Determination of phosphorus in edible oils by inductively coupled plasma-atomic emission spectrometry and oil-in-water emulsion of sample introduction

The determination of phosphorus was carried out using emulsion sample preparation followed by analysis by inductively coupled plasma-atomic emission spectrometry. The optimal oil-in-water (o/w) emulsion and surfactant concentrations were found by applying response surface methodology. Two phosphorus emission lines were tested. Ethoxynonylphenol was a good choice for the emulsion preparation. The optimal concentration for the oil in the o/w emulsion and the surfactant concentrations were ca. 8.0-37% w/w and ca. 1.0-10% w/w ethoxynonylphenol, respectively, for the 213.620 nm line; and an oil phase emulsion concentration between ca. 18-32% w/w and ca. 3-8% w/w ethoxynonylphenol for the 214.911 nm emission line. Good agreement was found between calibration curves for emulsified aqueous standards solutions and o/w emulsions. The use of aqueous standards for calibration purposes is a good addition in the analysis of this type of oil sample where certified standards are not available. Recoveries ranged from 98 to 105% and from 102 to 116% for the 213 and 214 nm lines, respectively with relative standard deviations lower than 7%.