The Analysis of Dioxins and Furans Using HRGC-High Resolution MS with the AutoSpec-Ultima NT

This application note gives examples of the performance of the Waters Micromass AutoSpec Ultima NT and describes QuanLynx Application Manager, the most advanced quantification software for dioxin and furan analysis, illustrating why this combination is the market leader in the field.

‘Dioxins’ refers to a group of chemical compounds that share certain similar chemical structures and biological characteristics. Several hundred of these toxic compounds exist and are members of three closely related families: the polychlorinated dibenzop-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and certain polychlorinated biphenyls (PCBs).

Sometimes the term dioxin is also used to refer to the best studied and one of the most toxic dioxins, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). PCDDs and PCDFs are not created intentionally, but are produced inadvertently by a number of human activities. Natural processes also produce PCDDs and PCDFs.

Over the past decade, regulatory environmental agencies and industries have worked together to dramatically reduce dioxin emissions. Because dioxins are extremely persistent compounds, levels of dioxins still exist in the environment from both man-made and natural sources and will take years to decline.

The detection and quantification of dioxins is a particularly demanding analysis due to the low level of regulatory exposure limits and the variety of complex sample matrices encountered. High Resolution Gas Chromatography (HRGC), coupled with High Resolution Mass Spectrometry (HRMS) offers the high sensitivity, selectivity, and quantitative dynamic range for this application and as such, is the technique of choice.

This application note gives examples of the performance of the Waters Micromass AutoSpec Ultima NT and describes QuanLynx Application Manager, the most advanced quantification software for dioxin and furan analysis, illustrating why this combination is the market leader in the field.

Regulatory Considerations

Across the world, there are many different legislative methods for dioxin and furan analysis, including US EPA method 1613, European method EN1948, Canadian EPS1/RM/19 and other variants of these.

In the UK and across much of Europe, there is no specific legislative method for the analysis of dioxins and furans. In UK-based laboratories, for example, methods using the extraction and clean-up processes of US EPA method 1613 and the labeled internal standard mixtures of US EPA method 23 are employed for the analysis of all environmental samples other than those obtained by air emission sampling.

The general common factor is the use of labeled internal standards for quantification and determination of recoveries, the use of resolutions in excess of 10,000 resolving power (5% height, 10% valley definition) coupled with a 60 m GC column, either DB5, SP2331 or similar.

While the procedures and results described in this application note are intended to show the performance of the AutoSpec Ultima NT for dioxin and furan analysis, this could be as easily applied following any legislative method explicitly.

In preparation for the analyses, the AutoSpec Ultima NT was tuned to in excess of 10,000 resolutions at electron energy of 30 eV, before calibration over the mass range for the experiment was acquired. The experiment used was a standard EPA1613 five-function voltage selected ion recording (VSIR) acquisition system. The calibration is performed on a daily basis and by keeping a hardcopy record of the per-fluorokerosene (PFK) peaks during calibration, a permanent record of instrument resolution is maintained which is essential for the level of auditing in a modern accredited laboratory.

First, a single function survey injection was performed to determine the acquisition time windows for the multifunction analysis.

Next, a sample list was set up to include a solvent blank injection of nonane, a CS1 to CS5, five-point calibration using standard EPA1613 standard sets. After the calibration, more nonane solvent blank injections were included, before the sample extract injections were to be performed. The sample list is shown in Figure 1.

The samples were spiked with labeled internal standards similar to those used for US EPA method 23, having one labeled standard for each level of chlorination for each group of congeners i.e. ¹³C-2,3,7,8-TCDF and ¹³C-TCDD for the tetra dioxins and tetra furans. ¹³C-1,2,3,4-TCDD and ¹³C-1,2,3,7,8,9-HxCDD were added as recovery standards.

The sample list was then started and the data acquired and processed automatically using QuanLynx 4.0.

All acquisition and data processing was performed using MassLynx 4.0 and QuanLynx 4.0 Software.

Figures 2 and 3 show the calibration curves for 2,3,7,8-TCDD and OCDD illustrating excellent quantitative linearity.

Table 1 shows a summary of the calibration curves. It can be seen that the RRF % relative standard deviations are well within the regulatory limits of <15% (US EPA method 1613 and most European methods) and <10% (Japanese and some other methods).

Similarly, the Total WHO-TEQ LOD falls well below the regulatory level required for dioxin analysis illustrating the unmatched sensitivity of the AutoSpec Ultima NT.

The results from the quantitative data processing are stored and displayed for ease of review in the QuanLynx browser.

Figures 4 and 5 show views of the QuanLynx browser for the hexa-furans in a calibration curve standard and in a real sample respectively.

Figures 6 and 7 show data for the tetrafurans and hexa-dioxins in the real sample.

Location and review of sample data is made easier using the numerous dioxin dedicated features included in QuanLynx. Figure 8 shows ‘Congener Select’, a drop-down menu provided to allow the user to quickly locate and view quantitative results for a particular congener.

After data acquisition and processing various options are available, including export of results in various forms for reporting purposes, storage of calibration for future use and/or acceptance and locking of the data set to prevent modification of processing results (see Figure 9).

High Resolution Gas Chromatography (HRGC) coupled with High Resolution Mass Spectrometry (HRMS) is the analytical technique of choice for analysis of dioxins and furans. The Micromass AutoSpec Ultima NT is the market-leading instrument of choice, offering the ultimate sensitivity, quantitative linearity, reproducibility necessary for regulatory dioxin and furan monitoring. In addition, MassLynx 4.0 and QuanLynx 4.0 give unprecedented automation, ease-of-use, data acquisition, and processing functionality with numerous features dedicated to dioxin and furan analysis.

Please see the Micromass website at www.micromass.co.uk for details of the latest technological developments and applications of the Micromass AutoSpec Ultima NT.