Confirmation of pesticides in jalapeno peppers using QTRAP® System MS/MS data and library matching in SCIEX OS-Q Software
Combining enhanced product ion scan with the latest software for high confidence confirmation
KC Hyland
SCIEX, USA
What: Food testing labs are frequently confronted with the need for more confirmatory information when it comes to analyte identification in real- world samples. In complex matrices, interferences may complicate interpretation of data resulting in false positives or reported residue levels to come into question. Combining QTRAP® System with the latest software tools of SCIEX OS-Q Software allows for the collection of full-scan MS/MS spectra for targeted pesticides in complex food samples. Those MS/MS data can be subsequently searched against SCIEX verified libraries for unambiguous qualitative confirmation of pesticide detection and ID.
How: The MS method was set up with a targeted MRM list of 200+ pesticides. IDA (Information Dependent Acquisition) criteria were defined such that Enhanced Product Ion (EPI) acquisition would be triggered when an MRM signal exceeded a threshold of 2000 cps. This type of data acquisition results in the collection of MS/MS spectral information in addition to the MRM signal (Fig. 1). Samples of dried, canned, and fresh jalapeno peppers were extracted and analyzed for the pesticide panel. Data were processed in SCIEX OS-Q Software for quantitation by MRM and spectral identification by library matching. Figure 2 shows collected MS/MS spectra being used to confirm the identity of the MRM peak in the pepper extract. This additional stringency in identity confirmation could help protect against reporting false positive detections for residues in complex samples.
Figure 1. The QTRAP® 4500 System with EPI scan type triggered from MRM signal from target pesticides. The resulting MS/MS spectra were matched to library spectra for confirmation.
Figure 2. High confidence in positive detection possible with QTRAP System and SCIEX OS-Q Software. ID and quantitation of pesticides can be achieved with high confidence using QTRAP System to collect MS/MS spectra in addition to MRM peaks. Retention time and MS/MS pattern are compelling evidence that the identified peak is Difenoconozole. Circles on the chromatographic peak represent where EPI scan has been triggered; the software automatically chooses which spectrum is the highest quality and displays it on the right. The colored circle denotes which scan is being displayed. SCIEX OS-Q Software results table quickly shows with green check marks in the Confidence columns where peaks have been confirmed with RT error <2% and library fit score of >80%. Rapid visual assessment of large sample sets is possible, ultimately resulting in greater efficiency and increased qualitative confidence in reported detections during data processing for residues in food samples.
