Detection and identification of volatile substances by headspace capillary gas chromatography to aid the diagnosis of acute poisoning
Headspace gas chromatography with split flame-ionization–electron-capture detection is a simple method of screening for a wide range of volatile substances in biological fluids. A 60m × 0.53 mm i.d. thick-film (5µm) fused-silica capillary coated with SPB-1 (Supelchem) with split flame-ionization–electron-capture detection provides a valuable alternative to packed columns in this work. Most commonly abused compounds, including many with very low boiling-points such as bromochlorodifluoromethane (BCF), butane, dimethyl ether, FC 11, FC 12, isobutane and propane, can be retained and differentiated at an initial column temperature of 40 °C followed by programming to 200 °C. The total analysis time is 26 min. Retention and detector response data were generated for 244 compounds. Good peak shapes are obtained for polar analytes such as ethanol and injections of up to 0.30 cm3 of headspace can be performed with no discernable loss of efficiency. The sensitivity is thus at least as good as that attainable with packed columns. Of the commonly encountered compounds, only isobutane–methanol and paraldehyde–toluene are at all difficult to differentiate. Quantitative measurements can be performed either isothermally or by using the temperature programme.