Danyu Shen

Residue levels and risk assessment of pesticides in nuts of China

The pesticide residue levels of three nuts (chestnut, walnut, pinenut) collected from seven main producing areas of China were investigated. Twenty-nine pesticides, including organophosphates (OPs), organochlorines (OCs), pyrethroids (PYs) and two fungicides (triadimefon and buprofezin) were analyzed by gas chromatography (GC). Four OPs (acephate, dimethoate, chlorpyrifos and parathion-methyl) were found in 11.4% samples, with the concentrations of 19.0 µg kg(-1) to 74.0 µg kg(-1). Six OCs (DDT, HCH, endosulfan, quintozene, aldrin and dieldrin) were found in 18.2% samples, with the concentrations of 2.0 µg kg(-1) to 65.7 µg kg(-1). Among OCs, p,p-DDE and α-HCH were the dominant isomer for DDT and HCH. Five PYs (fenpropathrin, fenvalerate, cypermethrin, bifenthrin and cyhalothrin) were found in 15.9% samples, with the concentrations of 2.5 µg kg(-1) to 433.0 µg kg(-1). Fenpropathrin was the most frequently detected pesticide. In addition, triadimefon and buprofezin were detected only in two samples. For the tested nuts, 25.0% samples with multiple residues (containing more than two pesticides) were noted, even up to 9.1% samples with five pesticide residues. The residue of 15.9% samples was higher than the maximum residue limits (MRLs) of China. The short-term risks for the tested nuts were below 1.2%, and the highest long-term risk was 12.58%. The cumulative risk (cHI) for the tested pesticides were 8.43% (OPs), 0.42% (OCs), 12.82% (PYs) and 0.15% (fungicides), respectively. The total cHI was 21.82%. There was no significant health risk for consumers via nuts consumption.

Time-dependent movement and distribution of chlorpyrifos and its metabolism in bamboo forest under soil surface mulching.

The dissipation and distribution of chlorpyrifos (CHP) granule formulation in bamboo forest under soil surface mulching conditions (CP) and noncovered cultivation conditions (NCP) from soil to product were investigated. In the CP treatment, the CHP granule with slow-release effect leached from the topsoil to the subsoil. Conversely, the CHP was fixed in the topsoil (0-5 cm layer) in the NCP treatment, and no obvious leaching effect could be observed. The residue of CHP could be found in bamboo shoots from CP treatment, mainly at the bottom part (5 cm length). CHP could be degraded into 3,5,6-trichloro-2-pyridinol (TCP) in the soil and bamboo shoots. In addition, the straw used as the mulching material with higher OM and pH had some regulatory role in changing the pH and OM characteristics of the soil. Thus the straw could indirectly affect the adsorption and degradation behavior of CHP and TCP in the soil.

Optimization of a One‐Step Method for the Multiresidue Determination of Organophosphorous Pesticides in Camellia Oil

UNLABELLED Due to the widespread use and potential toxicity of organophosphorous pesticides (OPs), multiresidue monitoring of OPs in camellia oil has become increasingly important. A simple, rapid, and effective matrix solid-phase dispersion extraction for the determination of 15 organophosphorous pesticides in camellia oil is described. Related important factors influencing the extraction efficiency, such as type of sorbent material, eluting solvent, and ratio of sample/sorbent were studied and optimized. The best results were obtained using 0.5 g of camellia oil, 1.5 g of white carbon black as dispersant sorbent, and 5 mL of acetonitrile: ethyl acetate (2:1, V/V) as eluting solvent. Method validation was performed in order to study sensitivity, linearity, precision, and accuracy. Average recoveries ranged between 76.7% and 102.9% with relative standard deviation values from 2.9% to 13.7% at 2 concentration levels (10 and 100 μg/kg). The method limit of detection at or below the regulatory maximum residue limits for the pesticides was achieved. PRACTICAL APPLICATION A simple, rapid, and effective method for multiresidue determination of organophosphorous pesticides in camellia oil was developed. The sample preparation could finish in 5 min.

Environmental behaviors of phoxim with two formulations in bamboo forest under soil surface mulching.

Phoxim (emulsifiable concentrate (EC) and granules (G)) has been widely used in bamboo forests. The persistence and magnitude of phoxim residues in the crop and soil must be investigated to ensure human and environmental safety. The environmental behaviors of the two formulations were investigated in a bamboo forest under soil surface mulching conditions (CP) and non-covered cultivation conditions (NCP). The half-lives of phoxim in soil under the two conditions in soil were 4.1-6.2days (EC) and 31.5-49.5days (G), respectively. Phoxim in EC could be leached from the topsoil into the subsoil. A minimized leaching effect was observed for G under NCP. Inversely, an enhanced leaching effect was observed for G under CP. The G formulation resulted in more parent compound (in bamboo shoots) and metabolite (in soil) residues of phoxim than in the case of EC, especially under CP conditions. In addition, the intensity and duration of the formulation effect on soil pH adjustment from G were more obvious than that from EC. Results showed that the environmental behaviors (distribution, degradation, residue) of phoxim in the bamboo forest were significantly influenced by the type of formulation. The prolongation effect from phoxim G might cause persistence and long-term environmental risk. However, bamboo shoot consumption could be considered relatively safe after applying the recommended dose of the two phoxim formulations.

