I'm hoping someone can help me understand the library match factors from Quant MH B.08. The attached pdf shows 3 examples. In the first example, the match factor or match score of 89 makes sense to me. Most of the masses are present and there are no extra masses in the unknown spectrum (top). The middle overlay shows a match of 41.5. This doesn't look right to me as only 1 of 4-6 major masses is present, but it is one of the library masses. The last example really has me wondering what is going on. I agree the unknown spectrum is only one mass but the match of 30 is strange. None of the library masses are present. I'm open to ideas. Thank you.
Hi Trifecta,
On the surface the last example is in enigma but I think that I may know the answer. My theory is that the sample spectra actually has some very, very small ions that we don't see due to scaling issues. One or more of the ions align with the library spectrum and we get a non zero LMS. I don't have the data to test this but if you will expand the y-axis you can check for this.
Tom