By Anonymous on Thursday, June 3, 2004 - 01:24 am:
We have Waters W2420 ELSD detector. We have just started with ELSD detection and faced with various problems, I suppose common for this detection technique. So, we are obtainig ghost peaks after the main one on different samples known to be pure. These peaks are irreproduceable and can be eliminated by applying maximum (60 psi) nebulizing gas pressure, which causes decrease in sensitivity. Did anabody have experienced such a problem or have any useful idea about it. And I will be glad to know where can I find literature on ELSD detection. Thanks for any answer.
Regards, Valentine.
By Anonymous on Thursday, June 3, 2004 - 10:45 am:
It's very important that your inlet gas is total pure, and supplied with an oilfilter. If you got oil in the system, you have to clean the hole system, bad luck!
By Anonymous on Saturday, June 5, 2004 - 11:31 pm:
I am using Nitrogen from Nitrogen generator which is simultaneously used by LC-MS system, so I am pretty sure that the gas is of sufficent purity. The ghost peaks are not present in blank chromatograms and appear in more or less the same region after the main peak, however neighter their quantity nor their area % is reproduceable. This is not a question of the specific chemistry of my compound as I obtain the same result with different compounds. Its pretty clear for me that the peak is being splitted somewhere in ELSD detector or before. I'l be glad to hear any useful idea how to eliminate this problem without applying maximum nebulizing gas pressure. Still waiting for answeres, Valentine.
By Roeland on Monday, June 7, 2004 - 07:15 am:
Which solvents are you using? I had enormous problems with chloroform/methanol and acetic acid.
Do you use gradient elution?
By Anonymous on Monday, June 7, 2004 - 09:56 am:
To Roeland.
I'm using Acetonitrile / Water / TFA. Isocratic elution. What kind of problem did you have?
Valentine.
By Thomas on Monday, June 7, 2004 - 11:31 pm:
To Valentine
Sorry, I know this is off-topic, but I would like to know which LC/MS system and which N2-generator you have. We have HP1100 LC/MS with a N2-generator, and are right now considering if the N2-generator has the capability to supply our new ELSD with N2.
Best Regards
By roeland on Monday, June 14, 2004 - 06:46 am:
Just some peaks that came of during increase of polarity during normal phase separation; i solved the problem by swithing onto formic acid as modifier.
Do the peaks occur in a blanc injection?
By henrik on Wednesday, June 16, 2004 - 12:42 pm: