Sourcing the provenance of cannabis crops using inter-element association patterns ‘fingerprinting’ and laser ablation inductively coupled plasma mass spectrometry

(Note: The full text of this document is currently only available in the PDF Version )

R. John Watling


Abstract

This paper describes the development and application of laser ablation ICP-MS methodologies for determining the trace element association patterns ‘fingerprint’ of cannabis crops and the potential tracing of these crops to specific geological environments. It also details the specific identification of single- and multi-sourced material collected during police drug raids. Cannabis samples are ground to a fine powder under liquid nitrogen and the resulting material pressed, under 20 t pressure, into cardboard mounts. An Nd:YAG laser is used to ablate this pressed powder and high sensitivity ICP-MS is used to determine the elemental association patterns ‘fingerprint’ derived from the analysis of the material. These associations of elements, rather than the traditional element concentrations, form the basis of the approach for the determination of provenance of cannabis crops and samples recovered in individual police drug raids. Variations in analyte signal between different ablation events, because of variations in coupling and transport efficiency, number of shots and morphology and colour of the substrate, are obviated by the use of ternary ratio per cent. discriminant diagrams. Ternary ratio per cent. plots represent the direct comparison of the relationship between three components in a system. The use of these plots effectively eliminates any variability in absolute values by concentrating on inter-comparison of components rather than absolute values. Positioning a ratio per cent. data point anywhere within the ternary plot indicates the relative percentile inter-association of the three components defined by the diagram. Using this method all ternary association plots of elements from the same sample will plot in the same position on the diagram, whereas those from different samples will plot elsewhere. Reproducibility on a day to day basis is confirmed by analysis of in-house standard cannabis materials with each sample batch.


References

  1. L. Moenke-Blankenburg, Laser Microanalysis, Wiley, Toronto, 1989 Search PubMed.
  2. L. Moenke-Blankenburg, Spectrochim. Acta Rev., 1993, 15, 1 Search PubMed.
  3. H. P. Longerich, S. E. Jackson, B. J. Fryer and D. F. Strong, Geosci. Can., 1991, 20(1), 21 Search PubMed.
  4. A. L. Gray, Analyst, 1985, 110, 551 RSC.
  5. K. E. Jarvis and J. G. Williams, Chem. Geol., 1993, 106, 251 CrossRef.
  6. M. Paul, At. Spectrosc., 1994, 15(1), 21 CAS.
  7. E. H. Piepmeier, Analytical Applications of Lasers, WileyNew York, 1986 Search PubMed.
  8. C. Geertsen, A. Briand, F. Chartier, J.-L. Lacour, P. Mauchien, S. Sjostrom and J.-M. Mermet, J. Anal. At. Spectrom., 1994, 9, 17 RSC.
  9. Y. Huang, Y. Shibata and M. Morita, Anal. Chem., 1993, 65, 2999 CrossRef CAS.
  10. R. R. Brooks and C. C. Radford, Proc. R. Soc. London, Ser. B, 1978, 200, 217 Search PubMed.
  11. A. J. M. Baker and P. L. Walker, in Heavy Metal Tolerance in Plants: Evolutionary Aspects, ed. Shaw, A. J., CRC Press, Boca Raton, FL, 1989, p. 155 Search PubMed.
  12. C. E. Dunn, in Noble Metals and Biological Systems, ed. Brooks, R. R., CRC Press, Boca Raton, FL, 1992, p. 47 Search PubMed.
  13. A. J. M. Baker, C. J. Grant, M. H. Martins, S. C. Shaw and J. Whitterrook, New Phytol., 1986, 102, 575 Search PubMed.
  14. S. Chenery, A. Hunt and M. Thompson, J. Anal. At. Spectrom., 7, 647 Search PubMed.
  15. K. Dittrich and R. Wennrich, Prog. Anal. Spectrosc., 1984, 7, 139 Search PubMed.
  16. M. Thompson, S. Chenery and L. Brett, J. Anal. At. Spectrom., 1990, 5, 49 RSC.
  17. E. F. Cromwell and P. Arrowsmith, Anal. Chem., 1995, 67, 131 CrossRef CAS.
  18. P. Arrowsmith and S. K. Hughes, Appl. Spectrosc., 1986, 40, 274.
  19. E. R. Denoyer, in Applied Plasma Source Mass Spectrometry, ed. Holland, G., and Eaton, A. N., Royal Society of Chemistry, Cambridge, 1990, p. 199 Search PubMed.
  20. S. F. Durrant, Analyst, 1992, 117, 1585 RSC.
  21. H. Scholze, E. Hoffmann, C. Lüdke and A. Platalla, Fresenius' Anal. Chem., 1996, 355, 892 Search PubMed.
  22. E. Hoffmann, C. Lüdke and H. Stephanowitz, Fresenius' J. Anal. Chem., 1996, 355, 900.
  23. R. J. Watling, H. K. Herbert and I. D. Abell, Chem. Geol., 1995, 124, 67 CrossRef.
  24. R. J. Watling, H. K. Herbert, I. S. Barrow and A. G. Thomas, Analyst, 1995, 120, 1357 RSC.
  25. R. J. Watling, H. K. Herbert, D. Delev and I. D. Abell, Spectrochim. Acta, Part B, 1994, 49, 205 CrossRef.
  26. A. J. Walder, I. D. Abell, I. Platzner and P. A. Freedman, Spectrochim. Acta, Part B, 1993, 48, 397 CrossRef.
  27. L. Moenke-Blankenburg, T. Schumann, D. Gunther, H.-M. Küss and M. Paul, J. Anal. At. Spectrom., 1992, 7, 251 RSC.
  28. A. Raith, J. Godfrey and R. C. Hutton, Fresenius' J. Anal. Chem., 1996, 354, 163 CAS.
  29. M. D. Norman, N. J. Pearson, A. Sharma and W. L. Griffin, Geostand. Newsl., 1996, 20, 247 CrossRef CAS.
Click here to see how this site uses Cookies. View our privacy policy here.