Simultaneous Determination of 16 Phthalate Esters in Suet Oil by GC-EIMS Coupled with Refrigerant Centrifugation and Ethylenediamine-N-propylsilane Depuration

Phthalic acid esters (PAEs) are endocrine-disrupting chemicals that can enter the human body easily via contaminated food and pharmaceutical excipients. The main challenge in the detection of PAEs in oily samples is not the choice of chromatography-mass spectrometry technology but the pretreatment method. Suet oil (SO), a fatty oil obtained from Capra hircus Linnaeus or Ovis aries Linnaeus, is widely used in food additives and the processing of Chinese medicine. In this paper, refrigerant centrifugation (RC) was optimized to pretreat SO samples for the separation of PAEs and fatty acids. Extraction with acetonitrile (n-hexane saturated) combined with RC (-15 degrees C, 5000 rpm, 15 min, twice) was systematically assessed by four factors (temperature, time, speed, and frequency) according to response surface methodology. Gas chromatography-electron ionization quadrupole mass spectrometry (GC-EIMS) was used as an external standard method for quantification. The correlation coefficients of 16 PAEs were all 0.999 and the lowest quantified level was 0.1 mg kg(-1). The recoveries of the 16 PAEs were 82.9-105.5% with relative standard deviations of 1.5-8.5% (n=6). Compared with solid-phase extraction (SPE), RC had higher recovery rate, lower consumption (economy ratio 65.7%), and powerful sample processing ability. Results showed that the contents of di-n-butyl phthalate (DBP) in two batches of SO were higher than the official limit published by the Ministry of Public Health of China (0.3 mg kg(-1)). This study provides an alternative method for the determination of PAEs in SO and other edible or medicinal animal oil with wide practicability and less matrix interference.