Key words: GC-FID; beverage; phthalate
Key words: GC-FID; beverage; PAEs
Summary
A gas chromatographic method for the determination of 16 phthalate esters in beverages was established. Samples were extracted with n-hexane and detected using GC-FID. In the range of 0.10-4.0 mg/L, the linear relationship between the peak area of ​​the target and its mass concentration is good (R 2 >0.99); at the addition level of 0.10 and 0.30 mg/L, the average recovery of sample addition is 92.7-108%. The relative standard deviation (RSD, n=5) is 0.3-5.1%. The method was limited to 50 μg/L of diammonium phthalate. The other 15 compounds were 1.0-5.0 μg/L, and the limit of quantification was 3.0-15 μg/L. The method is sensitive, simple, rapid and accurate. The linear range is wide, which can meet the detection requirements of phthalate esters in beverages.
introduction
Phthalate Acid Esters (PAEs, also known as phthalates), commonly used as plasticizers and softeners in the plastics industry, are used to increase plasticity and plasticity. Resilience and increase the strength of plastics. Since the phthalate plasticizer does not actually polymerize onto the polymer carbon chain of the plastic, the phthalate ester as the main plasticizer is eluted with the use of the plastic product. PAEs are environmental hormones that mimic the natural hormones in the body, interfere with the effects of normal hormones, affect the most basic physiological regulation functions in the body, have carcinogenic, teratogenic and mutagenic effects, and pose a hazard to human health. On June 1, 2011, the Ministry of Health issued a notice stating that phthalate esters were clearly classified as non-edible substances added to the ban and were prohibited from being used in food. Since July 2011, the world's largest plasticizer contaminated beverage event - Taiwan's "clouding agent" storm has attracted attention, the main pollutant is an important member of phthalates.
This paper establishes a method for the determination of phthalate residues in beverages. The method has the advantages of sensitivity, rapidity, accuracy, wide linear range, and the like, and can meet the detection requirements of phthalate esters in beverages. At present, China has promulgated the GB/T 21911-2008 "Determination of Phthalates in Foods" standard test method. The method established in this paper fully meets the requirements of this standard.
Experimental part
Main equipment and reagents
Instrument: Trace 1310 Gas Chromatograph (ThermoFisher) with FID detector.
Reagents: n-hexane, chromatographically pure (ThermoFisher); 16 phthalate standard mixed solutions (O2Si, USA).
Samples: 7 plastic bottled drinks, purchased from supermarkets.
Sample preparation method
Accurately measure 5.0 mL of the sample into a 10 mL glass-filled centrifuge tube, add 1.0 g of NaCl, 2.0 mL of n-hexane, and shake for extraction. After standing, the supernatant is taken for detection.
Sample determination
Instrument conditions are shown in Table 1.
Results and discussion
Method linearity, detection limit and limit of quantitation
A series of mixed standard solutions with concentrations of 0.10, 0.20, 0.40, 0.80, 1.00, 2.00, and 4.00 mg/L were prepared and injected sequentially from low to high concentrations, and linear regression was performed with mass concentration and peak area as standard curves. The results showed that 15 phthalate esters had a good linear relationship in the range of 0.10~4.00 mg/L. The DNP response is poor and the linear range is 0.40 to 4.00 mg/L. Using the method of adding the target compound to the sample, the detection limit is calculated according to the characteristic ion mass chromatographic peak signal-to-noise ratio R S/N = 3, and the quantitative limit of R S/N = 10 is calculated. The results are shown in Table 3.
Determination of method precision and recovery
A 5.0 mL sample of the beverage was weighed and two standard concentrations of the standard were added, and each concentration level was measured in parallel five times. The results showed that the average recovery was 92.7-108%, and the relative standard deviation (RSD, n=5) was 0.3-5.1%. The recovery and precision data results are shown in Table 4.
Determination of phthalate esters in 7 samples of commercially available beverages
The residual amount of phthalate esters in seven plastic bottled beverage samples was measured according to the above pretreatment method. The measurement results are shown in Table 5. The standard and sample addition spectra are shown in Figure 1.
in conclusion
The method adopts the technique of n-hexane extraction and gas chromatography to establish an analytical method for 16 kinds of phthalate residues in various beverages. At the two addition levels of 0.1 and 0.3 mg/L, the recovery was 92.7-108%, and the relative standard deviation (RSD, n=5) was 0.3-5.1%. The method detection limit was determined by didecyl phthalate. Outside of 50 μg/L, the remaining 15 compounds ranged from 1.0 to 5.0 μg/L with a limit of quantitation of 3.0 to 15 μg/L. The method has the advantages of sensitivity, simplicity, accuracy, and wide linear range, and can meet the detection requirements of phthalate esters in various types of beverages.
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