Soil dissipation and biological activity of metolachlor and S-metolachlor in five soils

The resolved isomer of metolachlor, S-metolachlor, was registered in 1997. New formulations based primarily on the S-metolachlor isomer are more active on a gram for gram metolachlor basis than formulations based on a racemic mixture of metolachlor containing a 50:50 ratio of the R and S isomers. The labelled use rates of S-metolachlor-based products were reduced by 35% to give equivalent weed control to metolachlor. However, several companies have recently registered new metolachlor formulations with the same recommended use rates for weed control as S-metolachlor. This research was done to compare the soil behaviour and the biological activity of metolachlor and S-metolachlor in different soils under greenhouse and field conditions. Although K(d) ranged from 1.6 to 6.9 across the five soils, there were no differences in the binding of metolachlor and S-metolachlor to soil or in the rate of soil solution dissipation in a given soil. However, both greenhouse and field studies showed that S-metolachlor was 1.4-3-fold more active than metolachlor against Echinochloa crus-galli (L.) Beauv. in five different soils and that S-metolachlor was more active than metolachlor in three Colorado field locations. When the rates of metolachlor and S-metolachlor were adjusted for S isomer concentrations in the formulations, there were no differences between the formulations in field, greenhouse or bioassay studies. Thus herbicidal activity is due to the S isomers, with the R isomers being largely inactive.     

Adsorption,desorption and dissipation of metolachlor in surface and subsurface soils

BACKGROUND: Variations in soil properties with depth influence retention and degradation of pesticides. Understanding how soil properties within a profile affect pesticide retention and degradation will result in more accurate prediction by simulation models of pesticide fate and potential groundwater contamination. Metolachlor is more persistent than other acetanilide herbicides in the soil environment and has the potential to leach into groundwater. Reasonably, information is needed about the dissipation and eventual fate of metolachlor in subsoils. The objectives were to evaluate the adsorption and desorption characteristics and to determine the dissipation rates of metolachlor in both surface and subsurface soil samples. RESULTS: Adsorption of metolachlor was greater in the high‐organic‐matter surface soil than in subsoils. Lower adsorption distribution coefficient (K_ads) values with increasing depth indicated less adsorption at lower depths and greater leaching potential of metolachlor after passage through the surface horizon. Desorption of metolachlor showed hysteresis, indicated by the higher adsorption slope (1/n_ads) compared with the desorption slope (1/n_des). Soils that adsorbed more metolachlor also desorbed less metolachlor. Metolachlor dissipation rates generally decreased with increasing soil depth. The first‐order dissipation rate was highest at the 0–50 cm depth (0.140 week^?1) and lowest at the 350–425 cm depth (0.005 week^?1). Degradation of the herbicide was significantly correlated with microbial activity in soils. CONCLUSION: Metolachlor that has escaped degradation or binding to organic matter at the soil surface might leach into the subsurface soil where it will dissipate slowly and be subject to transport to groundwater. Copyright © 2009 Society of Chemical Industry     

Sorption of aged dicamba residues in soil

The effect of aging (residence time in soil) on dicamba (3,6-dichloro-2-methoxybenzoic acid) and a major metabolite, 3,6-dichlorosalicylic acid (3,6-DCSA) sorption was determined in an unamended and a carbon-amended sandy loam and in a silt loam soil. During the incubation, sequential solvent extraction with 0.01 M calcium chloride solution and aqueous acetonitrile + hydrochloric acid was used to determine the solution and sorbed concentrations of dicamba and 3,6-DSCA, and sorption coefficients were calculated. Dicamba was weakly sorbed to soil (Kd < 0.7). In contrast to some other classes of pesticides, sorption of dicamba did not significantly increase with aging, at least not until < 15% of the applied dicamba remained. 3,6-DSCA was strongly sorbed to soil (Kd > 8) and the Kd-a value increased by a factor of 2-6 during a 28-day aging period. Addition of a carbon source to the soil had minimal effect on the strength of sorption of aged dicamba. However, it did appear to decrease 3,6-DSCA availability to soil micro-organisms; once formed 3,6-DSCA was not further mineralized. While it appears that sorption can be well characterized for weakly sorbed pesticides using the batch equilibration method with freshly treated soils, this procedure may not be adequate for more strongly sorbed pesticides and their degradates.     

