Accurate Mass Measurement

For decades, scientists have asked for HRMS analyses from mass spectroscopists.

Stop and think about this. What are they really asking for?

  1. HRMS = High Resolution Mass Spectrometry
  2. As in any analytical technique, resolution is an instrument property, not an experiment or analysis.
  3. High resolution allows separation of signals that are close together. If no signals are close, high resolution is not needed and does nothing for you. If you have a clean sample, there will never be a difference between a LRMS and an HRMS!!!

So why ask for HRMS?

Some how this abbreviation came to be wrongly associated with an experiment. It’s long past time to correct the error. Unfortunately, even mass spectroscopists have used the wrong expression because it’s habit. I have tried to make them aware of that issue.

(R.W. Kondrat, “High Resolution Mass Spectrometry”, J. Am. Soc. Mass Spectrom., 1999, 10, 661)

Correct Terminology

It is likely that what you really want is an elemental composition for your compound. If so, by itself HRMS CAN NOT do this. What needs to be done is an experiment where the mass of an ion is accurately measured. HRMS DOES NOT do this. Only by adding a calibration compound to the instrument can we get an accurate mass measurement. Once we have that, the elemental formula is obtained.

Therefore, if you want elemental formula you need to use the correct term.

“I need an accurate mass measurement for my sample.”

So when you submit samples and want elemental composition, ask for an Accurate Mass Measurement.


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