毛细管气相色谱法测定水产品中多种有机磷农药残留的研究

建立了固相萃取-气相色谱法同时测定水产品中16种有机磷农药的多残留检测分析方法。样品经乙腈水溶液均质提取,利用盐析作用分离出乙腈层,应用C18和PSA串联柱净化后用GC-FPD检测分析,采用外标法定量。方法的检出限(S/N=3)为(0.003～0.006)mg/kg,加标水平为0.01 mg/kg时,方法回收率为(52.8～117)%,相对标准偏差为(4.0～11.5)%;加标水平为0.02 mg/kg时,方法回收率为(54.1～112)%,相对标准偏差为(3.1～10.4)%。     

Degradation Of Selected Herbicides In A Lowland Surface Water By Ozone And Ozone-Hydrogen Peroxide

The efficiency of ozone, and ozone in combination with hydrogen peroxide, for the degradation of five herbicides: Atrazine, Benazolin, Bentazone, Imazapyr and Triclopyr, under controlled laboratory conditions was investigated. Experiments were conducted at pH 7.5 in a bubble contactor column with a raw lowland surface water spiked with initial active ingredient concentrations of 2 μg/L. Mean consumed ozone doses were approximately 1, 2 and 3 mg O₃/L. Hydrogen peroxide was added simultaneously to the application of ozone in a series of six mass ratios, between 0.0 and 1.0, with each of the consumed ozone doses. The results demonstrated a greater but varying removal of all herbicides achieved with increasing consumed ozone and applied hydrogen peroxide doses.     

Method validation for 243 pesticides and environmental contaminants in meats and poultry by tandem mass spectrometry coupled to low-pressure gas chromatography and ultrahigh-performance liquid chromatography

An easy and reliable high-throughput analysis method was developed and validated for 192 diverse pesticides and 51 environmental contaminants (13 PCB congeners, 14 PAHs, 7 PBDE congeners, and 17 novel flame retardants) in cattle, swine, and poultry muscle. Sample preparation was based on the “quick, easy, cheap, effective, rugged and safe” (QuEChERS) approach using filter-vial dispersive solid-phase extraction (d-SPE) cleanup. Split final extracts were analyzed in parallel by low-pressure (vacuum outlet) GC-MS/MS and UHPLC-MS/MS (10 min each), providing an additional degree of confirmation for 55 overlapping LC- and GC-amenable pesticides. Analyte protectants were utilized to improve sensitivity and decrease matrix effects in GC analysis, and only filtration of initial extracts was enough to avoid ion suppression in UHPLC-MS/MS. The method was validated at three spiking levels (10, 25, and 100 ng/g) at or below established tolerance levels in the sample types. Satisfactory recoveries (70–120%) and RSDs ≤ 20% were achieved for 200 analytes. The validated method was successfully applied to the analysis of real-world incurred meat samples, further demonstrating the utility of the method for implementation in regulatory and commercial laboratories.     

Removal of Atrazine Through Ozonation in the Presence of Humic Substances

The presence of pesticides in water sources and their removal by treatment processes is of particular interest currently to water companies and research scientists. Although operators and scientists are debating whether the related standards and legislation are too stringent, the current European Drinking Water Directive stipulates a maximum contaminant level (MCL) of 0.1 μg/L for an individual pesticide. Atrazine is amongst the most frequently identified pesticides in water supply sources. Since conventional treatment processes (chlorination, coagulation and filtration) are unable to reduce this micropollutant to an acceptable concentration, two advanced technologies are being investigated extensively; namely, adsorption onto activated carbon, and ozonation, particularly ozone combined with hydrogen peroxide. As for ozonation, several authors (Glaze et al., 1987; McGuire and Gaston, 1988; Terashima, 1988; Ferguson et al., 1991) have reported that the removal of refractory organics (e.g., 2-methyl isoborneol – MIB and geosmin) by ozone appears to be more effective in natural waters than in pure water solution; this was attributed to the action of natural organic material in water (such as humic substances) which promotes the radical reactions of ozone. In other more fundamental studies (Staehelin and Hoigné, 1985; Xiong and Legube, 1991), humic substances were speculated to be involved in radical decomposition of ozone in solution.     

