DETERMINATION OF BISPHENOL A IN PLASTIC PACKAGING BY USING THE METHOD OF LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY
Tran Hai Dang1, O.B. Rudakov2, E.A. Khorokhordina2, E.S. Logvina2
1University of Agriculture and Forestry - TNU
2Voronezh State Technical University
ABSTRACT
Many studies confirming the toxicity and hazard of bisphenol A to human health have been conducted so far. It should be noted that in the EU, the established specific migration limit for bisphenol A is 0.6 mg/kg for the materials based on plastics contacting with food. The research objects were 6 samples of plastic packaging widely used in Vietnam, whose materials could contain “free” BPA. In the research, the technique of liquid chromatographic-mass spectrometric determination of “free” bisphenol A in plastic packaging was developed. In order to extract bisphenol A, the method of liquid extraction from a material with the help of the mixture of acetonitrile - ethyl acetate (85:15) was proposed. The results of the detection of bisphenol A free in packaging widely used in Vietnam were discussed.
Keywords: Bisphenol A, toxic, liquid extraction, HPLC-MS/MS, plastic packaging
Received: 11/12/2018; Revised: 22/12/2018; Approved: 28/12/2018
XÁC ĐỊNH BISPHENOL A TRONG CÁC HỘP NHỰA BẰNG PHƯƠNG SẮC KÝ LỎNG KHỐI PHỔ
Trần Hải Đăng1, Rudakov O. B.2, Khorokhordina E. A.2, Logvina E. S.2
1Trường Đại học Nông Lâm - ĐH Thái Nguyên
2Trường ĐH tổng hợp kỹ thuật Voronezh, LB Nga
TÓM TẮT
Cho đến nay có nhiều nghiên cứu đã được tiến hành để xác nhận độc tính và nguy cơ của bisphenol A đối với sức khỏe con người. Tại EU giới hạn của bisphenol A là 0,6 mg/kg đối với các vật liệu nhựa tiếp xúc thực phẩm. Đối tượng trong nghiên cứu này là 6 mẫu hộp nhựa dùng đựng thực phẩm được sử dụng rộng rãi tại Việt Nam, các vật liệu này có thể chứa bisphenol A tự do. Trong nghiên cứu đã phát triển kỹ thuật xác định bisphenol A tự do trong các hộp nhựa bằng phương pháp sắc ký lỏng khối phổ. Để chiết xuất được bisphenol A, nhóm tác giả đã sử dụng hỗn hợp dung môi trơ acetonitril - ethyl acetate (85:15). Kết quả đã phát hiện bisphenol A tự do trong các hộp nhựa dùng đựng thực phẩm được sử dụng rộng rãi ở Việt Nam.
Từ khóa: Bisphenol A, chất độc, chiết xuất lỏng, HPLC-MS/MS, hộp nḥa.
Ngày nhận bài: 11/12/2018; Hoàn thiện: 22/12/2018; Duyệt dăng: 28/12/2018
Introduction
Nowadays polymer materials are widely used in almost all industry sectors in Vietnam and Russia. More often than not, these materials for technical and domestic purposes are made of inexpensive polymers, in which the content of harmful substances such as monomers, plasticisers and antioxidants can exceed concentrations safe for human health.
Therefore, the analytical control of ecotoxicants in these materials has become a pressing problem which should be tackled.
For instance, epoxy resins derived from BPA are applied as a coating on the interior surface of beverage and food cans. “Free” BPA can be present in polycarbonate plastics. It should be noted that a wide variety of products such as water and drink bottles, sports equipment, medical instruments, dental fillings and sealants, eyeglass lenses and household appliances are made of these plastics. BPA is not only used as a monomer but also as an antioxidant in some plasticisers and polymerisation inhibitor of polyvinyl chloride [1], [5], [9].
Many studies confirming the toxicity and hazard of BPA to human health have been conducted so far [2], [3], [6], [7], [11], [12].
As a synthetic analogue of oestrogen, BPA, which is an endocrine disruptor, easily disturbs hormonal balance. It causes fertility decline, breast cancer, obesity, precocious puberty and diabetes, adversely affects the central nervous system and shows embryotoxicity. It should be noted that in the EU, the established specific migration limit for BPA is 0.6 mg/kg for the materials based on plastics contacting with food [10].
As part of international cooperation, the scientists of the department of Chemistry and Chemical Technology of Materials of
Voronezh State Technical University and lecturer of the department of Science and Technology of Thai Nguyen University of Agriculture and Forestry have developed extraction-chromatographic methodology of
“free” bisphenol A (BPA) determination with the help of HPLC-MS/MS in plastic materials.
