Table 2.

Troubleshooting guide for SCFA detection with GC-MS.

Problem	Possible Cause(s)	Solution
Vacuum pressure is consistently higher than that recommended for flow rate	Air leaks or other vacuum problems	Consult operation manual
Spurious chromatogram peaks and poor repeatability	Backflash in response to flooding the injection line	Inject less sample volume
	Poor recovery of analyte from sample	Ensure that freeze/thaw cycles have been kept to ≤ 2 and that samples are stored at −80 °C for long-term storage
Shifting retention, baseline disturbances	Column bleed, column contamination, column aging	Replace with new column and condition before use