Selective Method Based on Negative Electrospray Ionization Ion Mobility Spectrometry for Direct Analysis of Salivary Thiocyanate

摘要

This study describes a novel technique for direct analysisnof thiocyanate in human saliva using negative electrosprayionnmobility spectrometry (ESI-IMS) and without anynconsiderable sample pretreatment. The ESI-IMS systemnwith nearly complete desolvation cannot be useful fornsalivary thiocyanate analysis because complete overlappingnoccurs between the format peak of the solvent andnthe thiocyanate peak. In addition, the chloride ionsnexisting in saliva produce a very broad peak, which has andrastically interfering effect on SCN- determination. Innthis study, with a little change in the operation conditionsnof the apparatus (lowering the flow rate of the driftngas), it was possible to overcome these problems. Thendesolvation process was decreased in the lower flownof drift gas, and this caused the SCN- peak to benseparated completely from other interference peaksnsuch as chloride ions. The results obtained in thisnproposed methodology provide the detection limit ofn0.003 μg/mL and the linear dynamic range from 0.01nto 1.00 μg/mL for the thiocyanate. Several humannsaliva samples were analyzed with the proposed negativenESI-IMS, and the satisfactory results confirm thencapability of the method for direct analysis of salivarynthiocyanate.