Shimadzu has produced an application note describing a process for applying ‘MRM Spectrum Mode’ and library searching for enhanced reporting confidence in routine pesticide residue analysis.
Introduction
In a regulated environment such as food safety there is a growing need to enhance the capability in routine monitoring programs by increasing the number of pesticides measured in a single analysis and at the same time delivering the highest confidence in compound identification to reduce false detect reporting. To this end, routine multiple-reaction monitoring (MRM) methods have been extended to monitor a higher number of fragment ion transitions to enhance specificity and reporting confidence. For each target pesticide, responses of multiple fragment ion transitions were assembled and displayed as spectra, which could be used in routine library searching and compound verification using reference library match scores.
Method
Described in this article is an example of this ‘MRM Spectrum Mode’ being applied to quantify and identify, in spiked food matrix, 193 pesticides using 1,291 MRM transitions. The advantage of this technique is that library searchable product ion spectrum data is used in target compound identification without compromising sensitivity, accuracy and robustness in quantitative data reporting. As the method involves no “triggering”, it is robust and the data produced is consistent regardless of coexisting pesticide residues.
Conclusion
False positive results are a major issue for all pesticide residue monitoring laboratories. EU regulations require that retention time and the ion ratio between 2 MRM transitions are within a set threshold. However, even applying this criteria false positives may occur for certain pesticide/commodity combinations. In this application paper, MRM Spectrum Mode is applied to identify and quantify 193 target pesticides in a
number of different sample matrices. The library score is used as an additional identification criterion in order to improve identification confidence.
By downloading this application note you will learn:
- about the potential of triple quadrupole instrumentation – not just quantitation but also identification at high sensitivity.
