Research On Analytical Method Of Phthalates In Vegetables

Vegetables as essential food contain many nutrients for example protein, minerals, vitamins which are necessary for human.90%of vitamin C and60%vitamin A in body come from vegetables. With the development of industrialization and the progress of scientific, the production and economic benefits of vegetables were increased. The security of vegetables attracted people’s attention, simultaneously. The strict rules of pesticide residues in vegetables were formulated in home and abroad. While, there was no provision of environment hormones in vegetables.Phthalates as an important EDCs are widely distributed in environment and exposed to soil, air, water and body. Phthalate diesters could be degraded into phthalate monoesters by biotic or abiotic, which may interfere with endocrine system and cause teratogenic, cancer and mutation. Because of the widespread use of plastic greenhouse, it is very likely to produce phthalates residues in vegetables. Therefore, improving the quality and ensuring the safety of vegetables become a serious problem. QuEChERS is a new pretreatment method which frequently used in fruits and vegetables. Compared with traditional sample preparation method, QuEChERS has a lot of advantages such as high sample throughput, low dosage of solvent and no chlorinated solvents. In this paper, the conditions of extraction, enrichment, purification and detection were researched. The methods of QuEChERS-HPLC for analyzing phthalate diesters and monoesters and QuEChERS-GC/MS/MS for19phthalates in vegetables were established. The results are as follows:(1) The QuEChERS pretreatment conditions for extracting phthalates in milk were built. We optimized the conditions of extraction and purification in the experiment. The best extraction conditions were:ultrasonic extraction at15min with acetonitrile (0.05%acetic acid),4g MgSC4and1g NaCl, centrifugal speed of3500rpm. The optimal purification conditions were:50mg of C18, injection solvent of acetonitrile.(2) Combined with UVD-high performance liquid chromatography, we optimized chromatographic conditions. Reversed phase column used COSMOSIL5C18-AR-Ⅱ (4.6mm×150mm,5μm), mobile phase were consist of water (B)(0.1%acetic acid) and acetonitrile (0.1%acetic acid)(A), detection wavelength set at228nm. The program of binary high-pressure gradient elution set as:0min,40%B;20min,90%B;20.01-35min,90%B;36-40min,40%B. The flow rate was1mL/min, and column temperature was30℃Under the proposed chromatographic conditions, the seven phthalates in the vegetable could separate well, each phthalates standards in the range of0.1-5mg/kg had a good linear relationship, and the LODs were9.55-26.81μg/kg. In order to validate the optimized method, three different spiked levels (0.1,0.2,1mg/kg) with three replicates were implemented. The recoveries were72.4-108.9% with relative standard deviations of0.9to5.6%, which demonstrated that the experimental results were precise and accurate.(3) Combined with gas chromatography-triple quadrupole mass spectrometry, we improved chromatographic and mass spectrometry conditions. Under the mode of El, the column of HP-5ms (30m×0.25mmx0.25μm) was used. The temperature was:60℃hold1.5min; at20℃/min to220℃, hold1min; at5℃/min to280℃, hold4min. The carrier gas was helium; collision gas was nitrogen. Injection volume was1μL Injection port temperature was280℃. MMI inlet with splitless was used.(4) The proposed method was used to detect phthalates in vegetable.