WHICH COMPOUNDS CAN BE DETECTED BY TD-GC-MS?

A broad range of Volatile Organic Compounds (VOC) can be detected with a GC-MS-analysis, e.g.: hydrocarbons (aromatic, aliphatic, cyclic), alcohols, ketones, aldehydes, esters, ethers, furans, organic acids, organic sulphur compounds (dimethylsulphide, dimethyldisulphide, …, thiols), chlorinated compounds, nitrogen containing compounds (amines, nitriles, pyridine), etc.…

The detectable compounds generally have a molecular mass in the range between 30 and 200/300. Detection also depends on volatility (vapour pressure/boiling point) of the compound. Compounds which are extremely volatile (e.g. methane, ethylene, …) will not be detected, since these are not retained on the adsorption tubes. Other factors influencing the detectability are among others the stability of the compound during sampling and analysis and the weight of the molecular fragments (detection starts at a mass of m/z=30, hence lighter fragments are not detected).

Following compounds cannot be detected:

• Compounds which are too volatile: most C1-C4 aliphatic hydrocarbons, methanol, methanal
• Some important (odorous) inorganic compounds like hydrogen sulphide and ammonia. To analyse these compounds a specific analytical method is required (GC or colorimetric methods)
• Too heavy compounds, like polyaromatic hydrocarbons, most aliphatic hydrocarbons with chain length of C16 or more; most alcohols, aldehydes, ketones etc. with chain length above C12

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