High Percent RSD for vinyl chloride

[nicmendola]

Trying to resolve problem with vinyl chloride failing % RSD. Response factors decreasing with increased concentration. Any ideas?

[tkubowicz]

Hello

You didn't write anything about method:
-parameters for GC
-sampling technique - Purge and trap?

More details you give, quicker answer you'll get

Regards

Tomasz Kubowicz

[dblux_]

Trying to resolve problem with vinyl chloride failing % RSD. Response factors decreasing with increased concentration. Any ideas?

What is your main problem, RSD or response factors ?
Relevant details neccessary if you want anybody to devote time for your problem.

[nicmendola]

The main problem appears to be the decreasing response factors which is causing the %RSD failure. We are getting linear curves for all gases, except for vinyl chloride. The responses for vinyl chloride are linear for the first 3 calibration points and then start declining from the midpoint to the highest level.

[nicmendola]

Sorry for lack of details. I will post them next. Thanks.

[nicmendola]

Running Purge & Trap Tekmar ATOMX autosampler, 5mL purge volume, 11 min purge time and Supelco "K" trap VOCARB 3000. Agilent 7890B GC and 5977A MS with Agilent J&W DB-VRX 20m x 0.180mm x 1.0um column. 50:1 split ratio, Calibration range 5 to 200.

[dblux_]

EPA 524 method accepts quadratic regression. Will this help to get acceptable RSD for vinyl chloride ?

[Bigbear]

Using the 6mm draw out plate? BFB_Autotune? Dry purge?

You should consider upping the split to 150:1.