Influence of soil pH-sorption interactions on the carry-over of fresh and aged soil residues of imazamox

Long-term carry-over of some imidazolinone herbicides has been observed in soil that is below pH 6.5, resulting in significant damage to sugarbeet. In a field study in south-west Minnesota, imazamox concentration decreased rapidly in soil, regardless of pH. Despite similar amounts of aged soil residues of imazamox remaining at different pH levels, bioavailability differed with pH as a result of pH effects on sorption–desorption interactions. At low pH, more imazamox was sorbed than at high pH, but it was readily desorbed. At high pH, less imazamox was sorbed initially, but it did not readily desorb. Thus, after 3 months, the remaining imazamox in low-pH soil was desorbable and bioavailable, resulting in injury to oilseed rape and sugarbeet. In aged, low-pH soil, adding lime released bound imazamox, which was then degraded, resulting in less carry-over.     

Sorption-desorption of flucarbazone and propoxycarbazone and their benzenesulfonamide and triazolinone metabolites in two soils

Sorption-desorption interactions of pesticides with soil determine the availability of pesticides in soil for transport, plant uptake and microbial degradation. These interactions are affected by the physical and chemical properties of the pesticide and soil and, for some pesticides, their residence time in the soil. While sorption-desorption of many herbicides has been characterised, very little work in this area has been done on herbicide metabolites. The objective of this study was to characterise sorption-desorption of two sulfonylaminocarbonyltriazolinone herbicides, flucarbazone and propoxycarbazone, and their benzenesulfonamide and triazolinone metabolites in two soils with different physical and chemical properties. K(f) values for all four chemicals were greater in clay loam soil, which had higher organic carbon and clay contents than loamy sand. K(f-oc) ranged from 29 to 119 for the herbicides and from 42 to 84 for the metabolites. Desorption was hysteretic in every case. Lower desorption in the more sorptive system might indicate that hysteresis can be attributed to irreversible binding of the molecules to soil surfaces. These data show the importance of characterisation of both sorption and desorption of herbicide residues in soil, particularly in the case of prediction of herbicide residue transport. In this case, potential transport of sulfonylaminocarbonyltriazolinone herbicide metabolites would be overpredicted if parent chemical soil sorption values were used to predict transport.     

Adsorption-desorption studies of alachlor, metolachlor, EPTC, chlorothalonil and pirimiphos-methyl in contrasting soils

Five soils with different organic matter contents ranging from 0.48 to 10.4% were used to study the adsorption and desorption of alachlor, metolachor, EPTC, chlorothalonil and pirimiphos-methyl in batch experiments. The isotherm shapes according to Giles classification were S-type for alachlor, metolachlor and chlorothalonil, changing to L-type for the latter as the level of soil organic matter increased, and L-type for EPTC and pirimiphos-methyl. The adsorption isotherms fitted the Freundlich equation x/m = KfCe1/n. The Kf values increased with the increase of organic matter content. The amounts of pesticides adsorbed over a range of concentrations of 0.1-20 mg litre-1 reached 63.1% for alachlor, 69.2% for metolachlor, 89.3% for EPTC, 98.4% for chlorothalonil and 96.3% for pirimiphos-methyl. The increase of the amounts desorbed with acetone indicated that the sorption of organic compounds onto organic matter occurred principally via weak London-type induction forces, or dispersion forces which are characteristics of the physical adsorption process.     

乙嘧酚在苹果中的残留及消解动态

采用乙腈提取、固相萃取法净化和高效液相色谱(HPLC-UV)检测方法,研究了乙嘧酚在苹果中的消解动态及最终残留。结果表明:采用70%甲基硫菌灵(50%)·乙嘧酚(20%)可湿性粉剂,在乙嘧酚有效成分为525 mg/kg剂量下对苹果植株喷雾施药,2010和2011年乙嘧酚在苹果中的半衰期(t1/2)分别为1.94~2.65 d和2.07~2.70 d;在525 mg/kg剂量下施药4次,间隔期10 d,距第4次施药后7 d时,乙嘧酚在苹果中的最终残留量低于最低检测浓度(0.02 mg/kg),远低于欧盟规定的最大残留限量值(0.1 mg/kg)。     

