this issue, we propose the use of carboxymethylated wooden toothpicks (c-WTs) as a novel sorbent for solid-phase micro-extraction (SPME). This approach aims to improve drug extraction from oral fluids, offering a more effective and sustainable solution compared to conventional sorbents.

Wooden toothpicks were modified through sodium chloroacetate oxidation under mild conditions, introducing carboxyl groups that enhance analyte-sorbent interactions via electrostatic forces. Characterization via infrared spectroscopy and scanning electron microscopy confirmed the successful derivatization, showing an increase in surface roughness compared to unmodified toothpicks. The optimized SPME method was applied to extract a range of 22 drugs, including amphetamines, opioids, benzodiazepines, and cannabinoids, from oral fluids. The validation of the method demonstrated excellent performance, with recovery rates ranging from 68 to 120 %. Precision was high, with relative standard deviations (RSD) below 10 %. The method also exhibited low limits of quantification (1-5 μg L^-1) when analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), indicating its potential for reliable and sensitive drug analysis in biological matrices.

This study presents an innovative, sustainable approach for drug extraction using natural-based sorbents. The use of c-WTs offers a cost-effective, selective, and environmentally friendly alternative to traditional methods. This work contributes to the development of efficient SPME techniques for complex biological samples, advancing analytical methodologies in forensic and clinical applications.