Brewer’s spent grain as a potential sorbent for toxicology methods: Application to antidepressant analysis in urine

Abstract

The use of antidepressants is well-documented for several health conditions. The determination of these drugs in biological fluids is often important in intoxication cases. However, appropriate sample preparation needs to be employed, such as dispersive liquid phase microextraction (DSPME). Therefore, this study aimed to develop a method for the determination of antidepressants in urine using Brewer’s spent grain (BSG) as sorbent in a DSPME procedure, followed by GC-MS analysis. In this methodology, only 500 µL of urine was required, alongside 15 mg of BSG as the sorbent for the DSPME technique. Desorption step was performed with 500 µL of ethyl acetate:MTBE solution (1:1, v/v), followed by evaporation of the organic layer, reconstitution in acetonitrile and injection into the analytical system. BSG was further characterized by several analytical techniques. The DSPME procedure was optimized using multivariate strategies, and the method was fully validated according to proper guidelines. Lower limits of quantitation (LLOQ) were set between 50 and 200 ng/mL, while linearity was achieved over the specified range of LLOQ to 5000 ng/mL, with R² ≥ 0.99. Additionally, the method was applied to the analyses of 109 urine samples. Of these, 76 were positive for at least one antidepressant, with the most prevalent being nortriptyline, amitriptyline, and fluoxetine. This study is the first to report the use of BSG as a sorbent for DSPME, demonstrating good efficiency as indicated by the analytical figures of merit. Moreover, the method proved to be applicable in real poisoning case samples. The analytical performance, combined with advantages such as high throughput and a green profile, suggests this method as a valuable alternative for toxicological laboratories.