Extraction of eight triazine and phenylurea herbicides in yogurt by ionic liquid foaming-based solvent floatation

Vortex-assisted dispersive liquid-liquid microextraction based on the solidification of sedimentary deep eutectic solvents for the determination of triazine and phenylurea herbicides in milk samples

Vortex-assisted dispersive liquid-liquid microextraction based on the solidification of sedimentary deep eutectic solvents was developed and applied to the extraction of triazine and phenylurea herbicides in milk samples. In this study, a series of novel hydrophobic deep eutectic solvents were prepared using tetrabutylammonium chloride as the hydrogen bond acceptor and perfluorooctanol as the hydrogen bond donor, and their structures, viscosities, densities and melting points were determined. The deep eutectic solvent was used as the extraction solvent and dispersed in the sample solution with the assistance of vortex. After extraction, through centrifugation and subsequent cooling in an ice bath, the deep eutectic solvent was solidified and deposited on the bottom of the centrifuge tube. Subsequently, the deep eutectic solvent combined with the target analytes was diluted and used for chromatographic analysis. Some parameters, including the extraction temperature, type and volume of the deep eutectic solvent, amount of NaCl, vortex time and pH of the sample solution, were optimized by the single-factor experiment, Plackett-Burman design and Box-Behnken design. The limits of detection and quantification were in the range of 0.41-0.59 μg L^-1 and 1.37-1.95 μg L^-1, respectively. The intra-day precision and inter-day precision were in the range of 0.28-2.14% and 2.02-7.99%, respectively. The present method was successfully applied to the determination of triazine and phenylurea herbicides in milk samples.

In-syringe temperature-controlled liquid-liquid microextraction based on solidified floating ionic liquid for the simultaneous determination of triazine and phenylurea pesticide in vegetable protein drinks

A novel in-syringe temperature-controlled liquid-liquid microextraction based on solidified floating ionic liquid (in-syringe TC-LLME-SFIL) combined with high performance liquid chromatography was developed for the simultaneous determination of monuron, chlorotoluron, atrazine, monolinuron, propazine and prometryn in commercial vegetable protein drinks. The samples were deproteinized by trichloroacetic acid and further cleaned up by solid phase extraction column. The ionic liquid tributyldodecylphosphonium tetrafluoroborate ([P_{4 4 4 12}]BF₄) was used as extraction solvent and dispersed into the depurated sample solution to form fine droplets with the assistance of heating and vortex. With the help of an ice bath, the ionic liquid phase solidified and floated on the surface of aqueous phase. After separation from the aqueous phase, the solidified ionic liquids were dissolved with acetonitrile and the resulting solution was analyzed by high performance liquid chromatography. Some extraction parameters, including type and amount of adsorbent, type and amount of ionic liquids, amount of NaCl, melting temperature and time of ionic liquid, vortex time, pH of sample solution, ice bath temperature and time, were investigated and optimized by single-factor experiment, Plackett-Burman design and Box-Behnken design. The results showed that good linearities (r ≥ 0.9994) were obtained in the concentration range of 7.8-1000.0 μg/L. The limits of detection and quantification were in the range of 0.25-2.59 μg/L and 0.82-8.63 μg/L, respectively. The spiked recoveries were 81.26-118.42% with the relative standard deviation (RSD, n = 3) lower than 8.17%. The present method was successfully applied to the simultaneous determination of triazine and phenylurea herbicides in vegetable protein drinks.

Optimization and application of QuEChERS and SPE methods followed by LC-PDA for the determination of triazines residues in fruits and vegetables from Pietermaritzburg local supermarkets

QuEChERS and solid phase extraction (SPE) methods were optimized and applied for the extraction of triazines in fruit and vegetables. These extraction methods are easy, effective, rugged and safe. Also, they have the ability to purify the extracts which leads to lower detection limits and higher recoveries of the analytes. The analysis were conducted using liquid chromatography coupled to photodiode array detector. The limits of detection and quantification ranged from 0.4 -1.4 µg/kg and 1.5 - 4.5 µg/kg, respectively, for QuEChERS and 0.3 - 1.8 µg/kg and 1.4 - 4.9 µg/kg respectively, for SPE. The recoveries ranged from 84 to 102% for QuEChERS and 76-119% for SPE, with relative standard deviation less than 20% for both methods. The fruits and vegetables analysed were apples, pears, carrots, potatoes, tomatoes, avocado, cucumber, spinach, bananas, and oranges. The concentrations detected ranged between 6 and 46 µg/kg in fruits and 4 - 84 µg/kg in vegetables. Simazine was detected in all fruits and vegetable samples except in pear, while terbutylazine was not detected in all samples analysed. Propazine and ametryn were only found in carrot while pear sample only had atrazine. The proposed methods proved to be sensitive and accurate indicating their applicability for detection and monitoring of the selected triazines in fruits and vegetables. However, QuEChERS can be recommended for routine analysis of these triazines due to its fewer extraction steps compared to SPE which is important for turn-around time.

Proteomic analysis of ametryn toxicity in zebrafish embryos

Ametrym (AMT) is the most widely used herbicide and frequently detected in the aquatic environment. AMT also represent a potential health risk to aquatic organisms and animals, including humans. However, little data are available on their toxicity to zebrafish (Danio rerio). The aim of the present study was to evaluate the toxicological effects of AMT exposure on zebrafish embryos. In the acute toxicity test, 6 hpf embryos were exposed to various concentrations of AMT for 24 or 48 h. The results indicated that AMT induced malformation in larvae. To investigate the toxicological mechanism on the protein expression level. A proteomic approach was employed to investigate the proteome alterations of zebra fish embryos exposed to 20 mg/L AMT for 48 h. Among 2925 unique proteins identified, 298 differential proteins (> or <1.3-fold, P < 0.05) were detected in the treated embryos as compared to the corresponding proteins in the untreated embryos. Gene ontology analysis showed that these up-regulated proteins were most involved in glycolysis, lipid transport, protein polymerization, and nucleotide binding, and the down-regulated proteins were related to microtubule-based process, protein polymerization, oxygen transport. Moreover, KEGG pathway analysis indicated that tight junction, ribosome, and oxidative phosphorylation were inhibited in the treated embryos. These findings provide new insight into the mechanisms of toxicity induced by AMT.

