By Anonymous on Wednesday, January 29, 2003 - 03:50 pm:
1050 Agilent autosampler: anyone ever get a buildup of contaminants in the autosampler module which required rotor valve to be taken apart and ultrasonically cleaned? I'm getting ghost peaks of consistent retention times from CH3OH, also when I manually hit autosampler bypass/mainpass functions. I changed to a Tefzel rotor seal but that didn't help.
By Steve on Wednesday, January 29, 2003 - 06:35 pm:
Contamination may also be in the needle, seat and metering seal. If that still does not fix it, replace the sample loop. I have seen situations with carryover/ghost peaks that were removed by replacing the loop capillary.
Good luck.
By Anonymous on Friday, January 31, 2003 - 10:04 am:
We have found that the PEEK rotor seals are much better in combatting carryover problems. As suggested by Steve above, it could also be in another place. Does the peak area/height lessen over repeated injections? Does it stay the same? Try washing with a solvent which the sample or suspected contaminant is readily soluable in, also fill a vial and do some large injections at the same time.
By Anonymous #1 on Tuesday, February 4, 2003 - 12:29 pm:
OK, I got rid of the contamination; I may have cleaned "too much" but I wanted to get it usable. I ultrasonically cleaned the autosampler valve stator, stator ring, and isolation seal using water, then methanol, then ACN. I manually flushed out the lines in the autosampler with same using a 10 ml syringe with adapter. I used the Tefzel rotor seal and all was OK (where changing just to new Tefzel didn't help). I then ultrasonically cleaned the original Vespel rotor seal and re-installed it, and everything was OK there too. So I don't really know if manual flushing of the A/S lines, needle, etc., was necessary.