Chromatography Forum

I have a strange problem that has started occuring in the last few weeks. I am running EPA8260B using purge and trap and 6890/5973 agilent GC/MS.

I will run my ical for all my compounds in a mix and have an ical for acetone from 4ppb to 300ppb. It will sometimes work on average response <15%, but usually have to have a linear plot ~0.995.
The next day using the same standards or new standards (I have tried both ways - my acetone will only be around 50% recovery). It can't be a standard problem since I use a stock containing all ketones and all the others look great.

Any suggestions or answers would be appreciated.

Acetone can definitely be problematic as it is a regular lab contaminant.

What level are you running your CCV at?

I find that anything below 10ppb causes problems with the initial calibration simply because of the acetone in the background from the lab air. If your CCV is at 50ppb and during the initial curve the background was above 5ppb that will throw you off several percentages if the background level is gone the next day. Does your blank from the second day quant to a negative concentration for Acetone when you use the linear fit instead of average response factor?

Are you using a vial autosampler for the purge and trap or just hand injecting into the sparge tube?

I was consulting with a lab once that had a similar problem with 2-Butanone, when I visited the lab the first day everything seemed ok. The second day was much warmer and when I arrived they had an open window near the GC/MS. I noticed that I smelled paint and asked what the building was next door. Turns out it was an office furniture company and the 2-Butanone contamination they were getting was from opening the window and letting in the paint fumes from the company next door.