An Undergraduate Experiment: Detection of three Endocrine Disrupting Phthalates DMP, DEP and DBP in Bottled Camel Milk in the UAE

Phthalates or esters of phthalic acid are commonly known for their extensive use as plasticizers to promote the mechanical properties of industrial plastics such as malleability, strength, softness and temperature tolerance. Since phthalates are not chemically attached to the polymers, they can freely migrate from food packages and bottles into fatty food and drinks. Phthalates are proven in several toxicological studies to be of adverse impacts on human health such as respiratory disorders, cardiovascular diseases, neurological problems, birth defects, disruption of endocrine system and different types of cancer. Camel milk is uniquely rich in fats and proteins which may interfere in the analysis of phthalates; thus, a sample preparation step is needed. Therefore, liquid-liquid extraction was performed. An analytical method using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was developed for determinations of three phthalate esters (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP)) in bottled camel milk samples obtained from the local markets in the UAE. Multiple reaction monitoring (MRM) mode was used for mass spectrometry detection on positive chemical ionization (PCI). Calibration curves with very good linearity were obtained for each of the three phthalates after spiking the extracted milk samples with standard concentrations of the three phthalates mixture. The analyzed milk sample was found to contain 57.6 mg.L^-1 of DBP, 0.41 mg.L^-1 of DMP and 0.25 mg.L^-1 of DEP.