Miniature mass spectrometer-based point-of-care assay for measuring three psychiatric drugs in human plasma and whole blood.

Developing a rapid, simple method to detect psychiatric drug concentrations is essential, as it facilitates long-term monitoring of treatment efficacy and is critical for managing drug poisoning in clinical settings due to abuse or accidental overdose. Conventional laboratory-based assays used for monitoring psychiatric medications often demonstrate prolonged processing times, leading to considerable delays in adjusting treatment regimens. To address this, this study introduced a point-of-care testing (POCT) approach using a miniature mass spectrometer, which allows for rapid and precise measurement of three psychiatric drugs including carbamazepine (CBZ), quetiapine (QTP), and olanzapine (OLZ) in human plasma and whole blood. Quantification is achieved through the use of paper capillary spray combined with miniature mass spectrometry, within the clinically relevant concentration range for three drugs. Only a minimal amount of bodily fluid (50 µl) is required, and the assay turnaround time is less than 2 min. Good linear relationships are established between mass spectrometry (MS)/MS responses and concentration, with correlation coefficients (R2) of no less than 0.99. The limits of detection (LODs) for CBZ, QTP, and OLZ were 0.05 µg/ml, 5 ng/ml, and 5 ng/ml, respectively. Satisfactory precision with relative standard deviations (RSDs) below 21.06% was obtained. Additionally, the developed method was successfully applied to determine the concentrations of psychiatric drugs in real clinical samples. The strengths of this work lie in its portability, speed, and timeliness of detection, which attributed to the characteristics of the miniature MS used, making it suitable for rapid on-site screening.