By Anonymous on Thursday, January 31, 2002 - 01:49 pm:
The MP is 100% H20 and the diluent of the sample is also H20. When I inject a H20 blank onto the system I get a negative dip at ~16 minutes, which is the same time that my peak of interest elutes. Also, when a zero volumne injection is done the negative dip is still present at ~16 minutes, intensity is the same as when a regular inejction is made. The column is a MetaCarb NaCa, 300 x 7.8. The same negative dips occur with various types of manufactured and filtered water sources. We have tried degassing and non-degassing the MP, and various vials and caps and the negative dip remains.
By Anonymous on Thursday, January 31, 2002 - 06:02 pm:
The zero volume injection is a big clue. This is not sample or solvent related related in any way. However, you could be seeing carryover material from the injection valve or , more likely, a pressure spike from the turning of that injector valve. RI detectors are quite sensitive to to pressure pulses. Did you try talking to Agilent tech support?
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