A Photochemistry Technique Using Ultraviolet Irradiation Followed by Gas-Liquid Chromatography to Confirm the Identity of Some Organochlorine Pesticides

Abstract

A procedure involving ultraviolet (UV) irradiation followed by gas-liquid chromatographic (GLC) detection of photodecomposition products to confirm the identity of selected organochlorine pesticides is described. The Irradiation intensity was standardized by determining the position relative to the UV source which resulted in equal GLC peak heights for the parent compound and major photo-decomposition product after 8 minutes of exposure of a solution of heptachlor epoxide in isooctane. Chromatograms showing photo-decomposition patterns for 33 compounds are presented. Observations and comments on the applicability of this technique to organo-chlorine pesticide residue confirmation are reported.     

Multiresidue Method for the Determination of Organophosphorus Pesticides in Still Wine and Fortified Wine Using Solid-Phase Microextraction and Gas Chromatography – Tandem Mass Spectrometry

A SPME-GC-MS/MS method for the determination of eight organophosphorus pesticides (azinphos-methyl, chlorpyriphos, chlorpyriphos-methyl, diazinon, fenitrothion, fenthion, malathion, and methidathion) in still and fortified wine was developed. The extraction procedure is simple, solvent free, and without any sample pretreatment. Limits of detection (LOD) and quantitation (LOQ) values in the range 0.1–14.3 µg/L and 0.2–43.3 µg/L, respectively, were obtained. The LOQ values are below the maximum residue levels (MRLs) established by European Regulation for grapes, with the exception of methidathion. Coefficients of correlation (R²) higher than 0.99 were obtained for the majority of the pesticides, in all different wines analyzed.     

Trace Metal and Persistent Organochlorine Levels in Wood Bison (Bison bison athabascae) from the Mackenzie Bison Sanctuary

Abstract

Tissue samples were collected from ten healthy mature female wood bison (B. bison athabascae) for examination. Livers and kidneys were tested for toxic heavy metals and trace metals considered as essential nutrients for successful reproduction, while fat samples were analyzed for persistent chlorinated hydrocarbons. No elevated levels of toxic heavy metals (arsenic, cadmium, lead, mercury) were found and essential trace elements (copper, manganese, selenium, zinc) were within the acceptable ranges established for healthy cattle. All fat samples tested contained trace levels of α-BHC (mean value, 23 ppb) and lindane (mean value, 3 ppb).     

Electrochemical Determination of Fenitrothion Organophosphorus Pesticide Using Polyzincon Modified‐glassy Carbon Electrode

In this paper, a glassy carbon electrode (GCE) was modified with polyzincon. The modified electrode was used as a simple, inexpensive and highly sensitive electrochemical sensor for the determination of organophosphorus pesticide fenitrothion. To fabricate the electrochemical sensor, GCE was immersed in 0.10 mmol L⁻¹ zincon solutions at pH 7.0 and then successively scanned between −1.00 to 2.20 V (vs . Ag/AgCl) at a scan rate of 70 mV s⁻¹ for six cycles. The morphology and structure of the polyzincon were studied with atomic force microscopy and scanning electron microscopy. A comparison of the electrochemical behavior of fenitrothion on the unmodified and polyzincon modified‐GCE showed that in the modified electrode not only the oxidation peak current increased, but also the overpotential shifted to lower one. The experimental conditions such as sample solution pH, accumulation potential, and time were optimized. The differential pulse voltammetric responses of fenitrothion at potential about −0.60 V was used for the determination of fenitrothion. The peak current increased with increasing the concentration of fenitrothion in the range of 5 to 8600 nmol L⁻¹ with a detection limit of 1.5 nmol L⁻¹. Finally, the electrochemical sensor was used for the analysis of fenitrothion in water and fruit samples.     

Low‐density extraction solvent based solvent‐terminated dispersive liquid–liquid microextraction for quantitative determination of ionizable pesticides in environmental waters

A rapid, efficient, and new solvent terminated dispersive liquid–liquid microextraction technique coupled with HPLC was developed for selective extraction and analysis of s‐triazine herbicides from environmental water samples. Important parameters influencing the extraction process including type and volume of extraction and disperser solvent, extraction time, sample pH, ionic strength, and extraction temperature were successfully optimized. Under the optimal conditions, there are excellent linear relationships between the analytical results and concentration in the range of 10–400 mg/L for atrazine, propazine, prometryn, and terbutryn. LOD and LOQ ranged from 0.60 to 2.33 μg/L and 2.0 to 7.7 μg/L, respectively. Performance of the analytical technique was evaluated by carrying out the repeatability and reproducibility analyses that were ranged from 2.86 to 5.66% and 4.64 to 5.89% for 100 μg/L of each target analyte, respectively. The proposed method has been successfully applied to the analysis of real water samples and acceptable relative recoveries over the range of 65.93–101.46%, with RSDs ≤ 8.80%, were obtained. The overall results have been compared with the literature values. Thus, the method developed could efficiently be used for selective extraction of the target analytes from complex matrices, particularly environmental waters.     

