Fast determination of phenoxy acid herbicides in carrots and apples using liquid chromatography coupled triple quadrupole mass spectrometry

A fast, simple and inexpensive method has been developed for the analysis of phenoxy acid herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(4-chloro-o-tolyloxy)propionic acid (MCPP), 2-(4-aryloxyphenoxy)propionic acid (Fluazifop) and 2-(4-aryloxyphenoxy)propionic acid (Haloxyfop) in carrots and apples by liquid chromatography coupled to triple quadrupole mass spectrometry (LC/MS/MS). The compounds were analyzed by QuEChERS (quick, easy, cheap, effective, rugged, safe) methodology without cleanup.

The recoveries were performed at two spiked levels (0.05 and 0.5 mg/kg) for both matrices with six replicates for each level. The mean recoveries ranged from 70–92% for both apples and carrots. The precision of the method expressed as relative standard deviation (RSD%) was found to be in the range 3–15%. For all compounds, good linearity (r² > 0.99) was obtained over the range of concentration from 0.05 μ g/mL to 0.5 μ g/mL, corresponding to the pesticide concentrations of 0.05 mg/kg and 0.5 mg/kg, respectively. The determination limits (LOQs) ranged from 0.01 ng/mL to 1.3 ng/mL in solvent, whereas, the LOQs calculated in matrix ranged from 0.05 ng/g to 21.0 ng/g for apples and from 0.06 ng/g to 10.2 ng/g for carrots. The developed methodology combines the advantages of both QuEChERS and LC/MS/MS producing a very rapid, sensitive and cheap method useful for the routine analytical laboratories.     

Impact of Sublethal Doses of 2,4-D,Simulating Drift,on Tomato Yield

Abstract

Tomato is considered one of the most sensitive crops regarding 2,4-D drift. In many cases, such susceptibility has led to important restrictions in the use of 2,4-D based products. Field experiments were carried out for two consecutive years in tomato, by applying sublethal doses of 2,4-D (ranging from 0.42 to 13.44 g a.i. ha^?1) directly to plants, at different stages of growth, as a simulation of eventual drifts to the crop. The range of rates was based on the assumption of a 0.0625–2.0% drift level of a 1 L ha^?1 of the most common formulated herbicides. For this crop, the range of rates between 0.42 and 13.44 g a.i ha^?1 applied at the beginning of flowering caused a linear crop reduction. On the other hand, rates ≤13.44 g a.i. ha^?1 applied after full development of fourth truss stage or latter had no effect on crop yield or development. For tomato, tolerance to 2,4-D strongly increases with plant age.     

Spiking solvent, humidity and their impact on 2,4-D and 2,4-DCP extractability from high humic matter content soils

The 2,4-dichlorophenoxyacetic acid (2,4-D) is a hormone-like herbicide widely used in agriculture. Although its half life in soil is approximately two weeks, the thousands of tons introduced in the environment every year represent a risk for human health and the environment. Considering the toxic properties of this compound and its degradation products, it is important to assess and monitor the 2,4-D residues in agricultural soils. Furthermore, experiments of phyto/bioremediation are carried out to find economic and environmental friendly tools to restore the polluted soils. Accordingly, it is essential to accurately measure the amount of 2,4-D and its metabolites in soils. There is evidence that 2,4-D extraction from soil samples seriously depends on the physical and chemical properties of the soil, especially in those soils with high content of humic acids. The aim of this work was to assess the variables that influence the recovery and subsequent analysis of 2,4-D and its main metabolite (2,4-dichlorophenol) from those soils samples. The results showed that the recovery efficiency depends on the solvent and method used for the extraction, the amount and kind of solvent used for dissolving the herbicide and the soil water content at the moment of spiking. An optimized protocol for the extraction and quantification of 2,4-D and its main metabolite from soil samples is presented.     

磺酰脲类除草剂在环境中的光降解研究——水溶液中的光解动力学

以汞灯为光源,研究了甲黄隆,苯黄隆,氯黄隆,氯嘧黄隆,苄嘧黄和胺苯黄隆６种磺酰脲类除草剂在水液中的光解动力淡。结果表明,５种磺酰的降解呈一级动力学反应;体系的ＰＨ值对降解速率影响不明显,光强的影响较明显著;Ｈ２Ｏ２丙酮和溶解有机质均可促进磺酰光解;党妥氧对该类除草剂光解的影响表现为光氧化与淬灭２种作用的竞争。     

磺酰脲类除草剂研究进展

本文较全面地概述了近几年国内外有关磺酰脲类除草剂的分析测试和降解方式等方面的研究现状,着重讨论了磺酰脲类化合物的结构活性相关和风险评价等方面的研究进展     

固相萃取-高效液相色谱法同时测定水中12种磺酰脲类除草剂

采用固相萃取-高效液相色谱法同时测定水中12种磺酰脲类除草剂,样品经磷酸调节pH值为2后,经Watens Oasis HLB SPE柱净化浓缩,乙腈洗脱,选择检测波长为230 nm,以乙腈-水溶液(0.02%磷酸)为流动相梯度洗脱,保留时间在14 min～32 min范围内.12种磺酰脲类除草剂在0.050 mg/L～...     