Experimental part
The research objects were 6 samples of plastic packaging widely used in Vietnam, whose materials could contain “free” BPA.
The sample of the material was being ground until it reached the size 5×5 mm and then the sample mass of ~ 0.5 g was weighed on the analytical balances. The sample weight was put into a conical flat-bottom flask, 10 sm3 of acetonitrile - ethyl acetate mixture (85:15) was added to it, and the flask was shaken by using a vibromixer for 15 minutes. Then the analysis was conducted with the help of HPLC-MS/MS method (Fig. 1) on a liquid chromatograph Shimadzu consisting of two high pressure pumps LC-20AD XR with the automatic sample injection system SIL-20AC XR, column InertSustain С18 (granulation was 5 μm, length was 150 mm, diameter was 4.6 mm) (Japan). The volume of the injected sample was 10 μl. The mass spectrometer was MS/MS ABSciex 5500 QQQ. The ionisation source was ESI, the regime of negative ions, spray voltage was 4 kV. The nozzle temperature (IS) was 400 oC. The mobile phase was acetonitrile – water, gradient (Table 1).
The sample preparation and analysis were conducted by using the equipment given by the Laboratory of Food Chemistry and Toxicology National Institute for Food Control in Hanoi, Vietnam.
Fig. 1. Chromatogram of bisphenol A solution in the extraction agent, С=10 ng/ml.
Table 1. The gradient of the mobile phase HPLC-MS/MS
Time, min Water, vol.% Acetonitrile, vol. % Speed, ml/min
0.01 90 10 0.6
1.00 90 10 0.6
4.00 0 100 0.6
7.00 0 100 0.6
7.50 90 10 0.6
10.00 90 10 0.6
Fig. 2. Calibration for the determination of BPA in the extraction agent Results and discussion
The mixture of acetonitrile - ethyl acetate (85:15) was chosen as an extraction agent because it is better at solving BPA and extracting this analyte from plastic materials (Acetonitrile and ethyl acetate from Germany). Furthermore, it is both less
stressed that the addition of 15% of ethyl acetate to acetonitrile increases the degree of the extraction of hydrophobic phenols, to which BPA belongs, up to 98.5%. The coefficient of the distribution of hydrophobic phenols between the water and acetonitrile - ethyl acetate mixture (85:15) rises enormously with inorganic salts or when
temperature lower than -10 oC, this mixture as well as pure acetonitrile is capable of separating from water, which makes it suitable for use not only at room temperature but also under the conditions of low- temperature liquid-liquid extraction.
Consequently, it is possible to apply this mixture to the process of BPA identification both in plastic packaging items and products which are wrapped in them. In order to plot a calibration curve, BPA was gradually dissolved in the acetonitrile - ethyl acetate solution (85:15) with the concentrations of 20, 50, 100, 200 ng/ml respectively (Fig. 2).
Fig. 2 shows the calibration curve. The degree of correlation R=0,9988.
The analysis of 6 real samples of typical plastic packaging widely used in Vietnam showed the significant content of BPA in the samples №3 and №6 (Table 2). The chromatograms for certain samples are presented in Figures 3 and 4.
Thus, the samples in which the specific migration level of BPA from the material was exceeded should be considered as a serious health hazard. Its content in other samples was lower than the dangerous level.
Fig. 3. Chromatogram of the baby bottle “Zoo” HT04T0414, Vietnam
Fig 4. Chromatogram of the box “Pioneer” PN3165L/2C-P3, Thailand.
Table 2. The results of the materials analysis
Sample number Model name Bisphenol A concentration (mg/kg)
1 Cup “Viet-Nhat”№ 01, Vietnam Traces
2 Food packet “Freshness” BC0175, Vietnam Traces
3 Baby bottle “Farlin” TOP 848, Taiwan 5.5
4 Box “Pioneer” PN3165L/2C-P3, Thailand Traces
5 Box “Minh Cau” № 64988, Vietnam Traces*
6 Baby bottle “Zoo” HT04T0414, Vietnam 10.2
*Traces: lower C=0.05 mg/kg) Therefore, the results of the sample
preparation, which was done taking into account the conditions of the methodology of BPA determination by HPLC-MS/MS make it possible to come to the conclusion that the control of this contaminant content in plastic packaging for food and drink is an urgent task. The developed extraction- chromatographic method of BPA determination in polymer materials is an effective and promising way of identifying BPA not only in plastic packaging but also in food into which it migrates from plastics.
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