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Mass spectra of rider peaks

JamesP

I'm not sure if this is right place to pose questions of this nature but here it goes.  

When trying to obtain the mass spectrum from a smaller peak on the slope of the matrix peak what is the best approach? How much does subtracting the matrix peak from the rider peak impact the accuracy of the mass spectrum of the rider peak? I attached an example TIC from my current analysis. My thought is that some mass fragment ions may be inaccurately represented in the rider peak due to the matrix peak. Is it better to subtract from baseline outside of the matrix peak? Thanks in advance.

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  • 0

    If you are trying to get a perfect spectrum of a peak to help with unknown identification or higher library search match quality, it is best to work towards peak separation chromatographically.  Why is your matrix so huge and tailing into your peaks of interest?  All that matrix is contaminating the system and, since the filament is on while it is still eluting it is reducing the filament lifetime, too. Is there any way to remove or reduce the amount of matrix?  Or can you work with your GC parameters to separate the peaks of interest from the giant peak? 

    Your success at subtracting the matrix from the peak of interest on the tail depends on the peaks themselves. If they share many ions it is tough.   Do you have a sample without the small peaks in it for direct comparison?

    What are you trying to achieve?   It doesn't really matter if the peak is well defined chromatographically, you know what it is by injecting known standards, and you are quantitating it.

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  • 0

    If you are trying to get a perfect spectrum of a peak to help with unknown identification or higher library search match quality, it is best to work towards peak separation chromatographically.  Why is your matrix so huge and tailing into your peaks of interest?  All that matrix is contaminating the system and, since the filament is on while it is still eluting it is reducing the filament lifetime, too. Is there any way to remove or reduce the amount of matrix?  Or can you work with your GC parameters to separate the peaks of interest from the giant peak? 

    Your success at subtracting the matrix from the peak of interest on the tail depends on the peaks themselves. If they share many ions it is tough.   Do you have a sample without the small peaks in it for direct comparison?

    What are you trying to achieve?   It doesn't really matter if the peak is well defined chromatographically, you know what it is by injecting known standards, and you are quantitating it.

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  • 0 in reply to paulsalverda

    It's set at a split ratio of 75:1,  I could go higher but risk missing some of the smaller peaks.  We are doing a fingerprint analysis for a potential customer for this gas (HFP) so identifying the unknowns is the goal.  I did think about adjusting the method to try to get the smaller peaks to elute further down the tail.  I just started though and still doing test runs.  

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