Mass resolution establishing

Evidence for fluorenone (12) as a minor product of the pyrolysis (a small peak at mass 180 that persisted at reduced ionizing voltage) was indeed found. Direct-coupled gas chromatography-mass spectrometry clearly identified a minor component as fluorenone and a precise mass-measurement on a high-resolution mass spectrometer established C13H80+ as the empirical formula of the major component of nominal mass 180. 

We have since verified that there has been no noticeable loss of mass resolution or sensitivity for the Esquire 3000+ using a modified ring electrode that has 2x1.5 mm laser holes and a single 2 mm fluorescence hole. Mass calibration and tuning the phase between the drive frequency and the auxiliary AC were necessary to re-establish ion trap performance. Our experimental peak width (both with and without ring electrode holes) is about 0.3 Th for rhodamine 101, or about half that of the simulation. Possible reasons for this discrepancy include inaccuracies in the shapes of the model electrodes, insufficient cooling time in the model prior to ion ejection (only ca 2 ms was used to shorten the length of the simulation), or an incomplete description of the ion ejection waveform. 

However, it should be noted that the identification and quantification of phenolic compounds using low- and high-mass resolution is not normalized in food analysis, and therefore guidelines for the development and validation of analytical methodologies should be established for the analysis of phenolic compounds in vegetal matrices, as the SANCO guidelines do for pesticides in food and feed. 

Generally, high-resolution mass spectrometry (HR-MS) aims to achieve both high mass resolution and high mass accuracy. These quantities have been introduced without considering the means by which they can be measured. The key to this problem is mass calibration. Resolution alone can separate ions with m/z in close proximity, but it does not automatically reveal where on the m/z axis the respective signals are located. This section deals with the techniques for establishing accurate mass data and their analytical evaluation [32,33]. 

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