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(2) Sampling and analysis
[Results]
Bisphenol A used as a resin monomer, phthalic acid esters used
as plasticizers, and alkylphenols used for manufacture of
surfactants are attracting public attention for their high
exposure levels. Risk analysis for these substances needs the
estimation of exposure to humans in addition to the evaluation
of effects on organisms. For this purpose, a high-sensitivity
measurement method of human samples and basic studies on
acquisition and storage of samples are needed.
As in other microanalytical processes, contamination of the
sample before the measurement must be prevented.
For the three analytes mentioned above existing in biological
samples, a high-sensitivity analytical procedure was developed,
and a guideline for analysis of endocrine disruptors in
biological samples was established.
The following points were considered in the development. (i)
The analytical method must have a very high sensitivity because
very low concentrations (in an order of ppb) of chemical species
in a very small quantity of samples. Chromatography that allows
simultaneous determination of many components is indispensable
for this purpose.
(ii) Mass spectrometry is the only means that permits reliable
identification of chromatographic peaks yielded by a very small
quantity of the sample, as required in the analysis of endocrine
disruptors. The GC/MS and LC/MS procedures were adopted
because advances in mass spectrometry have made it possible to
fulfill the two requirements above. The LC/MS/MS configuration
consisting of the new tandem mass spectrometer and the liquid
chromatograph has achieved even higher sensitivity and
precision. These cutting-edge technologies are indispensable to
establish an analytical procedure of sufficiently high
sensitivity and reliability.
Blank tests were postulated in order to minimize contamination.
Background signal levels also must be minimized by cleaning the
instruments and tools, baking glassware, introducing the column
switching technique in a closed system for sample pretreatment,
and employing an essential oil distillator.
Furthermore, it was made clear that PVC gloves or sample
containers should be tested if they contain the analytes to
check the background level. A cross check may be needed if a
value significantly higher than the result is obtained.
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