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dimension of the column without affecting the elution characteristics of neighbouring peaks. Early indications are that this technique can yield at least a factor of tenfold increase in signal intensity. Another major advantage of the time controlled CZC approach is that due to its simplicity and flexibility standard analysis and CZC experiments can be combined within one analysis sequence and even within the same measurement.
Although further work in optimisation of this technique is required; combining time controlled CZC with the sensitive and selective detection of high resolution mass spectrometry could push absolute instrumental detection limits from low femtogram down into the attogram range for specific POPs including 2378-TCDD.
Such detection limits are congruous with those required for detection of trace persistent organic pollutants (POPs), such as dioxins, in dried blood spots. Further investigations are planned to investigate the feasibility of this technique for this application.
Acknowledgements
The authors would like to thank the following people for advice and contributions towards the work in this paper; Jean-Francois Focant (University of Liege); Don G. Patterson Jr. (Exponent); Brock Chittim (Wellington Laboratories); Wayman Turner and Andreas Sjödin (Centers for Disease Control and Prevention)
References
[1] Huebschmann, H-J., Handbook of GC-MS: Fundamentals and Applications, Second Edition, Wiley-VCH Verlag GmbH, Weinheim, 2009, p.1
[2] Fernandes, A., White, S., D’Silva, K., Rose, M., Talanta, 63 (2004) 1147–1155
[3] L’Homme, B., Brasseur, C., Focant, J-F., Organohalogen Compounds, 73 (2011) 1142-1145
[4] Liu, Z., Phillips, J.B., Journal of Chromatographic Science, 29 (1991) 227
[5] Marriot, P.J., Ong, R.C.Y., Kinghorn, R.M., Morrison, P.D., Journal of Chromatography A, 892 (2000) 15–28
[6] Yang, S-O., Kim, Y., Kim, H-S., Kim, S-H., Kim, S-H., Choi, H-K., Marriot, P.J., Journal of Chromatography A, 1218 (2011) 2626–2634
[7] Focant, J-F., Pirard, C., Eppe, G., De Pauw., Journal of Chromatography A, 1067 (2005) 265–275
Figure 9: sensitivity increase for native PCDF with CZC in low level pooled blood sample ca. 30 fg PCDF; ); left - standard analysis; right - CZC experiment; mass traces analogue to Figure 7, only for PCDF
[8] Patterson Jr., D.G., Welch, S.M., Turner, W.E., Focant, J-F., Organohalogen Compounds, 67 (2005) 107-109
[9] Patterson Jr., D.G., Welch, S.M., Turner, W.E., Sjödin, A., Focant, J-F., Journal of
Chromatography A, 1218 (2011) 3274–3281
[10] Pico, Y., Chapter 7 - New Approaches in Mass Spectrometry, Comprehensive Analytical Chemistry, Elsevier B.V., Volume 51, 2008, p.201-230
Figure 7: sensitivity increase with CZC in 1/10 EPA 1613 CSL standard (10 fg/ µL 2378-TCDD); left - standard chromatogram TCDD (mass trace 1 and 2: ratio /qualifier and quantification m/z for native (12
C) TCDD; trace 3: quantification m/z 13 right – chromatogram with cryo-focussed 2378-TCDD peaks, note: 1234-TCDD is not focussed.
C TCDD);
Figure 8: sensitivity increase for 2378-TCDD with CZC in low level pooled blood sample (ca. 10 fg/µL native TCDD); left - standard analysis; right - CZC experiment; all mass traces as explained in Figure 7
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