Isolation of phthalate esters in certain dairy products using solid phase sorbent membrane

Abstract

This study makes an attempt to develop an analytical method to determine dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butylbenzyl phthalate, di-(2-ethylhexyl)phthalate and di-n-octyl phthalate inmilk samples. Eight methods were utilized: namely direct application of solid phase sorbent membrane, dilution of the sample before passing though solid phase sorbent membrane, using the filter aid together with the solid phase sorbent membrane, dilution of the sample prior to the filter aid and solid phase sorbent membrane, extraction sample with solvent before passing through solid phase sorbent membrane, pH adjustment to 2.10 before passing through the solid phase sorbent membrane, centrifugation before passing through the solid phase sorbent membrane, precipitation the sample at pH 4.2 before using solid phase sorbent membrane. The results of the study revealed that the pH adjustment to 2.10 before passing through the solid phase sorbent membrane was the optimum method with percent recoveries ranging from 78.74-129.65 for GC-FID, and 63.95-117.95 for GC-ECD. Percent relative standard deviation (RSD) for GC-FID is in the range of 1.34-5.63, and for GC-ECD 1.18-12.08. The method detection limit (MDL) for GC-FID ranges from 5.25-17.76 µg/kg, and 1.31-17.76 µg/kg for GC-ECD. Best method proposed in this study was applied to the study of six milk samples. Trace amount of DEHP was found in every sample In a range of 10-30 µg/kg.