Novel method for direct analysis of hydrocarbons in crime investigation and air pollution studies

Abstract

MODERN methods for sampling of organic vapours in air pollution studies avoid the problems caused by the condensation of water vapour, by collection at ambient temperature on charcoal¹, porous polymers^2–5 or support-bonded phases⁵. The tenacity of adsorption renders the sample difficult to remove and indirect methods such as liquid extraction^1,5 or thermal desorption^2–4 are necessary to produce a sample for gas chromatographic (GC) or GC–mass spectrometric analysis. We describe here an analytical technique based on the Curie point pyrolysis system⁶ which overcomes these problems by using ferromagnetic wires coated with a thin layer of highly active charcoal. These are simply suspended in the atmosphere under test for 1–2 h at room temperature, placed in the Curie point apparatus and then inductively heated in the normal manner. Thus the sample is rapidly introduced into the GC for direct analysis. The fact that the total amount of each hydrocarbon present is not adsorbed by this method is outweighed by the advantages of direct sample introduction, which offers distinct advantages to the forensic scientist in the investigation of a suspected arson. The technique could also find quantitative application in air pollution studies.