Gian Pietro Molinari

Phytochemical constituents and in vitro radical scavenging activity of different Aloe species.

The phytochemical profile of Aloe barbadensis Mill. and Aloe arborescens Mill. was investigated using colorimetric assays, triple quadrupole and time-of-flight mass spectrometry, focusing on phenolic secondary metabolites in the different leaf portions. Hydroxycinnamic acids, several characteristic anthrones and chromones, the phenolic dimer feralolide and flavonoids such as flavones and isoflavones were identified. The stable radical DPPH test and the ORAC assay were then used to determine the in vitro radical scavenging. The outer green rind was the most active, while the inner parenchyma was much less effective. The 5-methylchromones aloesin, aloeresin A and aloesone were the most active among the pure secondary metabolites tested. The results suggest that several compounds are likely to contribute to the overall radical scavenging activity, and indicate that leaf portion must be taken into account when the plant is used for its antioxidant properties.

Residues of the herbicide fenoxaprop-P-ethyl, its agronomic safener isoxadifen-ethyl and their metabolites in rice after field application.

BACKGROUND Fenoxaprop-P-ethyl is a herbicide used on cereals and in particular on rice, the degradation of which leads to several relevant metabolites. The herbicide is used together with an agronomic safener such as isoxadifen-ethyl, which also generates some metabolites. The present work was aimed at developing and validating an analytical method for the determination of the above parent compounds and their main metabolites in the edible fractions of rice. Parent compounds were extracted in acetonitrile and determined by gas chromatography with a mass spectrometer detector, while metabolites were extracted in acetonitrile and analysed by liquid chromatography tandem mass spectrometry. RESULTS The method was validated through recovery tests in rice straw, grain and plant: accuracy was in the range 76-86% and 90-103% for parent compounds and metabolites respectively. Precision, as relative standard deviation, was in the range 3-11% and 6-17% for parent compounds and metabolites respectively. The limit of detection was 0.01 mg kg(-1) for each analyte, while the limit of quantification was set at 0.05 mg kg(-1). CONCLUSION The analytical method is suitable for quantitative determination of each analyte considered in rice commodities.

Rapid determination of lycopene and β-carotene in tomato by liquid chromatography electrospray tandem mass spectrometry

BACKGROUND The tomato fruit is a dietary source of carotenoids, bioactive antioxidant compounds that play an important role in the prevention of degenerative diseases. Several extraction and detection techniques regarding carotenoids in tomatoes can be found in the literature, mainly based on high-performance liquid chromatography separation and ultraviolet-visible detection. RESULTS The best extraction conditions and tandem mass spectrometry (MS) analysis were evaluated: lycopene and β-carotene were extracted in a cyclohexane/ethyl acetate mixture without the addition of antioxidants, next separated by liquid chromatography on a C(18) column and then determined through electrospray tandem MS. Ionic suppression by the matrix in negative ionisation mode did not allow the analysis of extracts, hence the positive ionisation mode was chosen. Validation parameters demonstrated the suitability for purpose of the analytical method: accuracy, precision, linearity and detection limits were adequate. The method was finally applied to different tomato samples, and differences could be easily highlighted. CONCLUSION The method was simple, fast and appropriate for the purpose of analysing lycopene and β-carotene in tomatoes.

Performance and Matrix Effect Observed in QuEChERS Extraction and Tandem Mass Spectrometry Analyses of Pesticide Residues in Different Target Crops

The method performance and matrix effect related to quantitative determination of pesticide residues was assessed after QuEChERS extraction and LC-MS-MS analysis. Dicloran, phosmet and phosmet-oxon, pirimiphos-methyl, and BNOA were analyzed in peach, apple, melon, cereals, tomato, and strawberry. The matrix effects, as well as recovery and process efficiencies, were determined for a fungicide, two insecticides, and a plant growth regulator. Crop samples were spiked either pre- or post-extraction, then the peak area was compared with the peak area in neat solvent. The mean recovery ranged from 73% to 98%, and repeatability (as RSD) was between 3% and 16%, depending on the compound and spiking level. The matrix effect occurred as ionic suppression and was found in the range of 5% to 22% depending on the compound. Recovery efficiencies were good and substantially comparable, being in the range of 93-96%. Although the suppression observed still appears to be acceptable considering the overall process efficiency, it seems evident that the matrix effect is important when a reliable quantitative method must be applied.

Focus on toxicological aspects of pesticide chemical interaction in drinking water contamination.

Toxicological aspects related to chemical and microbial degradation of pesticides in water and to products deriving from the interaction with xenobiotics found in water are reviewed. Other aspects considered are those related to compounds formed in potabilization processes and to water contamination by pesticide synthesis by-products or intermediates. These problems refer to scarcely investigated issues which are nevertheless very interesting because of their impact on human health.

Effect of different formulations on tebuconazole residues in stone fruits.

BACKGROUND The correlation between pesticide residue levels and formulation of an active substance is often not considered, even if it is reasonable to expect some differences arising from behaviour during dilution and spraying, from adhesion to plant and from degradation. An experimental study to investigate the magnitude of tebuconazole residues as a function of different tebuconazole formulated products was carried out in Italy. The fungicide was applied as wettable powder (WP) and water-dispersible granule (WG) formulations to peach, plum, apricot and nectarine orchards, on four different sites. The fruit samples gained from the field trials were quantitatively analysed by gas chromatography with a nitrogen phosphorus detector (GC/NPD) for tebuconazole residues. RESULTS Tebuconazole residues in the fruits gained from the plot treated with the WP formulation, 14 days after application, were in the range 0.01-0.07 mg kg(-1), while corresponding residues in the plot treated with the WG formulation were in the range 0.01-0.06 mg kg(-1). CONCLUSION No significant differences in the residue levels of tebuconazole could be observed between the trials conducted with the WP and the WG formulation.

Residues of pirimiphos-methyl in cereals and processed fractions following post harvest spray application.

The aim of this work was to comparatively assess the persistence of pirimiphos methyl residues in cereals and in their milling fractions after spray application in post harvest. An analytical method, based on a slightly modified QuEChERS extraction followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) determination was validated: mean recovery was in the range 73 % to 92 % depending on the spiking level, and precision as RSD ranged from 11 % to 16 %. The analysis of treated samples revealed that pirimiphos-methyl residues were highly persistent and that no differences could be observed between wheat, durum wheat and oat. As far as the impact of the milling process on residues is concerned, pirimiphos methyl contamination was significantly reduced during both cleaning and processing, and most of the contamination was related to outer kernel fractions.