DETERMINATION OF CYCLIC ORGANIC-ACID ANHYDRIDES IN AIR USING GAS-CHROMATOGRAPHY .1. A REVIEW

Gas chromatographic methods for the determination of cyclic organic ac id anhydrides (OAAs) in industrial air are reviewed, The OAAs discusse d are phthalic, hexahydrophthalic, methylhexahydrophthalic, tetrahydro phthalic, methyltetrahydrophthalic, trimellitic, maleic, and octenylsu ccinic anhydride, Solid sorbent sampling methods, using Amberlite XAD- 2 or Tenax, are used for sampling of OAA vapour, These methods are eas y to use, have simple work-up procedures and sample the anhydrides as such, However, many OAAs are reactive compounds and losses during stor age should be considered, Sampling of OAAs in mixed exposure of partic les and vapour are performed by either bubblers or impingers with aque ous sampling solutions or by filters in series with solid sorbent tube s. It can be assumed that non-polar filter samples an OAA as such, Hen ce these methods are easy to use, but losses during storage must be co nsidered, Bubblers/impingers convert the OAAs into the corresponding a cids 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 ionizatio n detection (FID), electron-capture detection (ECD) and MS using elect ron impact or negative-ion chemical ionization, Typical detection limi ts for determinations of OAAs as such are 0.1 mu g of OAA per sample u sing FID and an order of magnitude better using ECD or MS, For determi nation of the esters from the corresponding OAAs using MS, the detecti on Limits are better than 0.01 mu g of OAA per sample. Precisions are normally better than 10%.