Development of a robust method for the determination of fluorine in liquid petroleum products

Abstract

A robust method for the determination of total fluorine in liquid petroleum products is developed. The methodology is based on the oxidative pyrohydrolytic combustion of the sample, followed by the analysis of the evolved gases absorbed in an absorbing solution by ion chromatography. The detection limit reached for fluorine is 0.5 mg·kg−1 and the quantification limit is 1.4 mg·kg−1, thanks to the optimisation of different variables: combustion variables (temperature and time), sampling loop, and sample weight. The validation process has been developed by calculation of the uncertainty of the measurement and the analysis of spiked samples as there are no certified reference materials. The new methodology set up permits the determination of fluorine over organic materials from the refining industry of different matrices such as fuel oil, acid soluble oil, etc., containing from very low to high fluorine concentrations in a relatively short time, which makes the methodology suitable to be used as a control method. With this methodology, there is no need of sample preparation which implies the no use of acids for that, thus being environmentally friendly.