Determination of cyclic organic acid anhydrides in air using gas chromatography .1. A review

Gas chromatographic methods for the determination of cyclic organic acid anhydrides (OAAs) in industrial air are reviewed, The OAAs discussed are phthalic, hexahydrophthalic, methylhexahydrophthalic, tetrahydrophthalic, methyltetrahydrophthalic, trimellitic, maleic, and octenylsuccinic anhydride, Solid sorbent sampling methods, using Amberlite XAD-2 or Tenax, are used for sampling of OAA vapour, These methods are easy to use, have simple work-up procedures and sample the anhydrides as such, However, many OAAs are reactive compounds and losses during storage should be considered, Sampling of OAAs in mixed exposure of particles and vapour are performed by either bubblers or impingers with aqueous sampling solutions or by filters in series with solid sorbent tubes. It can be assumed that non-polar filter samples an OAA as such, Hence these methods are easy to use, but losses during storage must be considered, Bubblers/impingers convert the OAAs into the corresponding acids and glass-fibre filters do the same, at least in part, The acids are stable on storage but a derivatization must be performed before GC analysis, Detection methods used for the analysis are flame ionization detection (FID), electron-capture detection (ECD) and MS using electron impact or negative-ion chemical ionization, Typical detection limits for determinations of OAAs as such are 0.1 mu g of OAA per sample using FID and an order of magnitude better using ECD or MS, For determination of the esters from the corresponding OAAs using MS, the detection Limits are better than 0.01 mu g of OAA per sample. Precisions are normally better than 10%.