ABSTRACT
Apple peel is frequently exposed to pesticides, especially in the last stages of the pesticide treatment practice. For a certain period, peel retains most of the applied pesticides, which precisely indicates the presence of pesticide residues. This study was conducted to establish and evaluate the method for the residue analysis of pyrimethanil, cyprodinil, trifloxystrobin, bifenthrin and boscalid by GC-MS in peel of Granny Smith, Golden Delicious and Idared varieties. The method consisted of few steps, without the routine usage of sorbents, and resulted in efficient removal of waxes, targeted as main interferences in GC-MS analysis. The matrix effect, boscalid selectivity issue, trend of lower trueness for bifenthrin in all matrices and for all analytes in Granny Smith matrix were in some way associated with the waxes. Finally, the method was applied to the analysis of three varieties of apple orchard samples, after 9 and 5 months of treatment with commercial formulations that contain pyrimethanil, cyprodinil and boscalid as active ingredients. Since the developed method consisted of few steps and used nontoxic and economic reagents, it could be implemented as a fast, economic and reliable screening method.
Subject(s)
Fruit/chemistry , Gas Chromatography-Mass Spectrometry/methods , Malus/chemistry , Pesticide Residues/analysis , Biphenyl Compounds/analysis , Biphenyl Compounds/chemistry , Limit of Detection , Linear Models , Niacinamide/analogs & derivatives , Niacinamide/analysis , Niacinamide/chemistry , Pesticide Residues/chemistry , Pyrimidines/analysis , Pyrimidines/chemistry , Reproducibility of Results , Waxes/chemistry , Waxes/isolation & purificationABSTRACT
Complexes of Co(II) ion with reduced low-molar pullulan (RLMP) (Mw 6000â¯g/mol) were synthesized in aqueous solutions at boiling temperature in the pH range from 7.5 to 13.5. Obtained Co(II)-RLMP complexes, with cobalt content â¼2-8% (AAS), were characterized by UV-Vis spectrophotometry, FTIR spectroscopy (ATR-FTIR, FT-IRIS), MALDI-TOF/TOF MS, and XRD. Tetragonally distorted Oh coordination of Co(II) ions with O ligand atoms in synthesized complexes is suggested based on the spectrophotometric data. No influence of complexation process on the 4C1 chair conformation of the d-glucopyranose units of pullulan was detected by ATR-FTIR measurements and FT-IRIS showed high homogeneity of synthesized complexes. Some additional depolymerization of pullulan during complex synthesis was indicated by MALDI-TOF/TOF MS but it also revealed good stability of complexes with much weaker binding of Co(II) ion in low molar mass fragments. Even in complexes with highest Co(II) ion content a low degree of crystallinity was detected by XRD analysis.
