Overcoming fiber degradation: A green headspace solid-phase microextraction method with on-fiber derivatization for urinary amphetamines

• Developed a green HS-SPME method for simultaneous ATS analysis in urine. • The critical role of on-fiber derivatization was evaluated. • Experimental study revealed polymer film deterioration during on-fiber derivatization. Amphetamine-type stimulants (ATS) are the second most abused class of drugs worldwide after cannabis, making their reliable analysis in biological matrices a critical necessity. An eco-friendly headspace solid phase microextraction (HS-SPME) method was developed to sensitive and selective detection of amphetamine (AMP), methamphetamine (MET), 3,4-methylenedioxy amphetamine (MDA), and 3,4-methylenedioxy methamphetamine (MDMA) in urine using gas chromatography-mass spectrometry (GC-MS). The critical effect of derivatization on the fiber was evaluated. The Plackett-Burman design was used to optimize the method by screening the main parameters affecting its performance, and the method was validated. The alignment of the proposed method with the principles of green chemistry was evaluated using the AGREE software. Three acylation agents were compared for method performance, and trifluoroacetic anhydride (TFAA) proved the most suitable. Fiber degradation was prevented by using less derivatization reagent, thereby facilitating the complete desorption of analytes from the fiber. 10 min. adsorption time, 80°C derivatization temperature, and 1 min. of derivatization time gave the optimum results. Sensitive and selective detection of ATS in urine was achieved in the range of 25-2000 ng/mL. Accuracy ranged from 72.8% to 113.6%. A simple, reliable, and efficient method based on HS-SPME for the simultaneous determination of ATS in urine samples. Deterioration of the polymeric stationary film during the on-fiber derivatization was demonstrated experimentally. The reduced volume of acylation reagent effectively mitigated fiber degradation and yielded well-defined chromatographic peaks for all target ATS, likely by facilitating the desorption of strongly adsorbed analytes.