CORRELATION OF ELECTRON-CAPTURE RESPONSE ENHANCEMENTS CAUSED BY OXYGEN WITH CHEMICAL-STRUCTURE FOR CHLORINATED HYDROCARBONS

The enhancement of response to 32 simple chlorinated molecules of a constant-current electron capture detector (ECD) caused by the addition of oxygen to its carrier gas has been determined. The effects of size and isomeric differences for alkyl, vinyl, allyl, and phenyl chlorides are examined. Also, the oxygen-induced enhancements of several chlorofluoro-methanes are reported. From these data, general trends of structural differences emerge which facilitate the prediction of where oxygen-doping in ECD analyses might be gainfully applied. These data are discussed in terms of a mechanism which was previously proposed and is further developed here into a detailed model of the instrument's response. Response enhancements are attributed to assistance provided by O2-in the overall electron capture process. It appears that relative rates of the reaction of O2- with halocarbons can be derived from ECD data obtained in the manner described here. © 1979, American Chemical Society. All rights reserved.