Chromatographic Troubleshooting
Peak symptoms
stationary phase with trace levels of O1, H1O, and/or other materials present in the carrier gas.
CA contaminated inlet may also produce ghost peaks. Residues in the inlet are volatilized or pyrolyzed and swept onto the head of the column. Try reducing inlet temperature; if this eliminates or reduces ghosts, the inlet should be cleaned.
2.Additional peaks appear when pure sample is injected:
CThese might be ghost peaks as described above. Make a blank run; if the peaks persist, they are not sample related.
CA common cause of extra peaks, assuming the sample is pure, is degradation of one or more components by an overheated inlet. Test this by reducing inlet temperature.
Operate the inlet at as low a temperature as possible without causing peak broadening due to slow vaporization. Also, perhaps a more volatile solvent can be used. In extreme cases, derivatize the sample before analysis.
CMetal columns may also degrade the sample. Extra peaks in this case are usually broader than their immediate neighbors since they are generated along the entire length of the column. If this is the cause, changing to an all•glasssystem may be necessary.
210