Page 16 - Shimadzu Journal vol.7 Issue1

Environmental Analysis

New technology simplifies analytical methods
GCMS methods for environmental monitoring were introduced into
the US by the USEPA in 1976 as a proposal to rapidly screen for
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organic priority pollutants . In screening for semi-volatile compounds,
the GC methods require a preliminary extraction into an organic
solvent. Later methods, such as EPA method 525.2, replaced
liquid-liquid extraction (LLE) with Solid Phase Extraction (SPE). SPE
lowered solvent use, but still burdens laboratories with preliminary
extractions. Table 6 lists USEPA liquid chromatography with tandem
mass spectrometry (LC-MS/MS) methods that require SPE extraction.

Table 6 EPA LC-MS/MS Methods
&1" NFUIPE 5JUMF
Determination of Selected Perfluorinated Alkyl Acids in
Drinking Water by Solid Phase Extraction and Liquid
Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Determination of Selected Organic Chemicals in Drinking
Fig. 4 MDL comparison of semi-volatiles between the GCMS-QP2020 and the Water by Direct Aqueous Injection-Liquid
GCMS-TQ8040 in full scan mode Chromatography/Tandem Mass Spectrometry (DAI-LC/MS/MS)
In this new ASTM method for pesticides and PCBs, laboratories are Determination of Hormones in Drinking Water by Solid Phase
Extraction (SPE) and Liquid Chromatography Electrospray
able to extract their samples just as they would for method 625.1 and Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS)
analyze for 625.1 either using a GCMS-TQ8040 in single quadrupole Determination of Selected Organic Chemicals in Drinking
mode, or using a single quadrupole instrument such as the Water by Solid Phase Extraction and Liquid
Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
GCMS-QP2020. This new ASTM method will save laboratories time
and effort by eliminating an entire extraction, solvent exchange, and Determination of Microcystins and Nodularin in Drinking Water
by Solid Phase Extraction and Liquid Chromatography/Tandem
analytical run on the GC-ECD. Instead, laboratories will be able to Mass Spectrometry (LC/MS/MS)
extract Method 625 as they normally would, and run semi-volatiles Determination of Cylindrospermopsin and Anatoxin-a in
and pesticides and PCBs with that single extraction. Drinking Water by Liquid Chromatography Electrospray
Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS)
In developing the method, we had no difficulty with single component
compounds, however, multiple component analytes, such as aroclors Shimadzu has published numerous application notes showing the
(PCBs) were a challenge. SSI Solution Center personnel developed an benefits of LC-MS/MS and its ability to analyze low concentrations of
algorithm to qualitatively identify the best estimate for the aroclors' various pollutants without preliminary SPE. These pollutants include
identity and calculate their concentration. This approach is microcystins, pharmaceutical and personal care products (PPCP), per
summarized in the flow chart in Fig. 5 and polyfluorinated alkyl substances (PFAS), and pesticides and
herbicides.
Data acquisition with wide window
SSI is collaborating with ASTM to develop and validate LC-MS/MS
methods that eliminate, or minimize extraction in favor of direct
injection. In particular, we are leading the industry in new methods for
Integrate whole peaks Build calibrations with one the analysis of PFAS, including ASTM D7979 Standard Test Method
as one peak compound for each
chlorobiphenyl for Determination of Per- and Polyfluoroalkyl Substances in Water,
(mono to nona) Sludge, Influent, Effluent and Wastewater by Liquid Chromatography
Calculate concertation of each Tandem Mass Spectrometry (LC/MS/MS) , and D7968 Standard Test
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chlorobiphenyl (mono to nona)
Method for Determination of Polyfluorinated Compounds in Soil by
Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS) .
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Calculate concentration ratio of each
chlorobiphenyl (mono to nona) PFAS are a group of chemicals of growing concern because of their
worldwide occurrence in groundwater supplies. Both ASTM methods
are external standard calibrations. Instead of SPE, ASTM D7979
Identify Aroclors referring to
®
concentration ratio from standards collects small volumes of sample and adds methanol directly into the
sample vial eliminating loss of sample to the container walls. The small
Calculate reference concentration ratios
Summation of all chlorobiphenyls of all Aroclors® using standard solutions sample volume saves on shipping costs. Results are equal to, or better
is concentration of Aroclors ® (These ratios can be used permanently) than, solid phase extraction and are available in a fraction of the time
(Fig. 6). Fig. 7 is a schematic of the extraction process of ASTM
Fig. 5 Estimating aroclor identity and concentration by GC/MS/MS D7979.
Using the approach in Fig. 4, preliminary single laboratory data
extracted and correctly identified Aroclor-1232 at the concentrations
and recovery shown in Table 5. Extract Evaporate Analyze a batch by EPA 537
Table 5 Recovery of Aroclor -1232 in select matrices and concentrations
&⒐VFOU 8BUFS 3JWFS 8BUFS Analyze a batch by ASTM Analyze a batch by ASTM
"SPDMPS
4QJLFE ŸH - 4QJLFE ŸH - 4QJLFE ŸH - 4QJLFE ŸH - D7979 D7979
1$# 4FU
1$# 4FU
Fig. 6 Comparison of analysis time between SPE methods and ASTM D7979 for PFAS

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