A rapid and sensitive method for the determination of inorganic chloride in oil samples

A novel isotope dilution method for the analysis of inorganic chloride in fuel oil matrix is presented. The samples were diluted by isopropyl alcohol:toluene, mixed with Cl-37(-) internal standard and reacted with triethyloxonium tetrafluoroborate at room temperature. This reagent promoted conversion of Cl- into stable ethyl chloride (EtCI) which was selectively detected by headspace GC-MS/MS with no matrix effects. A limit of detection of 0.2 mg kg(-1) Cl- was obtained in fuel oil. The method was tested on the NIST SRM 1634c (trace elements in residual fuel oil) and validated through a series of robustness tests. Over 18 days, the variation in the signal response was less than 10% and the RSD for quantitative isotope dilution results was below 3%. Overall, the method is fast, simple and allows robust quantitation of inorganic chloride directly in the non-aqueous media. (C) Copyright 2019 Published by Elsevier B.V. All rights reserved.