PBDE surrogate factor/ calculation issues


I have successfully used surrogate calculations for masshunter with other methods (recoveries of surrogates against internal standards).

This method I created seems to be glitching every so oftten. The standards appear to form a nice calibration using average of response factors, include origin, no weight. Sometimes when I calculate samples though, it multiplies by 2 for some reason leaving my surrogates 1/2 of what they should be. There is almost a hidden 2x factor. 

Unlike my other method, these surrogates and internals are at different concentrations but the surrogate concentration is the same as the internal. Additionally, this only happens with half the surrogates, the middle ones. 

Any explanation?

I have attached some photos.

The one shows how my one qc, same level as my standard 3 is doubling. Calculating the recovery based on response factor has it at approc 74%, 2x what it is displaying. The surrogate and internals all match according to table. 

Also attached is one of the surrogates that is working.

  • Hello  ,

    Since the relative concentration for your QC is showing as different from the standards it is possible that the method has become corrupted or concentration values in the method were changed but the batch was not fully analyzed. If you edited this method from a previous method you should check the ISTD conc settings in both the ISTD setup section and in the concentration setup section, as it is possible these can be different. In current versions of quant it is also possible to specify different ISTD concentrations for each standard, which could also cause what you are observing.

    If verifying these settings does not resolve the issue then it would be best to make a new method from acquired MRM data to make certain that there are no issues with your calibration table.

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