Bisphenol A Environmental Exposure Research
Analytical Method Criteria
for the Determination of
Bisphenol A in Various Matrices
The following criteria are intended for an uncharacterized
matrix/site and could be modified based on the known
characteristics (history) of the matrix/site being sampled
and the method quantitation limit needed. The main goal
of these criteria is data integrity and is based on
extensive experience within the Bisphenol A Analytical
Research Task Group in determining bisphenol A (BPA)
in biological, environmental, and polymer extract matrices.
- All materials (analyte & internal standard),
solvents and reagents, including water, should be
of high enough purity as to not limit the method capabilities,
and be fully documented.
- Each sampling site should include a minimum of duplicates
(triplicates recommended) of the appropriate blanks,
controls, fortified controls, samples, and site-fortified
- Sample containers should be selected to ensure sample
integrity and large enough to allow reanalysis if
- Depending on the sample matrix and biological activity
it may be necessary to treat the samples with a preservative/stabilizer.
Concentrated HCl at ~1 mL/L is one treatment that
has been used successfully as a preservative in previous
surface water analyses.
- All sampling, sample treatment and shipment/storage
conditions should be documented using a detailed chain
of custody form that travels with the samples.
Preparation & Analysis:
- Multiple extractions should be performed to maximize
the recovery of any BPA in the sample matrix.
- As BPA is formed through an acid-catalyzed condensation
reaction of phenol and acetone, a combination of these
solvents should not be used.
- A method that employs simultaneous quantitation
and structural confirmation at the method quantitation
limit, such as gas chromatography/mass spectrometry
(GC/MS), is highly recommended. However, other (non
GC/MS) methods that meet or exceed the performance
criteria outlined in this document are acceptable.
- The use of internal standard(s) greatly improves
the method accuracy and precision. An internal standard
(IS) should be chosen based on accepted IS selection
criteria such as: a) the IS should be stable and not
interfere with the analyte, b) the IS should be as
similar in structure to the analyte as possible, which
ensures it will behave (extraction, concentration
) like the analyte, c) the IS should not be
present in the sample matrix. The above criteria have
led to the use of stable isotope internal standards
when MS techniques are employed. The use of D8-BPA
as an IS is strongly recommended and has been used
successfully in biological, environmental, and polymer
matrices. The use of other commercially available
stable isotope IS (e.g. D10-anthracene) may be used
when acceptable accuracy and precision are demonstrated.
- The method should be validated over the entire concentration
range reported using a fortified control sample matrix.
- Method validation should include a mass balance
experiment to determine the absolute method recovery.
- Elevated temperatures during sample extraction,
concentration, chemical derivatization, or injection
can increase the chance of BPA analogs to thermally
degrade and produce false positives. If elevated temperatures
are used in any portion of the method, the appropriate
controls/experiments must be conducted to demonstrate
data integrity. Derivatization reagents that can hydrolyze
or transesterify BPA analogs should not be used. This
in particular is the case for tetramethyl ammonium
hydroxide (TMAH) and trimethyl sulfonium hydroxide
- Matrix standards (minimum 3 point, recommended 5
point calibration) should be prepared with each sample
set, encompass the full range of quantitation, and
include the appropriate blanks, controls, and isotopic
Data Analysis & Report:
- The final report should be detailed enough (methods,
instrumentation, and parameters) to allow duplication
of reported data by a qualified laboratory.
- When MS with stable isotope internal standard techniques
are used, appropriate isotopic crossover calculations
must be applied following the method of Barbalas and
- The relative method recovery (internal standard
corrected) should be 80 % to 120 % and the precision
should be 20 %. Blanks should not exceed more than
20 % of the value of concern (amount of BPA in the
sample, lowest standard at calibration or method quantitation
limit). The results should be corrected for the blank
- The method must include some form of confirmation
of the BPA chromatographic peak. It is preferred that
the confirmation be based on structural information
such as accurate mass, daughter ions or ion ratio
obtained from MS techniques. Using a GC/EI/MS methodology,
the confirmation ratio for underivatized samples would
be calculated using the molecular ion peak (M+) with
a mass-to-charge ratio (m/z) of 228, and the base
peak (loss of a methyl group, M-CH3+) with m/z equal
to 213. The formula is as follows: (abundance of 228/abundance
of 213) x 100. The appropriate ions should be used
for derivatized samples. The confirmation ion ratio
precision should be ( / Less than or equal to) 20%
between standards, fortified samples, and positive
samples. Confirmation techniques other than MS, such
as high performance liquid chromatography (HPLC) with
fluorescence detection or diode array ultraviolet
(UV) detection, or chromatographic multi-column separation,
may be adequate based on the method quantitation limit
needed and the prior knowledge of the nature of the
- The method quantitation limit is set based on the
lowest standard and fortified sample that meet the
method performance criteria set in points 3 and 4
of this section. The linearity of the calibration
must be checked.
Barbalas, M.P. and Garland, W. A. (1991). J. Pharm.
Sci., 80, 922-927.
These criteria were prepared by the Bisphenol A Analytical
Research Task Group, a subgroup of the Bisphenol A Global
Industry Group, which operates under the auspices of
the American Plastics Council (APC), the Association
of Plastics Manufacturers in Europe (APME), and the
Japan Chemical Industry Association (JCIA).