Extraction of Volatile Organic Compounds from Solids and Liquids

Determination of Volatile Substances in Forensic Samples by Static Headspace Gas Chromatography

“…This is achieved by grinding the solid to a powder as fine as possible, or dissolving or dispersing the solid into a liquid. In the first case, the contact volume of the solid is increased in order to establish a better partition between the volatile substance and the headspace gas; however, it is preferred to dissolve the solids in a liquid, because equilibrium is achieved faster this way, and is also more reproducible; on top of that, liquid samples are easier to work with (Slack, et al, 2003).…”

“…Liquid samples are usually simply poured into a vial and sealed immediately after, in order to prevent any evaporation losses (Slack, et al, 2003).…”

“…The partition coefficient depends on the extraction temperature, while  is determined by the relative volume between the two phases; In static headspace extraction the sensitivity depends on the solubility of the analyte in the matrix; for analytes with a high partition coefficient, the most important parameter is the extraction temperature, since most of the analyte is in the liquid phase and it can only be passed into the headspace by heating the vial; on the other hand, for analytes with low partition coefficients, they are already present in the headspace even without any heating, so in this case, the most important parameter is the volume relation between the phases. That is, increasing the extraction temperature is only effective in polar volatile analytes, while the sensitivity of non-polar analytes remains essentially unchanged by the increase of the extraction temperature (Slack, et al, 2003).…”

“…If the values of K are not known, one can simply analyze in the chosen matrix the substance to be determined, as well as determining the area against the sample volume (Slack, et al, 2003).…”

“…This paper will review theoretical aspects of the static headspace technique, as well as complementary additions to it (Kolb, 1999;Slack et al, 2003), the most significant substances from the standpoint of forensic toxicology that can be analyzed by this technique as ethanol (Kugelberg & Jones, 2007;Macchia et al, 1994;Tagliaro et al, 1992), congeners of alcoholic beverages (Iffland & Jones, 2003), inhalants (Angerer & Horsch, 1992;Seto, 1994), anesthetics (Pihlainen & Ojanperä, 1998), carbon monoxide (Boumba & Vougiouklakis, 2005;Vreman et al, 1984) and cyanide (Calafat & Stanfill, 2002;Felby, 2009); in each case, the analytical conditions and modifications necessary for the equipment to perform each analysis will be exposed, advantages and disadvantages of this technique over other existing procedures will be discussed and also, issues relating to development of methods for this technique and their validation.…”