Abstract
1. Abstract
Metal food cans are commonly coated with epoxy films made from phenolic polymers
produced from bisphenol A (BPA). BPA can migrate from can coating to contaminate
canned food. Therefore, this study was carried out to determine the concentration of
BPA both in can coatings and canned food. The method of analysis BPA was based
on solvent extraction and concentration followed by Liquid Chromatography/ Tandem
Mass Spectrometry using BPA-d16 as internal standard. The limit of detection in can
coating and canned food are 0.01 µg/dm2 and 0.2 µg /kg respectively. Fourty five
cans used for this study were coated with 3 different coatings which were epoxy
phenolic, PVC organosal laminated with polyester (PS) and PVC organosal
laminated with polyethylene terephthalate (PET). The results shown that the
concentration of BPA in can coated with epoxy phenolic were 0.2-9.30 µg/dm2 while
the concentration of BPA in cans coated with PVC organosal laminated with PS or
PET were ranged from not detected to 1.43 µg/dm2. The BPA was detected in 37
canned foods. The concentrations of BPA in canned tuna in oil packed in …………
epoxy phenolicwere 46.1-51.1 µg/kg. However, the concentration of BPA in 5
samples of canned tuna, sardine and chicken in jelly were 13.3 - 14.3 µg /kg. This
study was shown that BPA can migrate into oily food more than aqueous food.
2. Introduction
Bisphenol A is an organic compound used extensively in the manufacture of
consumer products, such as polycarbonate (PC) baby bottles, epoxy-resin can liners,
food containers and utensils, dental sealants, protective coatings, flame-retardants,
and water supply pipes, which leads to a widespread human exposure to BPA. Trace
amount of BPA have been detected in water and food products kept in PC containers.
The BPA or Bisphenol A (Figure 1 ) has become well known over the past ten years
as its effects on human health and well being have been raised . The concerns over
BPA began with polycarbonate baby bottles and spread to include other types of
bottles. Several risk assessment studies have been performed over the last 10 years by
different regulatory bodies in Europe, USA, Japan and Canada. The results shown that
BPA is an endocrine disruptor. It has the ability to bind to the nuclear estrogen
receptor and exert weak estrogenic effects, therefore, their presence and
concentrations in food products must be monitored.
Therefore, several can manufacturer have developed various types of plastic which
can be use for lining in metal can instead of BPA liner or as and overlay on an epoxy
undercoating, which reduces reaching capability of BPA up to 95% into food and
beverages
The present paper gives data obtained by analyzing bisphenol A in can with three
difference coatings and 37 canned food.
3. Experimental
3.1 Chemicals. HPLC -Grade acetonitrile ,methanol , water were purchased by
Labscan were used.The internal standards were d16-BPA (98 atom % D, fully
labeled) and Bisphenol A (BPA,purity 99% ) were purchased from Sigma-Aldrich .
All standard were stored at-20C. sodium sulfate เกรดอะไร
3.2 Standard and stock solution
Standard solution of BPA Stock solutions of standard BPA containing 1,000 mg/L
and intermediate standards solution of 0.002mg/L of BPA were prepared in
acetonitrile .
Standard solution of d-16 BPA The standard d-16 BPA containing 1,000 mg/L and
were prepared in acetonitrile .store at 4C for three months and intermediate d-16
BPA of 0.001mg/L of BPA were prepared in acetonitrile
3.3 The calibration curves
The calibration curves were obtained by dissolving appropriate amount of 0.002mg/L
of BPA stock solution into six concentration, that are 10,20,50,100,200,and 400
ng/Ml.The calibration curve were plotted between the concentration of BPA and the
ratio of the area of chromatogram BPA m/z 227/212 and BPA d16 241/223
3.4 LC-MS-MS analysis
Identification and quantification of analyze were carry out using the LC tandem
mass spectrophotometry (6410 Agilent Technologies) . A symmetry of C18
column (Zoebax Eclipse XDB- 50 mm x 4.6 mmi.d.,1.8 µm ) was used for LC
separation. The column oven was 35 C. The flow rate was 0.3 ml/min. and the
injection volume was 10 µg/l. Ammonium acetate 2 mM and methanol (40:60)
were used as mobile phase. The mass spectrometer was operated in negative mode
in multiple-reaction monitoring (MRM mode). The chamber current was maintain
at 0.1 uA. The nebulizer, desolvation ………. was supplied with nitrogen. The
nebulizer were set as 10L/min and were held at 300C.
