Physical evidence in drug intelligence. Part 3: Supercritical fluid extraction-high performance liquid chromatography of packaging tapes

It may be desirable to compare samples of packaging tape or identify their specific brand and/or model based on analytical results. Such information may, for example, be used to infer or refute hypotheses of common origin for separately seized packages of illicit drugs. The potential of supercritical fluid extraction (SFE) was investigated by extracting additive material from samples of packaging tape and analysing them by high performance liquid chromatography (HPLC). Although both colorless and opaque tape samples were initially tested, results are only presented for the former, as opaque samples presented additional difficulties with carryover. Prior classification of the adhesives by Fourier transform infrared (FTIR) spectroscopy and pyrolysis gas chromatography mass spectrometry (PyGCMS) allowed correlation of results based on this characteristic, and the technique was found to be particularly successful on tape samples with a rubber-based adhesive. For these, the chromatography was qualitatively reproducible and notably different results were obtained for different samples. Tapes with an acrylic-based adhesive, however, produced consistently inconclusive results. The concept of differentiating tape samples through the analysis of extracts was shown to be generally sound; however, further method development is required to extend the applicability of the technique to operational situations.