I am using Agilent Gc/MS and we sometimes have eclectic outage schedule. After that I make my standard again every time. and its value is getting higher every time. I use same conditions and dilation but for the 1st time value was 482295, then 2nd time 712293 and now its 1175216. I can not get reproducible data due to this problem. any suggestions please?
#Michael, actually that power outage is due to some maintenance work and its twice a year. I want to know the reason that why I am getting different result for calibration. i am using squalene for standard. so basically if I shoot same amount I should get same or nearly same peak area. but this is not the case. I want to get very reproducible data. So any experience about this?
What are your analytical conditions ?; squalene is towards the upper end of the range for routine GC, and can easily carry over from run to run, leading to progressive increases in peak areas.
Squalane is a better standard than squalene because it is more stable in solution. You need to reserve some of each standard so that you can re-inject it after a power cut to comapre the areas between reserved and freshly made standard. That will tell you whether you have a problem with the analysis or with the preparation of the standard.
Also when you re-tune the MS after an power cut its sensitivity is likely to change, if your samples and standards are run under the same conditions i.e. you alwys use an up to date calibration of quantity vs area, then this should not affect your results.
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