Sorption and leaching potential of herbicides on Brazilian soils

Sorption of the herbicides alachlor, atrazine, dicamba, hexazinone, imazethapyr, metsulfuron-methyl, nicosulfuron, simazine and sulfometuron-methyl was characterized on six Brazilian soils, using the batch equilibration method. In general, weak acid herbicides (dicamba, imazethapyr, metsulfuron-methyl, nicosulfuron and sulfometuron-methyl) were the least sorbed, whereas weak bases such as triazines and nonionic herbicides (alachlor) were the most sorbed. The Kd values found showed a significant correlation with soil organic carbon content (OC) for all herbicides except imazethapyr and nicosulfuron. Koc values showed a smaller variation among soils than Kd . To estimate the leaching potential, Koc and the ground-water ubiquity score (GUS) were used to calculate half-lives ( t_1/2 ) that would rank these herbicides as leachers or non-leachers. Comparison of calculated values to published values for t_1/2 demonstrated that sulfonylureas and hexazinone are leachers in all soils, alachlor is transitional, and atrazine, simazine and dicamba are leachers or transitional, depending on soil type. Results discussed in this paper provide background to prioritize herbicides or chemical groups that should be evaluated in field conditions with regard to their leaching potential to ground-water in tropical soils.     

Characterization of triadimefon sorption in soils using supercritical fluid (SFE) and accelerated solvent (ASE) extraction techniques

Sorption–desorption of the fungicide triadimefon in field‐moist silt loam and sandy loam soils were determined using low‐density supercritical fluid extraction (SFE). The selectivity of SFE enables extraction of triadimefon from the soil water phase only, thus allowing calculation of sorption coefficients (K_d) at field‐moist or unsaturated conditions. Triadimefon sorption was influenced by factors such as soil moisture content and temperature; sorption increased with increased moisture content up to saturation, and decreased with increased temperature. For instance, K_d values for triadimefon on the silt loam and the sandy loam soils at 40 °C and 10% water content were 1.9 and 2.5 ml g⁻¹, respectively, and at 18% water content, 3.3 and 6.4 ml g⁻¹, respectively. Isosteric heats of sorption (ΔH_i) were −42 and −7 kJ mol⁻¹ for the silt loam and sandy loam soils, respectively. Sorption–desorption was also determined using an automated accelerated solvent extraction system (ASE), in which triadimefon was extracted from silt loam soil by 0.01 M CaCl₂. Using the ASE system, which is basically a fast alternative to the batch equilibration system, gave a similar ΔH_i value (−29 kJ mol⁻¹) for the silt loam soil (K_f = 27 µg^{1 − 1/n} ml^1/n g⁻¹). In order to predict transport of pesticides through the soil profile more accurately on the basis of these data, information is needed on sorption as a function of soil water content. © 2000 Society of Chemical Industry     

Degradation kinetics and safety evaluation of buprofezin residues in grape (Vitis vinifera L.) and three different soils of India

BACKGROUND: This work was undertaken to determine the preharvest interval (PHI) of buprofezin to minimize its residues in grapes and thereby ensure consumer safety and avoid possible non‐compliance in terms of residue violations in export markets. Furthermore, the residue dynamics in three grapevine soils of India was explored to assess its environmental safety. RESULTS: Residues dissipated following non‐linear two‐compartment first + first‐order kinetics. In grapes, the PHI was 31 days at both treatments (312.5 and 625 g a.i. ha^?1), with the residues below the maximum permissible intake even 1 h after foliar spraying. Random sampling of 5 kg comprising small bunchlets (8–10 berries) collected from a 1 ha area gave satisfactory homogeneity and representation of the population. A survey on the samples harvested after the PHI from supervised vineyards that received treatment at the recommended dose showed residues below the maximum residue limit (MRL) of 0.02 mg kg^?1 applicable for the European Union. In soil, the degradation rate was fastest in clay soil, followed by sandy loam and silty clay, with a half‐life within 16 days in all the soils. CONCLUSION: The recommendation of the PHI proved to be effective in minimizing buprofezin residues in grapes. Thus, this work is of high practical significance to the domestic and export grape industry of India to ensure safety compliance in respect of buprofezin residues, keeping in view the requirements of international trade. Copyright © 2008 Society of Chemical Industry     

二氰蒽醌和吡唑醚菌酯在苹果中的残留及消解动态

建立了超高效液相色谱-二极管阵列检测器检测二氰蒽醌和吡唑醚菌酯在苹果中残留量的分析方法,并对2种农药在苹果中的消解动态及最终残留量进行了研究。结果表明:在0.1~5 mg/kg添加水平下,二氰蒽醌和吡唑醚菌酯在苹果中的平均回收率为72%~98%,相对标准偏差为2.0%~9.7%;2种农药在苹果中的定量限均为0.1 mg/kg。二氰蒽醌和吡唑醚菌酯在苹果中的消解半衰期分别为3.0~6.5 d和13.5~23.6 d。采用16%唑醚·氰蒽醌水分散粒剂对水施药有效成分质量浓度为0.43和0.64 g/L,分别施药3~4次,距最后一次施药21 d时,苹果中二氰蒽醌残留量为 < 0.1~0.80 mg/kg,吡唑醚菌酯残留量为 < 0.10~0.34 mg/kg,均低于中国国家标准中规定的苹果中二氰蒽醌和吡唑醚菌酯最大残留限量值5.0 mg/kg和0.5 mg/kg。建议采用16%唑醚·氰蒽醌水分散粒剂在苹果上的最大施药剂量为有效成分质量浓度0.43 g/L,施药间隔期7 d,最多施药3次,安全间隔期为21 d。     

