Lorenzo Spanedda

Solid-phase extraction and high-performance liquid chromatographic determination of organic acids in honey

Abstract A high-performance liquid chromatographic method is reported that allows the determination of organic acids in honey after sample purification by solid-phase extraction. The chromatographic separation was achieved with two Spherisorb ODS-1 S5 columns connected in series and sulphuric acid (pH 2.45) as the mobile phase. The average recoveries of the acids ranged from 89% to 104% and the detection limits from 0.002 to 3 ppm (w/w).

High-performance liquid chromatographic separation of cyromazine and its metabolite melamine

(...) In this paper, the HPLC separation of cyromazine from melamine by means of columns with different mechanisms is reported

High-performance liquid chromatographic determination of dinitroaniline herbicides in soil and water

A high-performance liquid chromatographic method for the simultaneous determination of the dinitroaniline herbicides dinitramine, ethalfluralin, trifluralin, pendimethalin and isopropalin in soil and surface water is reported. The soil was extracted with diethyl ether and analysed without any clean-up. The water was analysed after purification and concentration on a C18 cartridge. The average recoveries were in the range 89-104%. The detection limits for the five herbicides were 0.02 mg/kg in dry soil and 0.5 micrograms/l in surface water.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF FENTHION AND ITS METABOLITES

Abstract The biotransformation of fenthion in animals and plants leads to five major metabolites: fenthion sulphoxide, fenthion sulphone, fenthion oxygen analogue (fenoxon), fenoxon sulphoxide and fenoxon sulphone. According to the FAO, the maximum residue limit for fenthion in different commodities includes the sum of the active ingredient and the above metabolites, expressed as fenthion. In this paper, a reversed- phase high-performance liquid chromatographic method is described which allows a rapid determination of fenthion and its major metabolites. A satisfactory separation was achieved with an RP-18 column and water—acetonitrile (50:50, v/v) as the mobile phase. Under these conditions the detection limits for fenthion and its major metabolites ranged from 0.005 to 0.02 ppm.

Interactions during fermentation between pesticides and oenological yeasts producing H2S and SO2

The degradative action of two strains of Saccharomyces cerevisiae, producers of large quantities of H2S and SO2, on eight sulphur-containing insecticides (chlorpyrifos-methyl, dimethoate, fenitrothion, fenthion, malation, methidation, parathion, and quinalphos) was studied. Moreover, the influence of these compounds on the fermentative activity of the yeasts was investigated. The yeasts adsorbed and degraded the studied insecticides to various extents, but their fermentative activity was not affected. A moderate adsorbtion (approximately 10% of the residue) was observed for chlorpyrifos-methyl, fenitrothion, parathion, and quinalphos. When absorbed, the insecticides were also degraded by about 50%. The degraded pesticides belong to the thiophosphates, while the dithiophosphates showed higher stability. The two yeast strains showed analogous degradative actions.

Residues of cymiazole in honey and honey bees

SUMMARYTen honey bee (Apis mellifera ligustica) colonies were treated with the acaricide cymiazole hydrochloride (Apitol) at the dose recommended for controlling Varroa jacobsoni: 2 g Apitol (17.5% a.i.) in 100 ml of 20% sugar syrup sprinkled on to the combs of each colony. Samples of honey and dead honey bees were collected for up to 112 and 15 days respectively after treatment and analysed using a liquid Chromatograph. Cymiazole residues in unsealed honey decreased from an average of 2.45 ppm 1 day after treatment to 0.14 ppm 112 days after treatment: in bees residues were 84.12 ppm after 1 day but decreased quickly and were 0.07 ppm after 15 days. The results suggest that honey bees can rapidly degrade this compound, but that levels higher than the permitted 0.01 ppm (in Italy) can easily occur in honey from treated colonies.

The transformation of organic acids in Vernaccia wine during flor formation

Abstract Three strains of Saccharomyces cerevisiae were used to study the transformations of organic acids in the Vernaccia wine during flor formation. All strains exhibited similar behaviour, differing only in the activity rate. Lactic acid was completely degraded, while malic, α-ketoglutaric and fumaric acids were formed. An analysis of the chromatograms showed the presence of some quantitatively significant unidentified acids.