Multielemental Analysis of Camellia Oil by Microwave Dry Ashing and Inductively Coupled Plasma Mass Spectrometry

A simple and practical method is reported for the determination of Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb in camellia oil by inductively coupled plasma-mass spectrometry (ICP-MS). Camellia oil was treated using microwave dry ashing at 380 degree Celsius for carbonization and 550 degree Celsius for ashing in a 110 minute procedure. The operational conditions of the dynamic reaction cell with ammonia as the reaction gas were optimized to minimize interferences. The recoveries and the relative standard deviations of optimized method were between 85.6 and 98.4 percent and 1.1 and 5.5 percent, respectively. The detection limits for Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb were 31, 48, 0.6, 4, 22, 0.4, 0.6, 0.9, 3, and 1 micrograms per kilogram, respectively. The developed method has significant potential for the determination of metals in edible oils.

Simplified Determination of Organophosphorus Pesticides in Camellia Oil

ABSTRACT A rapid, simple, and economical analytical approach has been developed and evaluated for the determination of six organophosphorus pesticides in camellia oil. This method is based on dispersive liquid−liquid microextraction (DLLME) following simple extraction. Oil was extracted with methanol by a high-speed blender and filtered with glass paper to remove fat. The filtrate was incorporated in the DLLME procedure. Acetonitrile was used as the dispersive solvent and chloroform as the extraction solvent. The residues were analyzed by gas chromatography–mass spectrometry. Under the optimized conditions, the recoveries were between 78.4 and 112.8% with relative standard deviations less than 12.3%. The limits of detection for the analytes were from 0.0003 to 0.0056 mg · kg−1. The optimized method was used for the determination of organophosphorus pesticides in camellia oil.

The Fate of Organophosphorus Pesticides during Camellia Oil Production

The purpose of this study was to investigate the fate of organophosphorus pesticides (OPs) during camellia oil production process, from camellia fruit to the final oil product. The results showed that the OPs were mainly distributed in the peel of camellia fruit, basically above 40% after the pesticide application of 7 d (P < 0.05). A small amount of OPs could enter into the seed and convert to crude camellia oil, with the concentration of 19.5 to 548.2 mg/L. In addition, metabolites of OPs (25.7 to 768.9 mg/L) could be detected in the crude camellia oil. Moreover, the refining process (degumming, deacidfying, bleaching) had a significant effect on the removal of OPs from the crude camellia oil (P < 0.05), and the effect was related to the octanol-water partition constant (LogP) of pesticide. The larger the LogP, the more stable the OPs were during refining process. The final refined camellia oil was found to have no detectable levels of OPs metabolite.

Uptake effects of toxic heavy metals from growth soils into jujube and persimmon of China

Compared with other agricultural plants, information about uptake effects of toxic heavy metals from growth soils into persimmon and jujube are scarce. In this study, the single and comprehensive uptake effects of five toxic heavy metals (Pb, As, Cd, Cr, and Hg) between the two fruits and their growth soils were investigated. The results showed that the average concentrations of heavy metals in the two fruits were found to be 30 (Pb), 6.6 (As), 2.3 (Cd), 38 (Cr), and 0.33 (Hg) μg/kg, respectively. The average concentrations of heavy metals in their growth soils were 26.31 (Pb), 9.63 (As), 0.12 (Cd), 57.6 (Cr), and 0.049 (Hg) mg/kg, respectively. An uptake effect was observed for the two fruits. The values of Nemerow pollution index (NPI) in the two fruits and their growth soils were 0.10 and 0.55, respectively. The average bioconcentration factor (BCF) values of Pb, As, Cd, Cr, and Hg in the two fruits were 0.0012, 0.00075, 0.021, 0.00077, and 0.012, respectively. Based on the residue levels of toxic heavy metals in the growth soils and soil parameters, the prediction models for NPI and BCF were established, with the adjusted regression coefficients of 0.65 (NPI) and 0.81 (BCF). The contribution rates of different soil parameters to NPI were 21.7% (OC), 16.1% (Pb), 17.1% (Cr), 19.8% (Cd), and 25.4% (As), respectively. The contribution rates of different soil parameters to BCF were 10.2% (OC), 9.4% (Cr), and 80.4% (Cd), respectively.