Efficient MSPE based on MBCZ@DES composite coupled with LC-MS/MS for determining methcathinone in water and visualization mechanism study by density functional theory calculation

Abstract

In this work, single-factor and Box-Behnken design (BBD) experiments were utilized to optimize extraction process of methcathinone through magnetic solid phase extraction (MSPE). Magnetic biochar modified with ZIF-8 and deep eutectic solvent (DES) named MBCZ@DES was used as the magnetic adsorbent in the MSPE procedure. The successful preparation of adsorbent was demonstrated via various characterizations. The BBD optimization revealed excellent agreement between predicted and experimental values. The p-value of model is below 0.05, suggesting the significance of the model. Subsequently, MBCZ@DES-based MSPE coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for detecting methcathinone in water. Method validation demonstrated satisfactory performance with a linear calibration range of 1–200 μg/L (R² = 0.9999), limit of detection (LOD) at 0.137 μg/L, and quantitation accuracy reflected by recoveries of 93.83–95.31 %. Precision studies showed relative standard deviations (RSDs, n = 6) of 1.27–4.31 % for both intra-day and inter-day precision. The MSPE-LC-MS/MS method was successfully adopted to analyze actual water samples, obtaining desirable recoveries varying from 90.89 % to 98.84 %. Mechanisms exploration revealed that reaction mechanisms between MBCZ@DES and methcathinone primarily involved π-π interaction and hydrogen bonding. The insights of governing reaction mechanisms were further explored and verified by density functional theory (DFT) calculation in detail.