Automated on-line SPE determination of amisulpride in human plasma using LC coupled with restricted-access media column

Abstract

An automated on-line solid-phase extraction (SPE) method coupled with high performance liquid chromatography (HPLC) was developed for the first application to rapid quantification of trace amisulpride in human plasma. A kind of restricted-access media (RAM) column (Capcell Pak MF Ph-1) was adopted for highly efficient extraction of amisulpride and meanwhile for the limited access of macromolecular matrices. It was robust and reusable for >1000 times. The utilization of two programmable pumps enabled the simultaneous execution of SPE and HPLC analysis within 10 min. Additionally, using appropriate valve-switching time was found to efficiently reduce the contamination of HPLC system caused by co-elution of impurity from an RAM column, facilitating continuous analysis of large-scale samples. The method was characterized by free of internal standard (IS), which exhibited low limit of detection (0.0035 μg·mL−1), satisfactory precision and accuracy (recoveries of 98.1%–104.6% with relative standard deviations below 4.6%). Amisulpride was successfully detected in the plasma samples originated from four patients. Notably, interindividual differences of plasma sample matrices did not yield an adverse effect on the accuracy of our IS-free method. The comparison to previous methods shows the superiority of the method in terms of sensitivity, IS requirement, speed, and automation. Thus, the method has great potential for the application to therapeutic drug monitoring as well as large-scale bioanalytical and clinical studies.