Re: Do surfactants affect Purge & Trap recovery
Posted: Fri May 11, 2018 7:07 pm
What I don't get is how you can do a respone factor calibration with a bottom value that is that noisy without ruining the whole curve.
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I have BFB and the other surrogates in my internal standard mix (allowed for 8260). With optimization, I was able to get BFB separated 0.05 min from isopropyl benzene on a 20m x 0.18mm x 1um DB-VRX column. So, I can do a tune check on my 40 ppb CCV.James_Ball wrote:Bigbear wrote:
I looked at .3, but was not impressed with all the QC requirements. Matrix spikes again?? Did enough in the past to see that drinking water matrices had no affect on VOC's.
MS/MSD has not given me problems with .3 but having to analyze the low CCC immediately after the calibration and hit +/-50% can be tight and also doing the MRL test. Once you do get the system to run those two checks though, you are confident that you are actually reporting true non-detects and that hits just above the MRL are accurate. I don't like going to CCV every 10 samples instead of 12 hours, but you don't have to check the tune unless you recalibrate so that saves you one injection at the start of each day, though I normally run one just to wake the instrument up.
I called Valco and resurfacing the valve is pretty reasonable. A new valve is $600 but resurfacing is $165. Is your valve sticking or is it the valve rotator? might be time to investigate getting a new switcher. Although, with that low a frequency, and volatiles seem to be robust enough to be restarted the next morning; maybe its not worth the trouble.James_Ball wrote:
I have one older Evolution that the 6 port valve will stick about once a month. Gives a front inlet shutdown error because it blocks the flow long enough to shut it down. When we are lucky it happens on the tune shot and stops the run at a very good position, other times it stops it just after the CCV