Analytical Methods for Determination of Bisphenol A

CAS no.
80-05-7
Organic compound
Bisphenol A (2,2-bis-(4hydroxyphenyl)propane)
Chemical structure
A195157_1_En_2_Fig3_HTML.gif
Formula
C15H16O2
Molecular weight
228.29 g/mol
Boiling point
398 °C at 760 mmHg
Melting point
153–157 °C
pKa
9.6–11.3
Water solubility
120–300 mg/L
Vapor pressure
0.2 mmHg at 170 °C
Log Kow
2.20–3.82
Henry’s constant
1.0 × 10−10 atm m3/mol
Bisphenol A is a chemical manufactured in large quantities. It is estimated that 1,150 tonnes/year are produced and used in Western Europe. Almost 96 % of BPA is used as a monomer for the production of polycarbonate and epoxy resins. Other applications include its use as stabilizing agent in plastics, as antioxidant in tire production, and as basic chemical in the production of certain flame retardants. The BPA-based materials are used in food and beverage containers, protective coating, automotive lenses, optical lenses, adhesives, powder paints, building materials, compact disks, thermal paper, paper coatings, dental, surgical, and prosthetical materials [3, 4]. The production and extensive use of these materials result in the release of this compound into the environment during processing, handling, and transportation of final products. It was estimated that 39.5 % of the total environmental release of BPA comprised total air release, 1 % water release, 54 % land release, and 5.4 % underground injection [3].
Various in vitro and in vivo assays showed that BPA presents estrogenic activity, and consequently, it is considered as important organic pollutant [3]. BPA may cause a variety of adverse effects on reproduction and development of exposed organisms, being more striking and irreversible during embryonic development. These effects may occur even at doses of BPA well below those showing adverse effects in routine toxicity studies [37].
The US-EPA, under the Toxic Substances Control Act, indents to consider initiating rulemaking to identify BPA on the Concern List as a substance that may present an unreasonable risk to the environment on the basis of its potential for long-term adverse effects on growth, reproduction, and development in aquatic species at concentrations similar to those found in the environment [4]. BPA is candidate to be among the first substances to go through Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) in EU registration (EU Regulation No 1907/2006). Canada was the first country that has classified BPA as toxic substance and announced restriction of imports, sales, and advertising of polycarbonate baby bottles containing BPA. Recently, the European Commission published a new directive (2011/8/EU) to restrict bisphenol A in feeding bottles that are intended for use by infants under the age of 12 months [8]. According to this directive, member states are required to prohibit the manufacture of polycarbonate feeding bottles containing BPA as well as their import and sale in EU.
The study of the occurrence of BPA in various environmental compartments, in food, in dental materials, and in biological fluids contributes to the knowledge on the environmental fate of this compound, the possible pathways of exposure, the biotransformation mechanisms, and the possible risks. In order to identify and determine trace levels of BPA in complex matrices, sensitive analytical methods are required.
A number of analytical methods have been developed for the determination of BPA. The general scheme of analysis usually comprises isolation from samples through extraction, cleanup steps, and determination by employing a sensitive analytical technique. The major problems associated with the analysis are possible loss or contamination during sampling and storage, the need of preconcentration and, possibly, of cleanup, as well as the need for highly efficient separation procedures and selective detection techniques. Reliable analytical procedures require detailed method validation and careful evaluation. In addition, sampling and sample preparation should be considered integrally with the characterization of an analytical procedure.

2.2 Sampling and Storage

The first step in the measurement of BPA involves representative sampling and maintaining sample integrity prior to analysis. The sampling strategy should reflect the known or expected variability of the system.
All the equipment that may come into contact with sample or the extract should be free from interfering compounds. The sampling containers should be made of materials that do not change the sample during the contact time. Plastics and other organic materials should be avoided during sampling, sample storage, or extraction. Glass brown bottles with glass stoppers or with PTFE-lined screw caps, carefully precleaned, are recommended for sampling and storage of samples. Rinsing with acetone is recommended for all glassware used in the analysis. Alternatively, non-volumetric glassware may be heated to at least 200 °C for a minimum of 2 h. The samples should be analyzed as soon as possible; otherwise, they can be stored at 2–5 °C for 2 weeks [9].

