Investigation And Risk Assessment Of Bisphenol A In Liquid Food Packaged In Plastic In Jinan City

ObjectivesBisphenol A (BPA) is known as a kind of endocrine disrupters that has a significant influence on the reproduction, development, and other normal endocrine-related life activity. BPA is able to elevate the risk of developing many kinds of diseases, such as diabetes mellitus, hypertension and dysgenesis. In addition, some researches have pointed that the low doses of BPA also have effects on the central nervous system and liver. Currently, BPA is a primary raw material used for the production of polycarbonates (PC), epoxy resins, phenolic resins, polyesters, and polyacrylates. The results of study have indicated that BPA residues were able to be detected in food products stored in packages made of plastic. Plastic containers are widely used in food packaging, which has increased the risk of exposure to BPA. This thesis establishes a practical, efficient, convenient detect method by high performance liquid chromatography- Fluorescence Detector (HPLC-FLD) and Ultra Performance Liquid Chromatography-Mass Spectrometer (UPLC-MS), to detect the contents of BPA in liquid food packaged in plastic in Jinan City and to make risk assessments.Methods1 Determination methods research of BPA1.1 Sample pretreatmentThe liquid foods were extracted by ultrasonic wave device by normal hexane or acetonitrile (ACN), and then liquid-liquid extracted or solid phase extracted. Optimum conditions for Solid Phase Extraction were 5 mL/min as sample flow rate, 2.00 mL methanol/water (40:60, v/v) as washing solvent and 2.00 mL methanol for elution. After the extract liquor was concentrated, the residues were dissolved by methanol, and then determined by instrumental analysis.1.2 HPLC-FLD conditions20 μl of the extract of test samples was injected into a C18 column (250 mm×5 mm,4.6 μm particle size size) and BPA was separated from the mobile phase which is methanol/water (70:30, v/v). The column temperature was held at 25℃ and the retention time for BPA under the described conditions was about 6.24 min, when the flow rate of mobile phase was 1.0 mL/min. The excitation wavelength was 230 nm, and the emission wavelength was 315 nm.1.3 UPLC-MS conditions20 μl of the extract was injected into an UPLC C18 column (50mmx 2.1mm,1.7 μm particle size) and BPA was separated from other compounds using a gradient between mobile phase A (methanol) and mobile phase B (1% ammonium hydroxide). The gradient elution programme was:mobile phase A increased in linear by 5% to 95% within 3 minutes. The column temperature was held at 40℃ and the retention time for BPA under the described conditions was about 2.91 min, when the flow rate of mobile phase was 0.5 mL/min. All the run time was 5 minutes.Negative ion electrospray at-4500 V with 35 psi Curtain Gas,40 psi of ion source Gas 1 and 40 psi of ion source Gas 2 (500℃) were used. BPA was determined using Multiple Reaction Monitoring (MRM).The ion pairs ware 227.100/212.000Da and 227.100/133.000 Da, and their respective declustering potentials were-120V and-110V. There was collision gas regulated to medium pressure at-35eV in the collision cell, when the cell entrance potential was-10 V and the cell exit potential was-8 V. All of above gas was Nitrogen.2 BPA investigation in liquid food packaged in plastic2.1 Sample collectionDifferent kinds of liquid food packaged in plastic including drinking water, beverage, bottled liquor and spices were collected from supermarkets and shops randomly based on the early investigations.2.2 Statistical analysisThe statistical analysis was performed through the SPSS statistics version 20.0 for windows and Excel 2003.The data was presented as mean, maximum, minimum, median, quartile.The used statistical approaches included paired samples t test, Wilcoxon rank-sun test and Spearman rank correlation analysis. The statistical significance was accepted as P<0.05.3 BPA risk assessment in liquid food packaged in plasticThis study adopts Tolerable Daily Intake (TDI) to evaluate the risk of BPA in liquid food packaged in plastic. TDI selected the new BPA safety level 4 μg/kg·bw/d, according to the European Food Safety Authority (EFSA) official website.Results1 BPA determination1.1 BPA determination by HPLC-FLDThe regression equation of BPA was y=169151x+68951 with correlation coefficient 0.9997. In three spiked concentrations, the BPA recovery rate were 98.36%-101.97%. The RSD for intraday were 3.84%-4.32%, and the RSD for interday were 4.12%-4.84%. The limit of BPA determination was 0.5341 μg/L, and the limit of quantity was 2.7314 μg/L.1.2 BPA determination by UPLC-MSThe regression equation of BPA was y=2325.2x+136.98, with the correlation coefficient 0.9998. The recovery rates were 98.27%-101.37%. The RSD for intraday were 3.27%-3.41%, and for interday were 3.51%-3.60%. The limit of determination was 1.16ng/L, and the limit of quantity was 0.9734μg/L.2 Immersion testThe highest transfer volume of BPA came from the Polyvinyl Chloride (PVC) plastic bags. The transfer volume of BPA in Polyethylene Terephthalate (PET) bottle was higher than High Density Polyethylene (HDPE) bottle. There was a positive correlation between the content of ethanol and the content of BPA in soaked solution. In the soaking process, there was a positive correlation between the temperature and the content of BPA in soaked solution, and there was a positive correlation between the time and the content of BPA as well.3 BPA investigation on liquid food packaged in plasticBPA was able to be detected in all kinds of liquid food packaged in plastic. The content of BPA in drinking water and other soft drinks was below the national limit in GB 5749-2006 standars for drinking water puality. Compared to the content of BPA in drinking water packaged in PET bottle, the content of BPA in drinking water packaged in PC bottle was significantly higher (P<0.05).4 BPA risk assessment in liquid food packaged in plasticThe entire TDI (%) of the liquid foods packaged in plastic were low.Conclusions1 The method established to detect the content of BPA in liquid food was sensitive, accurate and reliable.2 The results of immersion test showed that the transfer volume of BPA from plastic containers increased with the increase of both heatingtemperature and the content of ethanol in soaked solution. The lengthy immersion benefited to the release of BPA from plastic containers.3 The BPA pollution of drinking water packaged in PC bottle was more serious than that of mineral water packaged in PET bottle.4 The contents of BPA in drinking water and other soft drinks were lower, and the pollution was not serious.5 The risk of BPA intake by ingesting the liquid food packaged in plastic was low.