3.5 Sample collection and preparation
Can: forty-five cans used for this study were coated with 3 difference coatings which
were epoxy phenolic, PVC organosal laminated with polyester and PVC organosal
laminated with polyethylene terephthalate. Empty cans were washing with distilled
water and dry at room temperature. Acetonitrile were used to extract BPA form the
lining at room temperature for 24 hrs. The extracted solutions were stored in volume
metric flasks
Canned food: The food from each samples were homogenized by blender and
transfer 5 g. into conical flask 250 ml., added sodium sulfate 10 g. then added 400 µl.
of internal standard (BPA-d16 0.001 mg/ml) and 50 ml. acetonitrile. The solution
were shaken as 190 rpm for 20 min. The extracted were filtered by filter paper and
extracted for a second time with 50 ml. acetonitrile, shaken for 20 min, filtered the
extracted (ACN phase ใช่ป่าว) again. Concentrate the ACN phase by vacuum evaporator
until dry add acetonitrile for 2 ml. and add 5 ml for normal hexane and shaken the
solution. Transfer the solution to the centrifuge tube and centrifuged at 3500 rpm for 5
min, pipette the acetonitrile layer. Add 3 ml. of hexane into the acetonitrile layer
shake and centrifuged 3500 rpm for 5 min. Transfer the solution into centrifuge tube
(หลอดก้ นแหลม). Transfer the 1 ml solution into 5 ml. test tube, pipette 1 ml. acetonitrile
solution (acetonitrile: water = 35:65) into the test tube mix and leave the solution for 3
min. the solution was filter and transfer to (หลอดแก็บ ตย) for analyzing by LC-MS-MS
มี ODS guard column. ไหม
4. Result and discussion.
Analytical characteristic ,i.e. Repeatability, LOD, LOQ and linearity were
summarized in Table 1
4.1 Bisphenol A leaching from metal can
table 1
Performance
result
characteristic
Repeatability
RSD = 7.46%
5.38% (n=10)
4.71% (n=10)
(n=10) at BPA
at BPA 400
at BPA 800
0.8 ng/g
ng/g
ng/g
Linearity
R2 ≥0.995
LOD
0.07 µg/dm2
(0.4 ug/g)
LOQ
0.13 µg/dm2
(0.8 ug/g)
recovery
83-101%
Range
0.8-800 µg/kg
uncertianty
1.78
3.56 ng/g
ใส่ กราฟ ใส่ โครมาโตรแกรม
4.2 Bisphenol A leaching from canned food
Table 2
Performance
result
characteristic
Repeatability
RSD = 7.46%
5.38% (n=10)
4.71% (n=10)
(n=10) at BPA
at BPA 400
at BPA 800
0.8 ng/g
ng/g
ng/g
Linearity
R2 ≥0.995
LOD
0.07 µg/dm2
(0.4 ug/g)
LOQ
0.13 µg/dm2
(0.8 ug/g)
recovery
83-101%
Range
0.8-800 µg/kg
uncertianty
1.78
3.56 ng/g
Table 2 gives the summarises performance characteristics of the optimimised LC/MSMS method.Ther value of RSD are which indicate good repeatability
5. Conclusion.
The concentration of BPA leaching form canned coated with epoxy phenolic were
9.30 µg/dm2 (the migration limit = 10 µg/dm2)while the concentration of BPA can
not detected and found in very low concentration (…เท่าไหร่) when can coating with
polyester or polyethylene terephthalate as well as BPA concentration from such cans
using for canned food were found in food at very low concentration too. Canned
tuna in oil had the highest BPA level with the average and maximum BPA level in
can tuna in oil 61.01 and 65.15, respectively. were while BPA concentration.
แนวทางเขียนบทสรุ ป
In this study, the concentration of BPA content from 45 cans coated with 3 different
coating materials and from 37 canned foods was investigated. In case of cans coated
with different polymers, it was found that cans coated with epoxy phenolic has the
highest leaching content of BPA which is equal to 9.30 µg/dm2 (the migration limit =
10 µg/dm2). This is not surprising because BPA is used as a starting substance to
make epoxy resin……(เติมข้อมูลเพื่อสนับสนุนว่าทาไม epoxy phenolic ถึงมี BPA
ออกมามากสุด) For the study of BPA migration from canned food, the results shown
that canned food in oil has higher BPA content than that in water; for example,
canned tuna in oil had higher BPA concentration than canned tuna in water.
Therefore, this study shows that BPA can migrate into oily food more than aqueous
food.
ข้อสังเกต:
บทความนี้อ่านแล้วเป็ นงานที่น่าสนใจ แต่ไม่ค่อยเข้าใจส่ วนของการหา BPA ในอาหารกระป๋ อง
เพราะไม่ได้ให้รายละเอียดว่าเป็ นอาหารกระป๋ องที่ตวั กระป๋ องเคลือบด้วยสารอะไร (เป็ น epoxy phenolic
ที่ให้ BPA ออกมาได้มากสุ ดหรื อไม่) และ 37 ตัวอย่างเป็ นอาหารอะไรบ้าง?
ได้จดั กลุ่มเพื่อเปรี ยบเทียบระหว่างอาหารในน้ ามันกับน้ ามากกว่าทูน่าหรื อไม่
เพื่อเป็ นข้อมูลสนับสนุนที่มากขึ้น