2.3 Extraction Techniques

Sample preparation is an important stage in the analytical process when trace analyte determination is needed. The analysis of pollutants at low concentrations in complex matrices requires the elimination of interferences and the reduction of final extract volumes to attain higher preconcentration of target analytes. Generally these pretreatment methods are necessary in order to improve the detection and quantification limits, avoid matrix implications, limit background noise, and extend the life of the analytical column.
The analysis of BPA in environmental, food, and biological liquid samples employs a wide range of sample extraction techniques. Solid-phase extraction is frequently used for isolation and preconcentration of BPA (Tables 2.2, 2.3, 2.4, and 2.5). Moreover, other techniques such as the traditional liquid–liquid extraction, solid-phase microextraction, and stir bar sorptive extraction have been used.

Table 2.2

Analytical methods and concentration range of BPA in dental materials
Dental materials
Samples analyzed/pretreatment
Analytical method
LOD
Concentrations of BPA
Reference
Core build-up materials
Eluates in ethanol 75 %
LC-MS/MS
0.5 μg/mL
BDL-6.14 μg/mL
Brenn-Struckhofova and Cichna-Markl [43]
Column: CC 125/4 Nucleodur 100-5 C18
Mobile phase: 0.1 % formic acid/acetonitrile
Diagnostic ions: m/z 227
Orthodontic adhesives
Eluates in alcohol 99 %
HPLC-UV/Vis
0.1 ppm
BDL
Fontana et al. [57]
Column: C18
Mobile phase: acetonitrile/water (60:40 v/v)
Wavelength: 228 nm
Dental sealants
Eluates in ethanol 95 %
HPLC-UV
0.0001 μg/mg
BDL
Cunha et al. [58]
Column: Nova Pak C18
Mobile phase: A acetonitrile/water (50:50 v/v)
B acetonitrile
Wavelength: 215 nm
Dental sealants
Eluates in distilled water
HPLC-UV/Vis
BDL
Salafranca et al. [59]
Column: C18 resolved column
Mobile phase: isocratic 70 % methanol
Wavelength: 215 nm
Orthodontic adhesives
Eluates in distilled water
GC-MS, EI, SIM
2.3 ng/L
0.16–2.90 μg/L
Maragou et al. [44]
SPE (Oasis HLB)
Elution with acetone
Derivatization with BSTFA
Column: 5 % diphenyl-95 % dimethyl polysiloxane
Diagnostic ions: m/z 357.2, 358.2
Internal standard BPA-d16
Composites/sealants
Vigorous agitation with distilled water (37 °C) at various pH values (1–12)
HPLC-UV
0.20 μg/mL
0.3–116.1 μg/mL in polymerized materials
[60]
Column: C18
Mobile phase: gradient A acetonitrile/water (1:1 v/v) and B acetonitrile
<0.2–179.5 μg/mL in unpolymerized materials
Wavelength: 280 nm
GC-MS
Column methyl silica
Diagnostic ions: m/z 213, 228
Dental sealants/adhesive resins
Eluates in water/acetonitrile (43/57)
HPLC-UV/Vis
100 pg
BDL
[60]
Reversed phase column
Mobile phase: water/acetonitrile (43/57)
Wavelength: 215 nm
GC-MS
Column: methyl silicon DB-1
Dental sealants
Saliva
GC-MD, NCI
0.1 ng/mL
0.17–96.2 ng/mL
Kawaguchi et al. [46]
Urine
Column: 5 % phenyl-methyl-polysiloxane
0.6–112.2 ng/m
SPE C18
Diagnostic ions: m/z 407, 299
Internal standard 13C12-BPA
Elution with methanol
Derivatization: pentafluoro-benzyl bromide
Composite resins
Saliva
ELISA “EIKEN”kit
 