Ability of Poplar (Populus spp.) to Detoxify Chloroacetanilide Herbicides

The ability of poplar trees to resist chemical stress caused by chloroacetanilide herbicides was studied. Detached leaves of Lombardy poplar (Populus nigra L.) were exposed to seven chloroacetanilide herbicides via uptake through the cut petiole. The leaves showed high tolerance against the phytotoxicity of these compounds. Their tolerance was further enhanced by treatment with 2-oxothiazolidine-4-carboxylic acid (OTC, a precursor of the amino acid cysteine). High levels of glutathione (GSH) and GSH S-transferase (GST) activity were detected in poplar leaves. Treatments with chloroacetanilide herbicides left the GSH content in the leaves unchanged but strongly induced the GST activity. In contrast, in OTC-treated leaves increased GSH contents were measured, but GST activities remained unchanged. It therefore appears that a highly active and inducible GSH-conjugation Phase II detoxification system in their leaves may make poplar trees useful for phytoremediation of soils contaminated with chloroacetanilide herbicides. Based on these findings a phytoremediation project using different poplar hybrids at a site heavily polluted with such compounds in Hungary has been launched.     

Absorption and translocation of sulfometuron-methyl in sugarcane (Saccharum officinarum L.) at different growth stages

ABSTRACT

In Brazil, weed management in sugarcane fields is mainly done with the use of selective herbicide formulations. For many years, diuron+hexazinone was one of the main herbicide mixture formulations used in sugarcane. Later, sulfometuron-methyl was included in the same mixture, which was marketed as a new herbicide formulation for residual in-season weed control in sugarcane. The mixture diuron+hexazinone+sulfometuron-methyl has been widely used in commercial sugarcane fields in Brazil. However, recent field observations have shown that sugarcane plants at different growth stages varied in their phytotoxicity levels after treatment with diuron+hexazinone+sulfometuron-methyl. Greenhouse and laboratory studies were conducted to determine ¹⁴Csulfometuron-methyl absorption and translocation, as well as ¹⁴C distribution in sugarcane at two growth stages, 2 to 3 leaves and 5 to 6 leaves. ¹⁴Csulfometuron-methyl absorption by sugarcane did not differ between the two growth stages. Different patterns of ¹⁴C accumulation were observed, which may explain variations in sulfometuron-methyl phytotoxic responses observed in the field.     

Responses of different fungal and plant species to acetolactate synthase inhibitors and their derivatives

Abstract

The effect of sulfonylurea (SU) acetolactate synthases (ALS) inhibitors (chlorsulfuron and triasulfuron) and their 13 guanidine and 7 azole derivatives was studied on 17 fungal and 21 plant species. The efficacy of chlorsulfuron and triasulfuron against Fusarium oxysporum and Thielaviopsis basicola was higher than carbendazim. Two azole derivatives were highly selective for maize. The antifungal activity spectrum of both guanidine and azole derivatives differed from that of chlorsulfuron and triasulfuron, and did not exert notable antifungal activity in vitro. However, they had significant anti‐Fusarium efficacy on rye that surpassed that of carbendazim.     

THE EFFECTS OF DIPOTASSIUM ENDOTHALL ON THE ZOOPLANKTON AND WATER QUALITY OF A SMALL POND1

ABSTRACT: Zooplankton samples and dissolved oxygen-temperature readings and water samples were taken from a treatment and control pond on 41 and 42 separate occasions, respectively, both before and after the application of 5.0 mg/l (a.i.) dipotassium endothall to the 0.31 ha treatment pond on May 31, 1973. Seasonal fluctuations in the density of Cladocera and Copepoda coincided quite closely in both ponds and were similar to the fluctuations reported in the literature to be typical of temperate region ponds and lakes. An apparent seasonal shift in generic composition from .Daphnia spp. in May to Ceriodaphnia spp. in June to Chydorus spp. from July/early September occurred in both ponds and is thought to be at least partially due to fish predation. No apparent changes in species composition or generic densities of Cladocerans was noted in the treatment pond that did not also occur in the control pond. There were no noticeable effects of the dipotassium endothall on either the Calanoida or Cyclopoida suborders of Copepoda. A later pulse of Ostracoda in the treatment pond, when compared to the control, may have been due to the dipotassium endothall or to a combination of the effects of the herbicide on the macrophytes and the method of sampling. A decrease in dissolved oxygen below saturation, occurring in the treated pond from 3–21 days after treatment, was attributed to an increase in biological oxygen demand associated with weed-kill. There was no noticeable increase in plant nutrients (N and P) in the treated pond following herbicide application, nor were there any apparent changes in the other chemical parameters studied.