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I have a question regarding standards. Who has the most reliable ones at the least expensive price?
Thanks
Bear
Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.
Rndirk wrote:
Anyone have tips to share on the sample preparation for this method?Chromatography and MS wise, this method runs well. Nice peaks, good sensitivity, good calibration curves. We took precautions in terms of contamination and carry-over, no problems there so far.
However, in our first tests runs we have troubles with recovery (both spiked analytes and internal standards) for higher molecular weight compounds, especially the sulfonic acids. Recoveries are in the low % range for these compounds, while they're fine (60-100%) for the compounds that elute earlier.
Any particular tricks for the SPE protocol that we might be missing? Our calibration standards do not go through the procedure. With these recoveries, we're at the limits of sensitivity so we have to get it better before starting the validation.
Rndirk wrote:
Thanks James.
Our samples are in polypropylene recipients. I'm not sure if that makes them stick more or less compared to glass.
What you describe was actually tested yesterday. I was hoping that this would fix the problem but unfortunately there's no significant different in recovery...
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