0.3–100 ng/L
Shao et al. [39]
Dental sealants
Saline solution (37 °C)
HPLC-FLD
5 ppb
BDL
Chang et al. [45]
Saliva
Column: Supelcosil LC-C18
BDL
Serum
SPE C18
Elution with acetonitrile
Mobile phase: acetonitrile/water (50:50 v/v)
Exc/Emis wv: 278/315 nm
Restorative composites
Eluates in ethanol
HPLC-diode array
 
BDL-84.4 μg/100 mg 3.5–30 μg/mL
Kawaguchi et al. [61]
Dental sealants
Saliva
Column: S5 ODS
Mobile phase: gradient A acetonitrile/water (1:1) and B acetonitrile
Wavelength: 235 nm
GC-MS confirmation
BDL below detection limit
Table 2.3

Analytical methods and levels of BPA in environmental samples
Samples/Country
Pretreatment
Analytical method
LOD
Concentration of BPA
Reference
River water
LLE with dichloromethane
GC-MS, EI, SIM
0.5 pg/μL
17–776 ng/L
Heemken et al. [21]
Column: 5 % phenylmethyl silicon
BDL-249 ng/L
Sea water
Diagnostic ions: m/z 315, 331, 407
HPLC clean up
Internal standard BPA-d16
Germany
Derivatization with HFBA
Freshwater
Filtration
GC-MS, EI, Full-scan
20 ng/L
BDL-1, 924 ng/L
Quednow and Püttmann [22]
Column: BP-X5
SPE (Bod Elute OOL)
Diagnostic ions: m/z 213, 228
Germany
Elution with methanol/acetonitrile
Surface waters
SPE (LiChrolut)
GC-MS/MS, EI
0.1 ng/L
0.5–410 ng/L
Fromme et al. [23]
RP-HPLC-FLD (Exc/Emis wv 228/310 nm)
18–702 ng/L
2.0 ng/L
Sewage effluents
Elution with acetone
Mobile phase: gradient A hexane
Germany
B hexane/methanol/isopropanol (40/45/15)
Surface waters
Filtration
GC-MS, EI, SIM
2.4 ng/L
9–76 ng/L
Voutsa et al. [24]
Column: DB-5
Diagnostic ions: m/z 357.2, 358.3
SPE (Oasis HLB)
Internal standard BPA-d16
Elution with acetone
Switzerland
Derivatization with MSTFA/2 % Sylon BTZ
Surface water
Filtration
LC-MS/MS, ESI, NI, MRM
1.1 ng/L
2–46 ng/L
Jonkers et al. [25]
1.3–1, 640 ng/L
Column: 100 RP18ec
Mobile phase: gradient A water 4 mM ammonium acetate B methanol
Wastewaters
SPE (Oasis HLB)
Precursor ion: m/z 227.02
Product ion: m/z 211.8
Internal standard BPA-d16
Switzerland
Elution with MTBE/2-propanol
Wastewaters
SPE (Oasis HLB)
GC-MS, EI, SIM
0.5 ng/L
450 ng/L
Jeannot et al. [26]
Column 95 % dimethyl-5 % phenylpolysiloxane
Elution with methanol-diethyl ether (10:90 v/v)
Identification ion: m/z 358
GC-MS/MS, EI
Precursor ion: m/z 358
Product ions: m/z 191, 267, 357
France
Derivatization with BSTFA
Surface waters
Filtration
GC-MS, EI, SIM
2.3 ng/L
15–460 ng/L
Arditsoglou and Voutsa [27, 28]
SPE (Oasis HLB)
Column: 5 % diphenyl-95 % dimethyl polysiloxane
Pothitou and Voutsa [29]
15–56 ng/L
Arditsoglou and Voutsa [30]
15–2, 358 ng/L
Elution with acetone
Diagnostic ions: m/z 357.2, 358.2
Internal standard BPA-d16
Coastal waters
Derivatization BSTFA
Wastewaters
Greece
Surface waters
Decantation
LC-MS/MS, RP, ESI, API
2 ng/L
3–175 ng/L
Loos et al. [31]
Column: Synergi Polar RP
SPE (Oasis HLB)
Mobile phase: water/acetonitrile
Wastewaters
Elution with ethanol/acetone/ethyl-acetate (2:2:1)
Precursor ion: m/z 227
Italy-Belgium
Product ions: m/z 133, 212
Lagoon water
SPE (ENVI-18)
HPLC-MS, ESI
1 ng/L
BDL-145 ng/L
Pojana et al. [32]
Column: C8-2
Mobile phase: gradient A acetonitrile B water
Elution with acetonitrile, methanol, water
Internal standard BPA-d16
Italy
Precipitation
LLE with dichloromethane
LC-MS, ESI, NI
5 ng/L
bdl-357 ng/L
Peters et al. [33]
The Netherlands
Column: Symmetry C18
Surface waters
Filtration
GC-MS
14 ng/L
BDL-330 ng/L
Belfoid et al. [34]
Column: SGE BPX5
Diagnostic ions: m/z 357
Internal standard: BPA-d16
SPE (SDV-XC disks)
Elution with methanol
Derivatization with SIL A
The Netherlands
Wastewater
Filtration
LC-MS/MS, NI, MRM
2 ng/L
0.15–1.55 μg/L
Mauricio et al. [35]
5 μg/L
Column: Purospher STAR RP-18
Mobile phase: gradient A methanol B water
SPE (Oasis HLB)
Precursor ion: m/z 227
Product ions: m/z 133, 211
Internal standard: oxybenzoic acid
ELISA
Portugal
Elution with dichloromethane
Surface waters
Filtration
HPLC-MS, ESI, NI
0.09 μg/L
BDL-2.97 μg/L
Céspedes et al. [36]
Column: 100RP-18
0.06–1.51 μg/L
Mobile phase: gradient A methanol B water
SPE (Lichrolut RP-18)
Diagnostic ions: m/z 227
Internal standard: 4-heptylpheno
Elution with acetonitrile
Wastewater
Spain
BDL below detection limit
Table 2.4

