By StephenLHardy on Friday, October 29, 1999 - 05:24 pm:
I am getting a negative peak immediately after the mineral oil peak. It is interfering with my integration. I am using DCM for my carrier solvent and I am using an infrared detector. This occurs even when I inject a blank sample. The mineral oil comes out at 16 minutes and the mineral oil peak does not return to baseline but goes immediately into a negative peak. What is causing this negative peak? I would appreciate any help you can give me. I have been trying to get this method working for 16 months.My supervisor is getting impatient. Help!
By hinsbarlab on Tuesday, November 2, 1999 - 09:12 am:
What is the solvent the mineral oil is diluted in? What is your injection volume? What size and type of column? DCM = dichloromethane? What approaches have you tried to corrrect the problem already?
By David Grant on Wednesday, November 24, 1999 - 07:51 am:
I have found that known analyte peaks are followed in some samples by a smallish neg peak, about 1/4 the size of the analyte peak. This happens about 5% of the time, sometimes to one of a series of replicates, sometimes to all. It seems sample specific, in other words, it does not happen to all the work done in a given morning. It fits no obvious pattern.
By anonymous on Wednesday, November 24, 1999 - 01:56 pm:
have you considered that the blending of your analyte with eluent (the tail) might cause a gradient with a lower IR absorbance than pure eluent (DCM). perhaps a change in eluent is called for?
By ac on Tuesday, December 7, 1999 - 07:09 am:
Changing the brand/supplier for DCM may help.
Posting is currently disabled in this topic. Contact your discussion moderator for more information.