Hello - I am using GC Autosystem (Perkin Elmer) and my ref gas for N2O appears to show a slight double-peak in the reference gas (0.5ppm N2O standard). Additional samples i run (including ambient air, closed chamber samples) show single peaks of N2O. Flow rates all look ok, and have checked column, temps, septa, all look ok too. If the ref gas shows the same consistent peak with repeated use, is it still possible to calibrate using this gas and ambient air injections to monitor changes with time? the baseline value appears low and does not change, and i get clear separation of peaks also. Thanks
By Anonymous on Thursday, December 11, 2003 - 12:32 pm:
It would appear your reference gas is contaminated. You should confer with your supplier on getting a replacement. Is your instrument integrating two separate peaks in your reference sample? If so, and you are sure which one is N2O, they maybe you could use it if you absolutely had to, however, the best possible scenario would be to have a clean standard.
By Anonymous on Friday, December 12, 2003 - 08:59 am:
We have seen contaminated reference gas for N2O analysis. This is from a reputable supplier, not a little fly by night operation. They have since changed the process and we do not see the extra peak any more. The key is that you do not see the peak doubling for air or other samples, which is exactly our experience. Call the supplier of the gas and explain the problem and ask to have the gas replaced with a standard from a different lot. We suspected the contaminant in our standard was a Freon, but were not able to confirm this.
By di on Monday, December 15, 2003 - 03:54 pm:
thanks alot, i appreciate your help.