Graphene grafted silica‐coated Fe3O4 nanocomposite as absorbent for enrichment of carbamates from cucumbers and pears prior to HPLC

In this paper, a novel graphene (G) grafted silica‐coated Fe₃O₄ nanocomposite was fabricated by the chemical bonding of G onto the surface of silica‐coated Fe₃O₄ nanoparticles. Some carbamates (metolcarb, carbaryl, pirimicarb, and diethofencarb) in cucumber and pear samples were enriched by this nanocomposite prior to their determination by HPLC with UV detection. Experimental parameters that may affect the extraction efficiency were investigated. Under the optimum conditions, a linear response was achieved in the concentration range of 0.5–100.0 ng/g for metolcarb, carbaryl, and diethofencarb, and 1.0–100 ng/g for pirimicarb with the correlation coefficients (r) ranging from 0.9956 to 0.9984. The LOD (S/N = 3) of the method were found to be in the range from 0.08 to 0.2 ng/g. The RSDs were in the range from 2.4 to 5.8%. The results indicated that the G grafted silica‐coated Fe₃O₄ nanocomposite was stable and efficient for magnetic SPE and has a great application potential for the preconcentration of other organic pollutants from real samples.     

Determination of Anionic Surfactants in Water

The use of ternary complexes in the determination of anionic surfactants has been investigated and an analytical method using linear alkyl sulfonates as a test substance has been developed. The method involves the formation of the chloroform-extractable bisphenanthroline Cu(II)-linear alkyl sulfonate (LAS) complex and the subsequent equilibration of the extract with erythrosine to form the extractable bisphenanthroline Cu(II)-erythrosine complex. In the equilibration step erythrosine displaces LAS quantitatively, allowing the determination of the LAS originally present by measuring the absorbance of the extracted bisphenanthroline-Cu(II)-erythrosine complex. Results are reported of studies made to determine the optimum analytical conditions, the sensitivity, and the precision for the method described.     

Dispersive liquid–liquid microextraction followed by high-performance liquid chromatography for the determination of three carbamate pesticides in water samples

A simple, rapid and efficient method, dispersive liquid–liquid microextraction (DLLME) in conjunction with high-performance liquid chromatography (HPLC), has been developed for the determination of three carbamate pesticides (methomyl, carbofuran and carbaryl) in water samples. In this extraction process, a mixture of 35 µL chlorobenzene (extraction solvent) and 1.0 mL acetonitrile (disperser solvent) was rapidly injected into the 5.0 mL aqueous sample containing the analytes. After centrifuging (5 min at 4000 rpm), the fine droplets of chlorobenzene were sedimented in the bottom of the conical test tube. Sedimented phase (20 µL) was injected into the HPLC for analysis. Some important parameters, such as kind and volume of extraction and disperser solvent, extraction time and salt addition were investigated and optimised. Under the optimum extraction condition, the enrichment factors and extraction recoveries ranged from 148% to 189% and 74.2% to 94.4%, respectively. The methods yielded a linear range in the concentration from 1 to 1000 µg L^?1 for carbofuran and carbaryl, 5 to 1000 µg L^?1 for methomyl, and the limits of detection were 0.5, 0.9 and 0.1 µg L^?1, respectively. The relative standard deviations (RSD) for the extraction of 500 µg L^?1 carbamate pesticides were in the range of 1.8–4.6% (n = 6). This method could be successfully applied for the determination of carbamate pesticides in tap water, river water and rain water.     

A Chemical Test for Determining Biological Availability of Aged Chemicals in Soil

Abstract

Aging is one of several processes that are known to affect exposure of chemicals to organisms by decreasing the available fraction of chemical contaminants in soil. This phenomenon has important implications in the assessment of the hazards of chemicals and regulations for soil cleanup. Passive sampling devices (PSDs) are potentially direct chemical indicators for assessing bioavailability of pesticides (and other chemicals). PSDs consist of lipophilic material within a semi-permeable membrane, similar to biological systems. In this study, a pesticide mixture was aged in soil for up to eight months. Earthworms and PSDs were placed in soil and chemical uptake into both was determined over time. Uptake rates into PSDs and maximum concentrations were observed to positively correlate with uptake rates and maximum concentrations in earthworms for both of the soil types studied (sandy loam, silt loam). These results indicate that PSDs may be used as a surrogate for earthworms and provide a chemical technique for assessing the availability of aged chemical residues in soil.     

Organochlorine Pesticides in Water,Sediment and Fish from the Nile River and Manzala Lake in Egypt

Abstract

To assess the risks of organochlorine pesticides discharged into the hydrospheric environment of Egypt, river and lake water, drinking water, suspended solids, sediments and fish were collected during 1993—1994 from the Nile River and Manzala Lake in Egypt and were transported to Japan for chemical analysis. Among different organochlorine pesticides analyzed, p,p′-DDE was the most predominant in fish (7.6 to 67 ng/g wet wt.), sediments (3.2 to 432 ng/g dry wt.) and suspended solids (5.3 tc 138 pg/L). However, in the dissolved phase of water samples HCH compounds predominated (α-HCH, 71 to 2,815 pg/L). Concentrations of organochlorine pesticides, except chlordane, were higher in Manzala Lake than in the River Nile. Concentrations of organochlorine pesticides in fish corresponded with those in sediments from each location. Comparison of organochlorine concentrations in Nile River water with those reported in earlier studies suggested a decrease in concentrations during the last decade. However, concentrations of p,p′-DDE has increased in fish. It appears that the release of this metabolite from contaminated sediment is the major source of p,p′-DDE in fish during recent years.