I'm just beginging to work on GC/ECD and got some ptoblems in identifying the origine of some pics. The problem first was that the base line was so flate and when doing some injections (even with the standard that is gamma-HCB 0.1 ng/Ál)i didn't get pics!
Then a technician came to fix it. Now i got high pics even when I inject hexane (I injected 2 types of hexane). There are two pics that appears regularly. I thought that it was a problem of contamination. Then, i cleaned the syringes, i conditionned the column(DB-608), the detector and the injectors. But i still got a pic.My question is: is it normal to get high pics when injectiong solvent? and how can we do with if we want to perform analysis?
Thank you in advance.
By Anonymous on Friday, May 14, 2004 - 12:27 pm:
Your ECD is now behaving properly. If you look at ECD specifications you will see a selectivity specification, such as lindane:hexane = 100,000 (made up numbers). This means to get a peak as large as the one produced by 10 pg of lindane you would have to inject 100,000 times as much hexane or 1,000,000 pg. So with a properly functioning ECD you will see your solvent peak, and potentially other non chlorinated compounds. Even a compound with very poor electron capture efficiency will give a peak if enough is injected.
It is important to remember the ECD is a selective detector, not a halogen specific detector.