Analytical methods and levels of BPA in food samples
Samples
Pretreatment
Analytical method
LOD
Concentration of BPA
Reference
Bottled water
LLE with dichloromethane
GC-MS, EI
2.3 ng/L
3.5–150 ng/L
Nathanson et al. [12]
Column: 5 % diphenyl-95 % dimethyl polysiloxane
Derivatization BSTFA
Diagnostic ions: m/z 357.2, 358.2
Internal standard BPA-d16
Bottled water
SPE (OASIS HLB or C18)
GC-MS, EI
0.005 μg/mL
bdl-0.011 μg/L
Inoue et al. [76]
Column: HP 5MS
Elution two steps
Diagnostic ions: m/z 213, 119, 228
Internal standard: 4nNP
A dichloromethane/hexane (4:1 v/v)
B ethanol/dichloromethane (9:1 v/v)
Mineral water
SPE (OASIS HLB)
LC-MS/MS, ESI, NI, MRM
0.01 ng/L
BDL
Gallart-Ayala et al. [77]
Column: A symmetry C-18
Mobile phase: A methanol and B water
0.60 ng/L
Elution with methanol/dichloromethane
Precursor ion: m/z 227.2
Product ions: m/z 93.1, 133.4, 212.4
Soda beverages
Canned soft drink products
SPE (C18)
GC-MS, EI
27–74 ng/L
0.032–4.5 μg/L
Hennion [51]
Column: HP 5MS
Diagnostic ions: m/z 213, 228, 270, 312
Elution acetonitrile-water (1:1 v/v)
Internal standard: BPA-d16
Soft drinks/beers
DLLME
GC-MS, EI
5 ng/L
BDL-4.7 μg/L
Joskow et al. [17]
Column: HP 5HT, HP 5MS
Diagnostic ions: m/z 213, 228, 270, 312
Internal standard: BPA-d16

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Oct 30, 2015 | Posted by in General Dentistry | Comments Off on Analytical Methods for Determination of Bisphenol A
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