A new approach to determine salicylic acid in human urine and blood plasma based on negative electrospray ion mobility spectrometry after selective separation using a molecular imprinted polymer.

This paper deals with a method based on negative electrospray ionization ion mobility spectrometry (ESI-IMS) as a detection technique. The method was used to determine the salicylic acid in human urine and plasma after selective separation of salicylic acid (SA) via molecular imprinted polymer (MIP). The ion mobility spectrum of salicylic acid in negative mode and the reduced mobility value for its ion peak is reported in this paper for the first time. In order to combine the technique with negative ESI-IMS, suitable experimental conditions related to MIP (e.g., Soxhlet extraction) were selected. The method was exhaustively validated in terms of sensitivity, imprinting factor, enrichment factor, and sorption capacity. The linear dynamic range of 0.02-2.00 μg mL(-1) and the relative standard deviation (RSD) below 6% were obtained for the analysis of SA through this method. The average recovery was calculated about 92% for the analyzed drug. Finally, human urine and plasma were analyzed and the feasibility of the proposed method was successfully verified by the efficient clean-up of the samples using MIP separation before the analysis by ESI-IMS.