Impingers, glycol

No firm conclusions can be reached concerning detection limits with the resins or foam, since these vary so much with the rigor of cleanup, the chemicals tested, and the particular air environment. It appears, however, that both materials can achieve detection limits of 0.01 ng/nr under the most favorable conditions when employed in high-volume samplers, while the limit for the glycol impingers is on the order of 0.1 ng/m ... 

Summarizing, it appears that the macroreticular resins such as XAD-2, XAD-4, and Chromosorb 102 or porous polyurethane foam can be considered as alternatives to the glycol impinger for sampling many of the common pesticides and related chemicals in air. The glycol impinger has been more thoroughly tested, while the resins and foams are clearly to be preferred... 

Atrazine Herbicides. The herbicides, atrazine and cyanazine, may be analyzed by HPLC. Samples collected as filter wipes (Whatman 41), on Florisil tubes, or in ethylene glycol impinger solutions have been analyzed. Florisil tubes and wipe samples are extracted with acetonitrile and the resulting extracts injected directly into the HPLC system. Ethylene glycol impinger solutions are extracted with chloroform, concentrated by evaporation, and taken up in acetonitrile and the resulting solution used for HPLC injection. HPLC analyses are achieved as follows ... 

A S S S141 S214 S166 Diisopropylamine Dinitrobenzene (all isomers) Dinitro-o-cresol 20 1 0.2 Impinger/ 0.1 N HjSO MCEF/Bubbler (Ethylene glycol) 0.3 N KOH GC/F1D HPLC HPLC 8.5-37.4 0.42-2.4 0.070-0-62... 

Alternatively, air bubbled through impingers contain 0.1 jVH2S04 ethylene oxide converted into ethylene glycol latter measured by GC-FID (Romano and Renner, 1979). 

Shell side corrosion is caused by decomposition of the bath. (The decomposition products of amines and glycols are corrosive.) Some decomposition and corrosion are inevitable however, excessive decomposition is usually due to overheating near the firetube. Corrosion inhibitors are commonly added. There are numerous reasons for overheating the bath localized ineffective heat transfer caused by fouling, excessive flame impingement, etc. An improper flame can sometimes be modified without system shutdown. Fouling, however, requires removal of the firetube. 

Some compounds have low enough volatility and are soluble enough to be collected by absorption in a solvent. Vinyl acetate has been collected in toluene and isooctane can be used for the collection of aromatics such as ethyl benzene, styrene and pesticides. Ethylene glycol has also been used to collect pesticides. A colorimetric method was developed by Palassis for tetramethyl and ethylene thiourea. Samples were collected in impingers containing water and derivatized with penta-cyanoamineferrate to form a colored coordination complex. 

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