By rvjayanthi on Tuesday, July 4, 2000 - 03:52 am:
Please let me know why there is a peak of hexane when a pesticide residue solution is analysed by ECD,considering Hexane is not ECD-active
By H.Schnorbus on Tuesday, July 4, 2000 - 07:32 am:
That's simple enough. There is obviously a not separated ECD-active compound in your hexane peak. Make a test with hexane out of a new bottle.
By Ron on Wednesday, July 5, 2000 - 07:46 am:
The peak from hexane is normal. Hexane is much less sensitive than a chlorinated compound, but there is an ECD response to hydrocarbons at high levels. In the specifications for your ECD there should be a selectivity specification, which will show the relative sensitivity of a chlorinated compound and a hydrocarbon. For example, if the selectivity was lindane/iso-octane = 10e6, then 1 ppm would give the same response as 1,000,000 ppm (pure) iso-octane. If there was no response to hydrocarbons, the selectivity would be infinite.
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