Environmental Analysis 35 GCxGC-TOFMS Results Table 3. EDC’s & Pollutants Detected
Figure 1:The two dimensional contour plot chromatogram above shows the 108 component endocrine disruptor reference standard used to develop the SPE extraction procedure and GCxGC-TOFMS method. The on-column concentration for each component is 5 nanograms.
Expanded Peak Capacity and Resolution of GCxGC
Figure 2: The example above shows the 2D Contour Plot for 2 peaks that are resolved in the second dimension by 105 milliseconds yet coeluted completely in the 1st dimension separation at 1764s. The expanded peak capacity and advantage of a two-dimensional separation is illustrated by this example of two chemically similar pesticides that would be coeluted and difficult to characterise by one dimensional chromatography. Notice the high mass spectral match scores by the NIST 08 library searches of 84%and 90.5% for both compounds.
Conclusions
In conclusion, comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was utilised in this research to detect endocrine disruptors, personal care products, as well as other pollutants in samples obtained from urban and rural point sources along a Midwestern watershed. A solid phase extraction method was developed using a hydrophilic modified styrene based polymer for a broad range of compounds from aqueous samples. An optimised GCxGC method was developed using a conventional non-polar and mid-polarity column set. The GCxGC method utilised variable modulation which aids in optimisation of the available peak capacity and chromatographic resolution of the first and second dimension separation. A TOFMS method was created which offers continuous full range non-skewed mass spectral information, True Signal Deconvolution®, and fast acquisition rates ideal for the characterisation of EDCs and other contaminants in water.
Thirteen solid phase extractions were conducted on 1 liter aqueous samples obtained from 6 different rural and urban point sources along a Midwestern watershed. GCxGC-TOFMS analysis was followed by data processing that utilised the “Reference” feature in ChromaTOF software. The final reference developed to detect EDCs contained 152 compounds which was applied as part of the data processing method. Results of this research detected 102 chemicals in aqueous extractions from 6 different point sources along the watershed. The detected compounds matched the reference standard with at least a 60% library match similarity. Furthermore, results show that 81% of the 102 chemicals
Table 3
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