氟环唑在小麦及土壤中的残留及消解动态

为了评价氟环唑在小麦生产上使用的残留安全性,建立了气相色谱-电子捕获检测器检测氟环唑在小麦植株、小麦籽粒及土壤中残留的分析方法,并对氟环唑在小麦植株、小麦籽粒和土壤中的最终残留量及小麦植株和土壤中的消解动态进行了研究。结果表明:在添加水平为0.01、0.1和2 mg/kg（小麦籽粒和土壤）和0.01、0.1和10 mg/kg（小麦植株）下,氟环唑的回收率为82%~93%,相对标准偏差为3.0%~9.7%。氟环唑在小麦植株、小麦籽粒和土壤中的定量限均为0.01 mg/kg。氟环唑在小麦植株和土壤中的消解半衰期分别为3.5~8.4和10~30 d。当以有效成分112.5 g/hm2的剂量施药2次、采收间隔期为21 d时,小麦籽粒中氟环唑的残留量为<0.05 mg/kg,低于中国制定的小麦中氟环唑的最大残留限量值（0.05 mg/kg）。建议氟环唑在小麦上使用时最大剂量为有效成分112.5 g/hm2,施药2次,安全间隔期为21 d。     

Sorption of isoxaflutole by five different soils varying in physical and chemical properties

Isoxaflutole is a new pre-emergence corn herbicide which controls both grass and broadleaf weeds. Experiments were performed in the laboratory to study the sorption of isoxaflutole in five different soils (Moorhead, MN; East Monroe, CO; Ellendale, MN; South Deerfield, MA; and Chelsea, MI) using the batch equilibration technique. Total initial isoxaflutole solution concentrations for each soil were 0.05, 0.15, 0.3. 0.8, 1.5, 2.0 and 4.0 mg litre⁻¹. Analysis of [ring-¹⁴C] isoxaflutole was performed using liquid scintillation counting, and sorption data were fitted with the Freundlich model. Isotherms of isoxaflutole in all the soils were non-linear as depicted by the exponent (n < 1.0), indicating differential distribution of sorption site energies in various soils. Since the isotherms were non-linear the data fit Freundlich's isotherm well, as was indicated by high values of the regression coefficient (r²). The Freundlich sorption coefficient ranged from 0.555 to 50.0 (litre ⁿmg ^l−nkg⁻¹). Multiple regression of the sorption constant, K_F against selected soil properties indicated that organic matter content was the best single predictor of isoxaflutole sorption (r² = 0.999) followed by soil pH (r² = 0.954). Clay content of the soils did not have a high correlation with K_F values (r² = 0.453), while the sorption of isoxaflutole was not influenced by the Ca²⁺ concentration in the soil solution. Isoxaflutole sorption increased with an increase in organic matter content of soils. Sorption of isoxaflutole decreased as the soil pH increased from 4.5 to 8.5, which was depicted by the reduction of K_F values. Sorption of isoxaflutole to the soils varied with differences in binding energies. At a particular net energy value (E*), the corresponding site energy distribution [F(E*)] values followed the order, Chelsea, MI > Moorhead, MN > East Monroe, CO > South Deerfield, MA > Ellendale, MN. The negative magnitude of Gibbs free energy of sorption (ΔG ^x) indicates the spontaneity of the given sorption process in the soils from Moorhead, MN; East Monroe, CO and Chelsea, MI. © 1999 Society of Chemical Industry     

Analysis,sorption and residues of a homologous series of isothiocyanates on wheat

A series of isothiocyanates (R-NCS, R, 1–6 carbon atoms) was applied in the vapour phase to wheat in sealed containers. The speed of sorption, as measured by the rate of loss from the intergranular air space, was inversely proportional to molecular weight; e.g. the time for 50% sorption of hexyl isothiocyanate was over 100 times longer than for the methyl analogue. Despite extensive sorption, most of the applied chemicals was recovered from the fumigated wheat seven days after dosing, indicating that sorption did not lead to extensive degradation. Purge and trap techniques proved suitable for recovery of low-boiling, but not high-boiling chemicals.     

