Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Pesticide screening LC-QTOF, Agilent
Disposition • National Food Institute • EURL • NRL • Personale og udstyr • Kolibri • Agilent LC-QTOF • Bruker LC-QTOF • Background – pesticideanalysis • Number of pesticides • Quantitativeanalysis – LC-MS/MS • Pesticide screening • Construction of Library • Development of method
Pesticides • Pesticide manual: 1436 pesticides • Metabolites • Isomers • PCDL library of Agilent: 1664 pesticidesincluding relevant metabolites • Ourlibrary: 1716 pesticidesincluding relevant metabolites – retention times of around 1/3 of these
Pesticide screening QuEChERS Q-TOF Full scan - m/z = 50-1000 In positive and negative mode UPLC-method Eluent A: 0.1% formicacid + 5 mMammonia in water Eluent B: 0.1% formicacid in acetonitrile Analysis time: 20 min
QTOF-analysis – MS scan • Used to determine retention time No selection No collision
QTOF-analysis – Targeted MS/MS • Obtainingcompoundspectra for Library • Spectra of daughter ions from the single ion isolated in the quadropole Selection of single mass Collision 10, 20 and 40 V
QTOF-analysis – MS scan with collision • Screening samples • Spectra of daughter ions of all compoundseluting on a certain time point No selection Collision 10, 20 and 40 V
Spectra – MSscanincl. collision Ofurace, [M+H]+ 0V 10V 20V 40V
Qualitative versus Quantitative • Automated MS-based methods using accurate mass instruments suchToFs • Bioassays– nowseldomused
Validation – screening method Requirement: Confidencein detection/identification of an analyte at a certain concentration has to be established • Need to establish the lowest level of an analytecan be detected in 95% of samples (false negative rate of 5% is acceptable) • No requirements with regard to linearity or recovery • Exclude false positive results by analysingunspiked(‘blank’) samples.
Validation – screening method • Analyse 20 different samples for eachcommoditygroupspiked at the anticipated screening reporinglevel (SRL) • Samples should cover multiple matrices from the commodity with a minimum of 2 samples per matrix group. • Once applied routinely, on-going QC data shouldbeacquired. • For any new analyte further validation is required in order to be able to specify the Screening Detection Limit (SDL)
Considerations of validationsetup • How manydifferent samples? • Can wemake 2 samples of oneapple? • Or do weneed to purchasetwoapples? • We have a wish to validate at 3 levels • This is many samples to clean up • Can wethenspikeafterClean up? • No control of recovery!
Alternative validation plan 20 blank samples arecleaned up a b t , … 20 samples spiked at 0.10 mg/kg arecleaned up A B , … T The spiked samples arethendiluted with the blank samples
Thankyou for your attention