A HS-GC Question

[wulisheng2]

I ran a series (9) of reference stanards acrossing 100 times concentration range (40-4000ug/mL) on a HS-GC/FID. It was found that the 5 impurity peak areas remianed almost unchanged while the target peak aears increased reasonably proportional (R2=0.9995) with the concentration increasing in each level. Please help to explain why!

[Karen01]

I ran a series (9) of reference stanards acrossing 100 times concentration range (40-4000ug/mL) on a HS-GC/FID. It was found that the 5 impurity peak areas remianed almost unchanged while the target peak aears increased reasonably proportional (R2=0.9995) with the concentration increasing in each level. Please help to explain why!

Need more info... but a guess.... impurities are in the solvent you are using?

- Karen

[wulisheng2]

I ran a series (9) of reference stanards acrossing 100 times concentration range (40-4000ug/mL) on a HS-GC/FID. It was found that the 5 impurity peak areas remianed almost unchanged while the target peak aears increased reasonably proportional (R2=0.9995) with the concentration increasing in each level. Please help to explain why!

Need more info... but a guess.... impurities are in the solvent you are using?

- Karen

The HS solvent was purified water which was a "Blank" shot too. There was no any impurity peaks in this blank. Any other info would you need pls? Thanks!

[LindseyPyron]

If the system sits idle overnight with no runs, is your contamination higher on the first run of the day?

[chromatographer1]

Was the blank prepared at the same time as the standards? or at a different time.

The blank removes the possibility that the system produced the peaks.

My guess is the atmosphere or the vials were contaminated with the peaks you have found.

As I have seen 'pizza' peaks and 'aftershave' peaks in analyses I have performed, I am always amazed how sensitive HS analysis can be.

best wishes,

Rod

[wulisheng2]

If the system sits idle overnight with no runs, is your contamination higher on the first run of the day?

No, it was a consequtive run, there was no stop until the completion.

[wulisheng2]

Was the blank prepared at the same time as the standards? or at a different time.

The blank removes the possibility that the system produced the peaks.

My guess is the atmosphere or the vials were contaminated with the peaks you have found.

As I have seen 'pizza' peaks and 'aftershave' peaks in analyses I have performed, I am always amazed how sensitive HS analysis can be.

best wishes,

Rod

Very good questions and guesses. We are going to look into them.

BTW, what are the "pizza" and "aftershave" peaks please?

Tanks a lot!

[chromatographer1]

I did not run mass spec to identify the peaks conclusively.

volatile Oils in the pizza and fragrance components of the aftershave, small carbon number esters and aldehydes, were the most likely candidates.

Rod

ps clean baselines = clean chemist