Traditional triple quadrupole mass spectrometry techniques are very capable of analyzing compounds with high sensitivity, but high resolution accurate mass spectrometry techniques are useful when the target analyte list is not well established (i.e. non-target acquisition). Further, non-target acquisition allows for the retrospective mining of previous data to investigate “novel” compounds. SWATH™ acquisition is a non-target analysis technique that obtains MS/MS product scans on all precursor ions and the product scans can be compared to established MS/MS libraries for compounds identification or confirmation. In contrast, MRM-HR may be a more sensitive acquisition technique due to the ability to use optimized collision energies.  Samples were analyzed using the SCIEX Exion LC system that was coupled to the X500R QTOF High Resolution Accurate Mass Spectrometer. A simple SWATH™ acquisition method was built spanning precursor masses from 100-1000 Da. The TOFMSMS scans were divided into 16 windows of varying size with narrow windows to minimize the MS/MS pattern complexity. The total cycle time was 1.0 sec which ensured sufficient data points across the peak and strong MS/MS for library matching. During data processing a target XIC components list of 275 compounds was prepared and retention times were verified by comparison to an authentic standard. MS/MS patterns were compared to the SCIEX HR pesticide library and NIST MS/MS library. In addition, a scheduled MRM-HR method was built.  The SWATH™ acquisition technique allowed for the unbiased analysis of the 275 pesticide compounds while simultaneously collecting MS/MS scans for compound confirmation. Quantitation was performed on the TOFMS precursor ion, or MS/MS fragment ion. For example, analysis of imidacloprid in raisin extract showed that the fragment XIC has a “clean” background, as compared to the TOFMS XIC, and thus uncompromised quantitation. The MS/MS library matching showed that the NIST library contained an additional ~20 compounds that were not present in the SCIEX HR Pesticide library. The scheduled MRM-HR acquisition method could be advantageous when higher levels of sensitivity are required. Finally, the two developed acquisition techniques were applied to the analysis of 8 fruit & vegetable extracts. The methods were capable to identifying a range of pesticides, including several at levels &lt;10 ng/g.

Comprehensive pesticide analysis by SWATH® and MRM-HR acquisition using the SCIEX X500R QTOF high resolution accurate mass spectrometer

256th National Meeting (2018)

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