A practical and nontarnishing method for the analysis of trace nickel in hydrogenated cottonseed oil by inductively coupled plasma/mass spectrometry with pressurized PTFE vessel acid digestion

Abstract

A practical and nontarnishing method for the determination of trace nickel (Ni) in hydrogenated cottonseed oil by inductively coupled plasma/mass spectrometry (ICP/MS) was developed. In order to avoid tarnishing in the pretreatment of samples, the technology of pressurized PTFE vessel acid digestion was applied. The temperature and acid content in the digestion were optimized. The results showed that hydrogenated cottonseed oil could be digested completely by the proposed method. Compared with the U.S. Pharmacopeia 28 and British Pharmacopoeia 2003 methods, the developed method avoided the risk of using platinum and the tarnish from silica crucibles. In addition, the analytical cycle of the test solution was shortened by the use of ICP/MS instead of graphite furnace atomic absorption spectrophotometry.