Browsing by Author "Saukko, Jaana"

Pesticides are used in primary production to protect and strengthen the crops. Many of these pesticides can be analysed with multiresidue analyses, but some of them need a single residue method (SRM). Polar pesticides are an example of these compounds. Because polar pesticides, such as mepiquat, chlormequat and ethephon, have strong polar interaction, small concentration and weak volatility their analysis from vegetable samples is challenging. The target of the literature part of this thesis was to get acquainted with legislation that sets rules and demands for the use of pesticides and their analysis. The target was also to get acquainted with challenges in polar pesticides analysis and the methods that have been used in their analysis. In the experimental part the aim was to develop a new method for analysing mepiquat, chlormequat and ethephon in vegetables and fruits. The reason for developing a new method was a growing demand for a quick, simple, resource saving and selective method. The method was based on the QuPPe-method (Quick Polar Pesticides Method). Four columns that were suitable for analysing polar pesticides and several eluents and gradients were tested. The sample matrices were tomato, grape and apple. UHPLC-MS/MS equipment, which had a liquid chromatograph (Agilent Technologies) combined with a triple quadrupole mass spectrometer, was used. After testing the method was validated. The final method included extraction with acidic methanol, separation of the compounds by hydrophilic interaction chromatography (HILIC) and analysis by a triple quadrupole mass spectrometer. The limit of quantification (LOQ) for ethephon, chlormequat and mepiquat was acquired from the legislation and was based on maximum residue levels of the compounds (MRL, ethephon 0.05 mg/kg, chlormequat 0.01 mg/kg and mepiquat 0.02 mg/kg). The limit of detection (LOD) was for ethephon and chlormequat 0.001 mg/kg and for mepiquat 0.002 mg/kg. The recovery levels for these compounds varied between 92% and 131% depending on the matrix. The relative standard deviation varied between 3% and 63%. Because of the ion suppression, caused by sample matrices, the quantification was done by a standard addition method. The developed method was suitable for analysing ethephon, chlormequat and mepiquat in tomato, grape and apple samples repeatably. The sample preparation was simple and fast, which supports the idea of using this new method for routine analysis. The biggest problems were encountered when analysing ethephon because of its weak signals. The sample matrices tested caused different amounts of signal loss and the biggest loss was found in tomato samples in small concentrations.