What are meant by the terms mass precision, mass measurement accuracy and mass resolution?
Mass precision is a measure of how good the instrument you are using is at measuring a mass. This is physical limit of the design of the instrument and/or experiment you are performing and cannot be corrected for by altering (improving) the calibration of the instrument. This is a fixed experimental error and it is good science to quote it with mass data (although most people don’t do this). For example: Consider a particular instrument set up in a particular way which might have a quoted mass precision of +/- 0.0001 Da. This would mean that if you measured the parent ion of phenol as 94.0419 Da this would actually have a measured mass of 94.0419 +/- 0.0001 Da. A better way to express this error or uncertainty is 94.0419(1) Da. Mass measurement accuracy is the observed difference between the experimentally measured mass and the theoretical mass of a particular ion. To obtain a good statistical error, it is good science to make measurement repetitions (5 times or more is good), although
