Analysis of 15 anti-obesity drugs in urine using thermal-assisted paper spray mass spectrometry

Abstract

Anti-obesity drugs, used to suppress appetite and reduce fat absorption, have been circulated and traded illegally worldwide. The traditional methods of liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) for analyzing these drugs in in vivo samples require complex sample pretreatment and time-consuming procedures. To address this issue, a thermal-assisted paper spray mass spectrometry (PS-MS) method was developed in this study to analyze anti-obesity drugs in raw urine. By incorporating a heat source and optimizing the spray solvent and paper substrate, this technique demonstrates reduced matrix effect and higher sensitivity compared to traditional PS-MS methodology for direct analysis of anti-obesity drugs in urine samples. A temperature range of 100–200 °C can be set for screening anti-obesity drugs in urine samples, with the flexibility to adjust the temperature according to the specific drug being analyzed. The limits of detection (LODs) for these 15 anti-obesity drugs in urine ranged between 1 and 500 ng mL⁻¹. Furthermore, the thermal-assisted PS-MS method exhibited good linearities (R², 0.9903–0.9997) within the range from 10–100 to 1000 ng mL⁻¹ for the direct quantitation of anti-obesity drugs in urine samples with an internal standard. Therefore, the thermal-assisted PS-MS technique may provide a novel approach for the direct analysis of drugs in complex samples.