Browsing by Author "Virolainen, Taija"

Tiivistelmä/Referat – Abstract The literature part was focusing on the metabolism, use, safety and analytical methods for glyphosate (2-phosphonomethylamino) acetic acid. The focus was on methods that are used to analyze glyphosate in foods. Glyphosate is the active compound of an herbicide. The experimental part was done in the Customs laboratory. The main object was to develop a method to analyze glyphosate, aminomethylphosphonic acid (AMPA) and glufosinate in food without derivatization using UPLC-MS/MS technique. The EURL-SRM QuPPe method was used as a sample treatment for durum wheat, iceberg lettuce, orange and avocado. The separation was done using high performance liquid chromatography and detected in triple quadrupole mass spectrometer using electro-spray ionization (ESI-) and multiple reaction monitoring (MRM). Four analytical columns were evaluated: Acquity® UPLC BEH HILIC, HypercarbTM Porous Graphitic Carbon, HypercarbTM Porous Graphitic Carbon and ShodexTM HILICPak VT-50 2D connected to ShodexTM HILICPak VT-50G 2A precolumn. ShodexTM HILICPak column was chosen due to its superior retention of the compounds. The mobile phase contained water, 1 % formic acid in water and acetonitrile (70:20:10). The linearity of the method was 0.01–2.2 ng/ml for glyphosate and AMPA and 0.002–2.2 ng/ml for glufosinate. The high amount of matricecompounds that coeluted with AMPA made identifying and integrating the analyte difficult to do. The retention times of glyphosate and glufosinate were shifting more than the validationcriteria ± 0.1 minutes. Isotope labeled glyphosate (1,2-13C2 15-N-glyphosate) that was added to the samples had a similar shifting in retention times which made it possible to efficiently evaluate the validation of glyphosate. The lack of internal standard for glufosinate meant that the method could not be validated for glufosinate. The limit of quantification (LOQ) for glyphosate was 0.04 µg/ml with RSD < 20. The validated method was suitable for analysing glyphosate residues in food.