甲胺磷农药废水絮凝处理的生物可降解性

甲胺磷生产排放废水COD在1－1．5万mg／L左右，经用聚合硫酸铁絮凝处理后废水COD下降12％，经紫外分光扫描，絮凝后废水与原废水相比有机物呈均匀下降趋势。在活性污泥法的生化条件下的对比试验表明，在絮凝后甲胺磷废水COD高达4000mg/L以上，仍可进生化池处理，生化过程甲胺磷降解速度快，生化周期缩短一半。     

Photocatalytic oxidation of multicomponent systems of herbicides: Scale-up of laboratory kinetics rate data to plant scale

The reaction kinetics of the photocatalytic oxidation (PCO) of the herbicides isoproturon, simazine and propazine over irradiated TiO₂ (Degussa P25) suspensions were studied in multicomponent systems in a laboratory-scale annular photoreactor operated in recirculation batch mode. The multicomponent kinetic model established was then extended to take into account the direct effect of radiation absorbed by the TiO₂ photocatalyst in order to obtain intrinsic kinetic parameters independent of the radiation field in the photoreactor. An analysis of the radiation field in the photoreaction space was accomplished using a recently published Six-Flux Radiation Absorption-Scattering model (SFM) to decouple the values of the apparent reaction kinetic constants from the local volumetric rate of photon absorption (LVRPA) in the rate law of PCO of herbicide. The resulting rate laws with explicit dependence on the LVRPA were then used to predict, through accurate reactor modeling, the degradation of the herbicides in an optimal configuration of a flow-through, pilot-scale, falling film photoreactor. In a plant treatment scenario the total operating costs of the PCO of herbicides were calculated to be 3.75 Euro m⁻³.     

Application of Ultrasound‐Assisted Supercritical Extraction to Soil Remediation

The coupling of ultrasound to supercritical extraction with carbon dioxide has been evaluated as a green remediation technique for soils contaminated with pesticides. The study used samples of soil spiked with atrazine, an organophosphate and contaminant of widespread use. The influence of the operating temperature and pressure on the extraction of atrazine was studied. The extraction of atrazine was enhanced with the use of ultrasound relative to the results obtained from conventional supercritical extraction. This study, operated in semi‐continuous mode, demonstrates the possibility of increasing the yield of supercritical extraction by coupling with ultrasound instead of adding co‐solvents, which is a greener alternative for removing contaminants such as pesticides from soil matrices.     

Ethephon and fosetyl residues in fruits from São Francisco Valley,Brazil

ABSTRACT

This survey describes the occurrence of Ethephon (ETH) and Fosetyl in fruits intended for export produced in the São Francisco Valley, Brazil. The determination of these compounds was carried out by the QuPPe-method (Quick Polar Pesticides Method), which was optimised and successfully validated according to the SANTE/11813/2017. From January 2016 to December 2018 a total of 1048 samples were analysed for ETH residues. In 547 (53%) of the samples, residues below the EU MRL of 1 mg kg^?1 were present. In 17 samples (2%) ETH residues were above 1 mg kg^?1. Overall, the mean ETH level decreased after 2016. Analyses of fosetyl showed that (18%) of 109 mango samples were positive for this compound. Phosphonic acid was found in concentrations ranging from 0.12 to 3.2 mg kg^?1 and 5% of the measurements were above the EU MRL of 2 mg kg^?1. The results emphasise the quality control of fruits produced in this region.     

Optimisation of a solid-phase microextraction/HPLC/Diode Array method for multiple pesticide screening in lettuce

A new method was developed for the determination of 10 pesticides widely used in lettuce production (acetamiprid, azoxystrobin, cyprodinil, fenhexamid, fludioxonil, folpet, iprodione, metalaxyl, pirimicarb, and tolyfluanid) using solid-phase microextraction (SPME) and liquid chromatography (HPLC) with diode-array detection (DAD). The extraction performance of four different SPME coatings, polydimethylsiloxane (PDMS), PDMS/divinylbenzene (PDMS/DVB), carbowax/templated resin (CW/TPR), and polyacrylate (PA) was evaluated using an interface SPME–HPLC. CW/TPR fibre was selected as the most appropriate for the extraction of majority of these pesticides. Three variables (pH, NaCl% and extraction time) were considered key factors in the optimisation process. Interactions between these analytical factors and their optimal levels were investigated by response surface methodology based on central composite design. The method allowed the determination of azoxystrobin, cyprodinil, fenehexamid, fludioxonil, folpet, iprodione, and tolyfluanid in lettuce at concentrations between 0.8 and 25.6 mg/kg, i.e., bellow the maximum residues levels allowed for those compounds in lettuce. Lettuce samples that suffered pesticide treatments with folpet and fenehexamid were analysed during days to harvest to study the dissipation behaviour of the pesticides used. Concentration of folpet was 92.8; 53.4; 22.9; 17.9; 7.45; 1.85 mg/kg and concentration of fenhexamid was 158.1; 76.2; 31.0; 27.3; 7.24; 0.87 mg/kg, respectively for t₀, t₁, t₃, t₆, t₇, t₉ days, and not detected at t₁₄ days for the two pesticides.