Molecularly Imprinted Dispersive Solid-Phase Extraction for the Determination of Triazine Herbicides in Grape Seeds by High-Performance Liquid Chromatography

Molecular imprinting technique, regarded as one of the current state-of-the-art researches, was incorporated with the simple dispersive solid-phase extraction (MI-DSPE) in this work for the extraction of triazine herbicides in grape seeds. The atrazine molecularly imprinted polymers (MIPs) were successfully prepared and characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The imprinting particles were used as the adsorbent in DSPE. Thus, a simple, rapid and selective method based on MIPs coupled with DSPE was established for the simultaneous cleaning-up and quantitative extraction of four triazine herbicides in grape seeds. The experiment parameters, including type of washing solvents, washing time and type of eluting solvents, were investigated and optimized. The performance of the present method was validated by high-performance liquid chromatography. Good linear responses were obtained in concentration range of 0.010-5.0 µg g(-1)with correlation coefficients (r(2)) higher than 0.9993. The recoveries at two spiked levels (1.0 and 2.0 µg g(-1)) were between 81.2 and 113.0% with relative deviations ranging from 1.2 to 10.7%. The limits of detection were ranged between 0.006 and 0.013 µg g(-1), which were lower than the values required by European regulations.

Toxicological evaluation of ametryn effects in Wistar rats

São Paulo state, Brazil, is one of the main areas of sugar cane planting in the world. Extensive use of ametryn, a triazine herbicide, in sugar cane agriculture and the properties of this herbicide suggest it could be present in the environment as a potential contaminant of soil, surface water, groundwater, and river sediment. In order to clarify the mechanism through which ametryn could be toxic, an in vivo study with Wistar rats was conducted using hematological, biochemical, molecular, morphological and genotoxic approaches. For this purpose, two sub-lethal ametryn concentrations (15 mg and 30 mg/kg/day) were administered to 42 rats divided into three groups (n=12) by gavage during 56 days, whereupon blood, liver and bone marrow were collected. The results showed ametryn genotoxic activity by in vivo micronuclei testing. This event probably occurred as consequence of oxidative stress induction demonstrated by GSTM1 transcript levels increase (indicating complexation between ametryn and/or metabolites with GSH) and by SOD activity decrease. Also, Mn-SOD transcripts were increased, probably avoiding mtDNA damage caused by EROS. These mechanisms displayed hepatic stellate cell (HSCs) activation because two major biomarkers were regulated, connexin and cadherin. N-cad transcripts were increased on both exposed groups while E-cad decreased in the T1 group, indicating epithelial-to-mesenchymal transition. In addition, Cx43 transcripts were decreased suggesting an increase in collagen content. Volumetric proportion of sinusoids was significantly decreased in T1 group and no significant alteration in hepatocyte volume was observed, indicating an increase in the space of Disse, due to fibrosis. Hepatocyte nuclei showed significant decrease in diameter and volume. Few hematological alterations were found. We emphasize the importance of other approaches, such as cell death and proliferation assays, so that ametryn toxicity can better be understood.

Leydig cell number and sperm production decrease induced by chronic ametryn exposure: a negative impact on animal reproductive health

Ametryn is an herbicide used to control broadleaf and grass weeds and its acute and chronic toxicity is expected to be low. Since toxicological data on ametryn is scarce, the aim of this study was to evaluate rat reproductive toxicity. Thirty-six adult male Wistar rats (90 days) were divided into three groups: Co (control) and T1 and T2 exposed to 15 and 30 mg/kg/day of ametryn, respectively, for 56 days. Testicular analysis demonstrated that ametryn decreased sperm number per testis, daily sperm production, and Leydig cell number in both treated groups, although little perceptible morphological change has been observed in seminiferous tubule structure. Lipid peroxidation was higher in group T2, catalase activity decreased in T1 group, superoxide dismutase activity diminished, and a smaller number of sulphydryl groups of total proteins were verified in both exposed groups, suggesting oxidative stress. These results showed negative ametryn influence on the testes and can compromise animal reproductive performance and survival.

Determination of picogram quantities of chlortoluron in soil samples by luminol-chitosan chemiluminescence system

Based on the enhancing effect of chitosan (CS) on luminol-dissolved oxygen chemiluminescence (CL) reaction, a flow injection (FI) luminol-CS CL system was established. It was found that the increase of CL intensity was proportional to the concentrations of CS ranging from 0.7 to 10.0 μmol l(-1). In the presence of chlortoluron (CTU), the CL intensity of luminol-CS system could be obviously inhibited and the decrements of CL intensity were linearly proportional to the logarithm of CTU concentrations ranging from 0.01 to 70.0 ng ml(-1), giving the limit of detection 3.0 pg ml(-1) (3σ). At a flow rate of 2.0 ml min(-1), the whole process including sampling and washing could be accomplished within 36 s, offering a sample throughput of 100 h(-1). The proposed FI-CL method was successfully applied to the determination of CTU in soil samples with recoveries ranging from 95.0 % to 105.3 % and the relative standard deviations (RSDs) of less than 4.0 %.