Abstract: In mass spectrometry significant error is introduced during sample preparation (sample-to-sample error), during ion generation (ion suppression), and during ion transmission (ion transmission losses). We demonstrate the ability to correct for ion suppression and ion transmission losses, and that once corrected for ion losses, a sample-to-sample normalization of the analytical sample to the internal standard is possible. By normalizing to a standard sample the analytical sample becomes completely comparable to any similarly treated sample.

Abstract: A method for identifying a biological analyte that is affected by a stressor is disclosed in which two substantially identical biological samples are provided, with a first sample being a control sample and a second sample being an experimental sample. The control sample is grown with a nutrient having an isotope of a first atom, whereas the experimental sample is grown with a nutrient having a second isotope of the first atom. The experimental sample is grown with a stressing agent and regimen. The samples are admixed, and the formed composite is mass spectroscopically assayed for analyte peaks. The ratio of first isotope to second isotope is determined for the peaks, as is a sample median isotopic ratio. The ratio for assayed analyte peaks is compared with the median ratio. An analyte whose isotopic ratio significantly deviates from the median ratio is an analyte affected by the stressing agent.