Solid-phase microextraction-liquid chromatography-mass spectrometry applied to the analysis of insecticides in honey

Carbon aerogel-based solid-phase microextraction coating for the analysis of organophosphorus pesticides

The current study is focused on the in situ synthesis of a carbon aerogel (CA)-based solid-phase microextraction (SPME) fiber coating on stainless steel wire and evaluation of the suitability of CAs as SPME coating materials for the analysis of selected organophosphorus pesticides (OPPs) contained in environmental samples. A CA-based coating was obtained by pyrolyzing organic aerogels, which were prepared by the sol-gel polymerization of formaldehyde and 5-methylresorcinol, an oil shale processing by-product. The results demonstrated, for the first time, the in situ synthesis of a CA-based SPME fiber coating on stainless steel wire and its suitability for the extraction and preconcentration of six OPPs. Main parameters affecting the extraction efficiency were investigated and optimized. The direct immersion (DI)-SPME procedure combined with gas chromatography-mass spectrometry (GC-MS) for the simultaneous analysis of selected OPPs was successfully applied to the efficient and sensitive determination of analytes of interest in environmental matrices of honey and natural water samples. The developed CA-coated SPME fiber showed good linearity (R² = 0.981-0.994), low detection limits (0.11-0.83 μg L^-1) and satisfactory single fiber and fiber-to-fiber reproducibilities (8.8-12.3%, n = 5 and 11.4-17.2%, n = 3). The performance of the CA-coating was compared with that of commercially available SPME fiber coatings.

Spectrophotometric detection of fenthion in foods after extraction by magnetic zirconia

A magnetic material, Fe₃O₄@ZrO₂, was used to enrich an organophosphorus pesticide, fenthion. After enrichment the Fe₃O₄@ZrO₂ was treated with NaOH to elute and hydrolyze fenthion. The hydrolysis products, orthophosphate ions, combine to molybdate ions to yield molybdophosphoric acid, which was further reduced with SnCl₂ to obtain a blue phosphatemolybdate. The content of orthophosphate ions as well as fenthion can be determined through the spectrophotometric method. Adsorption and elution conditions were optimized to obtain an enrichment factor of 12.5. The proposed composite method was successfully used to analyze the fenthion residues on the skin of cucumber and apple samples. The limit of detection was as low as 0.037 mg/Kg, which was close to that of the gas chromatography-mass spectrometer method. The method was simple, rapid, and economic, suitable for the rapid screen of fenthion and the other organophosphorus pesticide in mass samples.

The occurrence of pesticides and persistent organic pollutants in Italian organic honeys from different productive areas in relation to potential environmental pollution

Bee products, such as honey, are widely consumed as food and consumer interest is currently oriented towards organic foods. Regarding this, the European Commission establishes that the qualification of organic honey and other beekeeping products as being from organic production is closely bound with the characteristics of hive treatments as well as the quality of the environment. Agricultural contamination with pesticides is a challenging problem that needs to be fully addressed, in particular in the field of organic production systems. In this study, the occurrence of different classes of contaminants selected as representative of potential contamination sources were investigated in 59 organic honeys: organochlorines, OCs; organophosphates, OPs; polychlorobiphenyls, PCBs and polybromodiphenylethers, PBDEs. A method based on Accelerated Solvent Extraction with "in line" clean-up and GC-MS/MS detection was developed to detect contaminants. Residues of many pesticides were found in most of the samples investigated. The majority of honey samples contained at least one of the pesticides, even if their concentrations were found to be lower than its MRL. Diazinon, Mevinphos, Coumaphos, Chlorpyrifos and Quinoxyfen were the residues frequently detected in samples coming from the apple and citrus orchard areas. Furthermore, the results of the present study show that the presence of the residue in organic honey may also be affected by the geographical area (e.g. the presence of an agricultural system) confirming honey bee and beehive matrices as appropriate sentinels for monitoring contamination in the environment. The optimised method proved to be simple and rapid, requiring small sample sizes and minimising solvent consumption, due to the ASE having an "in line" clean-up step.

Residues of organochlorine and synthetic pyrethroid pesticides in honey, an indicator of ambient environment, a pilot study

Samples of honey were screened to monitor residues of organochlorine and pyrethroid pesticides. The study meant to examine the quality of honey, and to use honey as a bioindicator of environmental contamination. Residue levels were determined by gas chromatography (GC-μECD). Samples had a wide spectrum of organochlorine and synthetic pyrethroids pesticides, with hexachlorobenzene (HCB) as the most frequently detected organochlorine, followed by permethrin, heptachlor epoxide. Only one sample had a concentration of γ-HCH higher than maximum residue limit of honey (0.01 mg kg(-1)). Residues of organochlorines detected, indicate the presence of some fresh supplies, despite the ban imposed on their use. The study confirmed that honey bee and beehive matrices could be used as gauge for monitoring environment contamination. From public health point of view, the observed levels of pesticide residues in honey do not pose a serious health risk to the consumers, but raises questions of the source of organochlorines.

Solid-phase extraction for multi-residue analysis of pesticides in honey

A fast and simple multi-residue method for the analysis of 15 organophosphorus (OP), 17 organochlorine (OC), 8 pyrethroids (PYR), 12 N-methyl-carbamate (NMC) pesticide residues and bromopropylate in honey is presented. Ready-to-use EXtrelutNT 20 column, eluted with dichloromethane, was used to extract the pesticide residues from the aqueous-acetone honey sample, obtaining a clean extract directly analyzable. Determination was carried out by gas chromatography (GC) coupled with flame photometric detector (FPD) for OP compounds and by GC coupled with mass spectrometry detector (MSD) for OC and PYR pesticides and bromopropylate. The NMC pesticides were analysed by liquid chromatography-double derivatization coupled with spectrofluorimetric detector (LC/DD/Fl). This method allows the determination of the 53 pesticide residues at low concentrations (0.0005-0.074 mg/kg) and can be used to assess the compliance with the Maximum Residues Levels (MRLs) set by the European Union. The performance of the method was evaluated and specificity, linearity, recovery, repeatability, reproducibility, limit of quantification (LOQ) and limit of detection (LOD) were determined. A good linearity (r(2)≥ 0.99) was found in the range 0.0005-0.074 mg/kg for the majority of the compounds studied. Most of the pesticides had recoveries in the range 70-103 % and values of relative standard deviation (RSD) < 20 for repeatability and reproducibility, showing good accuracy and precision of the method. Aldicarb partially degraded in aldicarb sulphoxide during the analytical procedure, giving anomalous values. The LOQ for all pesticides investigated was from 0.0005 to 0.025 mg/kg while the LOD ranged from 0.0002 to 0.008 mg/kg.