Contaminants in GCMS
Contamination is often detected by observing unusually high background signals in the mass spectra. This contamination can originate from either the GC or the MS. Analyzing the specific contaminants makes it possible to trace the source of the contaminants. Certain types of contaminants are more commonly associated with the GC, whilst others are typically linked to the MS.
Sources of contamination in GC:
- Dirty liner
- Septum bleed
- Contaminated syringe
- Poor quality carrier gas
- Column bleed
- Contamination due to incorrect handling of cleaned parts
Sources of contamination in MS:
- Air/water leaks
- Contamination due to incorrect handling of cleaned parts
- Dirty source
- Solvents from cleaning the parts
Figure 1. SCION Instruments 8300 & 8500-GC with the 8700 SQ-MS and 8400PRO Autosampler.
Common Contamination Ions
Table 1 Common contaminants in GCMS with associated ions
How can the contamination be resolved?
Air/water leaks → Tighten the nuts on the transferline side, tighten the nuts on the injector side, replace Vespel ferrules, bakeout MS and GC.
Cleaning solvents → Bake out the system and if issue persists then clean the source
Tuning compound ions → Clean the source, replace the tune solution.
Septum bleed → Replace the septum
Column bleed → Cut the column and reinstall, if issues persist then condition the column. If still ongoing problem then consider replacing the column.
Damaged O-rings → Replace the O-ring.