Assessment of insecticide risk to human health in groundwater in Northern China by using the China-PEARL model.

BACKGROUND: Insecticides are extensively used in China and may leach to groundwater, which is used as a source of drinking water in Northern China. However, the risk of insecticide leaching to groundwater and the subsequent risk to human health caused by the consumption of insecticide-contaminated drinking water remain unclear. RESULTS: A total of 336 predicted environmental concentrations (PECs) were simulated for 32 commonly used insecticides, and 171 PECs were calculated for 20 metabolites in six agricultural dry-land scenario locations of Northern China with eight target crops. In 264 of the 336 cases, the PEC in groundwater is ≤0.1 µg L-1 . Carbofuran, imidacloprid, trichlorfon and oxidative metabolites of aldicarb are the most leached chemicals in groundwater. The most vulnerable crop is cotton, whereas soil treatment is the most vulnerable application type. Urumqi and Weifang are the most vulnerable among the six scenario locations. Less than 3% of 336 cases show unacceptable risk of insecticide-contaminated groundwater, thereby requiring higher risk assessment and risk mitigation. The unacceptable cases are the leaching of carbofuran for cotton growing in Urumqi and Weifang, and leaching of metabolites of aldicarb in cotton and tobacco scenarios. CONCLUSION: Popular insecticides used in Northern China are generally safe to groundwater. © 2017 Society of Chemical Industry.

Dissipation and residue determination of fluoroglycofen-ethyl in soybean and soil by UPLC-MS-MS.

A rapid, highly selective, and sensitive method was developed for detecting fluoroglycofen-ethyl in soybean seed, plant, and soil using UPLC-MS-MS. The detection limits of fluoroglycofen-ethyl in soybean seed, plant, and soil were 0.5, 1, and 1 µg kg(-1), respectively. Recoveries ranged from 83.4% to 99.2%, in which intra-day RSDs were from 1.3% to 6.7% and inter-day RSDs were from 1.9% to 7.0%. In the dissipation study, the half-lives of fluoroglycofen-ethyl were 34.8 (Shanxi) and 48.5 h (Heilongjiang) in soil and 43.3 h in soybean plant in both locations. The residues of fluoroglycofen-ethyl in all samples were below LODs 30 days before and during harvest.

Bioconcentration study of Xinjunan in zebrafish.

An experiment was carried out to determine the acute toxicity and bioconcentration factor of Xinjunan in zebrafish under semi-static test method. The result of the 96-h LC(50) values (0.31 mg/L), at 95% confidence limit, revealed that Xinjunan was highly toxic. Bioconcentration factor after 8 days exposure, 451.0 and 273.2, respectively, at two concentrations, were at medium bioconcentration range. To determine Xinjunan residues in water and fish, a method was developed by using a liquid-liquid distribution and a cationic exchange solid-phase extraction method to extract and clean up Xinjunan in fish, and then using a weak cationic exchange column with gradient elution and second-order mass spectrometry with selected reaction monitoring mode detection. This method found a good linear relationship (r > 0.99), the lowest limit of quantification with a signal-to-noise ratio of 10:1 was 0.02 [Formula: see text]g/L in water and 5 [Formula: see text]g/kg in fish, the recovery ranged from 97% to 109% for water and fish at different levels with a coefficient of variation less than 5%. The accuracy, precision, and lowest limit of detection of the method used for residue analysis of Xinjunan in water and fish can meet environmental exposure monitoring requirements. The results of the acute toxicity and bioconcentration provide a basis for environmental risk analysis of Xinjunan.

Stereoselective degradation of fungicide triadimenol in cucumber plants.

The stereoselective degradation of triadimenol in different cucumber plant tissues (root, stem, leaf, and fruit) has been investigated. Rac-triadimenol was applied to cucumber plants by root irrigation mode under field conditions. The degradation kinetics and the enantiomer fraction were determined by normal-phase high-performance liquid chromatography with diode array detector and on-line optical rotatory dispersion detector on Chiralpak AS-H column. It has been shown that the degradation of triadimenol in cucumber plants was stereoselective under field conditions. The results indicated that RS enantiomer was degraded faster than SR enantiomer, and SS enantiomer was degraded faster than RR enantiomer, which resulted in plants enriched with SR and RR enantiomers. Furthermore, it was found that leaf was the dominating location for triadimenol enantiomer accumulation and stereoselective degradation, comparing with the root, stem, and fruit tissue.

Direct determination of atrazine residue on Chinese cabbage leaf using desorption electrospray ionization-tandem mass spectrometry and its application for diagnosing atrazine drift phytotoxicity.

A method was developed for the determination of atrazine residue and phytotoxicity on a nontargeted plant, the Chinese cabbage. The analysis was done by desorption electrospray ionization combined with ion trap MS/MS. Within the range of 63.13 to 2525 pg/mm2 of atrazine on the specimen, the linear relationship of the average peak area of extracted product ion m/z 174 (y) versus the surface concentration of atrazine (x) was estimated as y = 5066.5x - 85779; r was 0.9994, with RSD between 3.37 and 26.17%. The LOQ of atrazine on the leaf surface was lower than 63.13 pg/mm2. The method is highly applicable to detect atrazine residue and evaluate atrazine phytotoxicity on Chinese cabbage leaf with good accuracy, selectivity, sensitivity, and specificity.

Study of automated mass spectral deconvolution and identification system (AMDIS) in pesticide residue analysis.

The effects of overlapping levels and concentration ratios of overlapping components, and of scan rates of the mass spectrometer, on the capability of the automated mass spectral deconvolution and identification system (AMDIS) in pesticide residue analysis were studied. To investigate the capability of AMDIS in removing interferences from the overlapping peaks, this system was applied to data files obtained from the gas chromatography/mass spectrometry (GC/MS) analysis of two overlapping (co-eluting) pesticides (beta-HCH and PCNB) in full scan mode. Differences in overlap levels, the concentration ratios of the two overlapping components and the scan rates of the instrument were studied. When the difference in scan number of overlapping compounds was equal to 1 scan, AMDIS incompletely extracted 'purified' mass spectra but as the difference increased to 3 or more scans, complete correct spectra could be extracted. The results also show that when the scan rate was in the range of 0.4-0.90 s/scan and the concentration ratios of the target compound/interference were above 1/5, there were ideal deconvolution results for this approach. To further study the application of AMDIS to pesticide residue analysis, AMDIS was applied to the identification of pesticides spiked in real samples (cabbage and rice). Typical pesticides being evaluated were identified using AMDIS at concentrations >50 ng/g in the extracts.

Simultaneous determination of 109 pesticides in unpolished rice by a combination of gel permeation chromatography and Florisil column purification, and gas chromatography/mass spectrometry.

A multi-residue method is described for the simultaneous analysis of 109 pesticides with different properties in unpolished rice. The range covers organophosphorus, organochlorine, carbamate, and synthetic pyrethroid pesticides. The pesticides were extracted from the sample using ethyl acetate. Most higher molecular weight components such as lipids in the co-extractives were removed by gel permeation chromatography (GPC) with a Bio-bead SX-3 column. A Florisil column with ethyl acetate/hexane as the eluting solvents was used for further cleanup. The pesticides were finally simultaneously determined by gas chromatography/mass spectrometry (GC/MS) in selective ion monitoring (SIM) mode. The average recoveries for most pesticides (spiked level 0.02, 0.1 and 1 microg/g) ranged from 70% to 110%, the relative standard deviation (RSD) was below 20% in every case, and the limit of detection (LOD) varied from 1 to 20 ng/g.