Analyzing results from running the DB-5 Test Standard

I have several questions related to interpreting the results from injecting the DB-5 standard into my 7890B GC/5977B MS. 1.) are the 8 analytes supposed to elute in the order specified on the Certificate of Analysis? 2.) If they elute in a different order, is that meaningful in any way or does it indicate anything regarding the "health" of the column? 3.) Masshunter Qual didn't identify three of the 8 peaks. I manually integrated the 3 then did a NIST library search. The three compounds did elute, however the library search match for them was very low, < 30%. Is this meaningful at all? 4.) In the end, I'm not quite clear on what I'm supposed to glean from running the standard. I will admit, I'm running it after having used this particular column for some time. 5.) Is the goal of running the standard simply that I'm meant to compare changes to the peak intensities and locations with time? 6.) How do I harness the data to figure out if I need to trim the column or install a new one? PHEW! That's a lot of questions. Any help/guidance is appreciated. Thank you.

Parents Reply
  • How much do you cut off?  Hopefully at least five to ten inches or more. Do you recalibrate the column length in the GC settings in MassHunter when you cut it?  Application dependent, of course, but you may reduce that problem by changing some system parameters or doing better sample preparation.   Most operators rarely need to trim the head of their column more than once a quarter/every couple of months.

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