3/27/2008 · I have a splitless liquid injection (organic solvent) that looks at a variety of peaks including internal standard. My GC system sat inactive and untouched for two weeks (still hot with FID lit). Upon reusing system, I found that the compounds with the longer retention times would not show up until several runs had been repeated.
1/15/2018 · GC compounds – poor peak shapes and missing peaks . … If so, when and on which instrument make/model? Is the current GC similarly equipped to the previous model? Q3. Is this a new analysis for this lab? If so, what method is being followed? Is it a common, well-publicized method like those from EPA, ASTM, USP, NIOSH, etc.
or is it an …
If the later eluting peaks have disappeared (or their response has decreased), you may want to review my previous post. When High Boilers Disappear (GC) Case 3: Only certain peaks throughout the chromatogram tail. This is usually caused by activity issues in the system, or inadequate instrument sensitivity for particular compounds.
When High Boilers Disappear (GC ) January 28th, 2013 by Alan Sensue. Were you ever trying to analyze high boiling point compounds (using GC) when they either disappeared , or their response severely decreased, while at the same time compound response for lower boiling point compounds looked fine? Well, it has happened to most of us at one time or …
Using GC-FID an unknown peak consistently appears in our reactions. The blank shows no peak other than the solvent peak (CHCl3). Using the same sample, column and GC parameters on a GCMS the peak …
6/25/2010 · The latest problem with this instrument is the weird dopamine peak that comes and goes. I injected dopamine standards and managed to see a peak that seemed to be dopamine (retention time around 10 min). Shape of the peak was good. However, when injected again after some time (10-20 min) the peak had vanished.
peaks or erratic baseline). 1. Leave the GC between 40 to 50 °C for 8 or more hours. 2. Run a blank analysis (i.e.
start the GC, but with no injection) using the normal temperature conditions and instrument settings. 3. Collect the chromatogram for this blank run. 4. Immediately repeat the blank run when the first one is completed.
If the ghost peaks disappear while in the split mode, then the split vent line and/or trap are likely the problem, and both should be replaced. (Example of a split vent trap shown below.) I hope something here has helped you identify and fix the source of your ghost peaks.
Broad Peaks Solutions • Minimize dead volume in the GC system; verify proper column installation, proper connectors, proper liners, etc. • Verify injector and detector •ow rates and adjust if needed. • Verify make-up gas •ow and adjust if needed. • Increase GC oven programming rate. • …
