Troubleshooting and Error Messages
User Information 171
Carryover in air or solvent blanks
In theory a run containing a blank made after a run with a
sample has no peaks in the chromatogram except for the
analytes from the lab air or solvent that is trapped in the sample
vial. Carryover results when sample condenses on the flow path
or is trapped in unswept area from a sample injection. Run a
blank to see small quantities of these analytes.
If the amount of carryover in a series of solvent blanks
decreases by a factor of 5 to 10 for each run, the carryover is
probably due to an unswept area. Check the following:
• There is flow from the GC inlet to sweep the inlet weldment.
• Check the transfer line connection to the GC inlet.
If the amount of carryover in a series of solvent blanks does not
decay for each run, the carryover is probably due to analytes
adsorbed or condensed on the flow path or in the inlet. Check
the following:
• Poor choice of heated zone temperature settings. See page 52.
• Poor choice of vial pressurization pressure or time.
See page 57.
• Flow path or GC inlet contamination.
• Poor choice of inlet.
medium_standard.book Page 171 Tuesday, February 17, 2004 10:14 AM
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