Halogen detection mode

The best sensitivity for 1,2-dibromoethane quantification is obtained by either electron capture detector (ECD) or Hall electrolytic conductivity detector (HECD) in the halide detection mode, since these detectors are relatively insensitive to nonhalogenated species and very sensitive to halogenated species. Another common detection device is a mass spectrometer (MS) connected to a GC. The GC/MS combination provides unequivocal identification of 1,2-dibromoethane in samples containing multiple components having similar GC elution characteristics (see Table 6-2). To date, GC equipped with either ECD or HECD has provided the greatest sensitivity for detecting... 

There are three principal detection modes in commercial detectors halogen mode to detect HX, sulfur mode for delecting SO2 or SO3, and nitrogen mode for detecting NH3. The detector response depends on the reaction conditions, the solvent, the pH, and the use of a postreaction scrubber. A schematic representation of a commercially available detector unit is shown in Figure 6.28. 

Fig. 2.6.18. LC-MS-MS analysis of halogenated alkylphenolic compounds in chlorinated river water (the Llobregat river, Spain). MRM mode (a) 253 —> 167 for detection of 35C1 nonylphenolic compounds (b) 297 — 79 for 79BrNP (c) 355 —> 297 for 79BrNPE C (d) 399 — 297 for 79BrNPE2C. Reprinted with permission from Ref. [39] 2002 American...

In the FTID mode, the detector is specific for nitrogen- and halogen-containing compounds, with limits of detection to about 1 ng. By operating the detector with air only as the detector gas, the detector response to halogens are increased compared to FTID and weak response to nitrogen... 

In the halogen mode, the alkali scrubber is removed from the outlet end of the nickel tube, and the electrolyte solvent is -propanol. The conductivity due to H of the HX is detected. The ionization of the other reaction products are suppressed by the w-propanol electrolyte. 

---