# Why there is no need for reference standards in High Resolution Mass Spectrometry (HRMS)

I have a question about HRMS (High Resolution Mass spectrometry). HRMS is a powerful technique that can discriminate between possible target compounds without the need of reference standards, unlike QqQ (triple quad systems). My question is simple why do HRMS don't need reference standards for analysis?

A short explanation would really help I cannot find the answer online or anything related to it.

Thank you, hopefully I can be helped with this part. I put a section of a book as an attachment maybe that will help.

Greets, Student

• I smell a rat. I've never work with an instrument that didn't use some sort of standard for setting it up. I can believe that you don't need to run standards with each particular sample, but never run a standard? No way. – MaxW Apr 29 '20 at 15:44
• I assume that the quoted text is about a GC-MS or LC-MS setup. With a low res MS you'd need retention time and MS to identify a compound. With a high res MS you just need LC or GC to give a clean separation then the MS alone could identify the compound. However the MS itself would definitely need standards to tune it. Say injecting a pure compound of some sort. – MaxW Apr 29 '20 at 15:55

$$^{13}$$CH$$_3$$CN, and the other analyte is CH$$_3^{13}$$CN, HRMS will give the identical molecular mass to five decimal places. One might look up their fragmentation pattern but MS is not that great at low masses (high noise). Here you would need another spectroscopic technique such as microwave rotational spectroscopy. These techniques are used an in emerging field called position specific isotopic analysis.
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