Sorption of atrazine and dicamba in Delaware coastal plain soils: a comparison of soil thin layer and batch equilibrium results

The mobility and retention of atrazine and dicamba in six Atlantic Coastal Plain soils were estimated by soil thin-layer chromatography (soil-TLC). The soils studied were representative of the major agricultural regions in Delaware and were sampled, by horizon, to the water table. Four horizons from each profile were leached simultaneously with distilled water on one soil-TLC plate. Two values were obtained from each plate: the ratio of the distance traveled by the herbicide center of mass over that traveled by the solvent front (R_m), and a sorption distribution coefficient (K_d). The R_m values ranged from 0·06 to 0·94 for atrazine and from 0·80 to 0·94 for dicamba. Herbicide mobility was found to be greatest in coarse-textured soil horizons that contained low levels of organic matter, clay, and Fe and Al oxides. Correlation analysis indicated that effective cation exchange capacity, exchangeable acidity, exchangeable aluminum, and clay were useful predictive variables or both atrazine mobility and sorption. Organic matter was not useful for predicting soil-TLC derived sorption estimates; however, it was correlated to K_d-batch estimates. Distribution coefficients calculated from soil-TLC data were found to be in general agreement with K_d values obtained for the same soils by batch equilibrium techniques. The average K_d-soil-TLC values for atrazine and dicamba were 2·09(±2·24) and 0·03(±0·02), respectively. The ratio of the batch K_d to the soil-TLC K_d ranged from 0·1 to 19 (x̄=1·6, SD=3·8) for atrazine and from 2·9 to 38 (x̄=12·6, SD=8·7) for dicamba. Thus, although for some horizons agreement between the two methods was good, for other horizons significant discrepancies existed. It is suggested that the soil-TLC gives results under non-equilibrium conditions, whereas the batch procedure is, by definition, at quasi-equilibrium. These fundamental differences may account for the observed differences between the two methods. It is also suggested that, due to this difference, the soil-TLC procedure can provide additional information relevant to herbicide partitioning in the field environment that is not provided by traditional batch equilibrium techniques. © 1998 Society of Chemical Industry     

Laboratory studies on formation of bound residues and degradation of propiconazole in soils

Laboratory studies on the formation of bound residues and on the degradation of the triazole fungicide propiconazole were conducted in two different soils. Soils treated with 14C-propiconazole were incubated at 22 degrees C and extracted exhaustively with a solvent at each sampling date until no further propiconazole was extracted. The solvent-extractable residues were used to measure propiconazole remaining in the soil, and the extracted soils were used to investigate bound residues of propiconazole. Mineralization of propiconazole was investigated by measuring [14C]carbon dioxide evolved from the soil samples. Formation of bound residues of propiconazole was higher in silty clay loam soil than in sandy loam soil, giving approximately 38 and 23% of the applied 14C, respectively. In contrast, the rates of degradation and mineralization of propiconazole were lower in silty clay loam soil than in sandy loam soil. Decreased extractability of the 14C residues with incubation time was observed with increased formation of bound residues. When the propiconazole remaining in the solvent-extractable residues was quantitatively measured by high-pressure liquid chromatographic analysis, the half-life value in sandy loam soil was about 315 days, while the half-life in silty clay loam soil exceeded the duration of the 1 year experimental period. Increased formation of bound residues was observed as propiconazole degraded with incubation time, suggesting that degradation products are involved in the formation of bound residues. Our study suggests that the formation of bound residues of propiconazole contributes to the persistence of this fungicide in soil.     

阿维菌素在3种十字花科蔬菜中的残留消解动态

为探明阿维菌素在十字花科蔬菜芥蓝、叶芥菜和芜菁中的残留消解行为和安全性,建立了高效液相色谱测定3种蔬菜中阿维菌素残留量的分析方法。样品经丙酮提取,C18柱净化,高效液相色谱-紫外检测器检测,外标法定量;运用所建立的方法对阿维菌素在山东烟台、河北保定、浙江绍兴、贵州贵阳、黑龙江哈尔滨和安徽宿州6个试验点的芥蓝、叶芥菜、芜菁中的残留消解动态和最终残留量进行了研究。结果表明:阿维菌素在芥蓝、叶芥菜和芜菁中的消解速率很快,半衰期分别为0.3~0.6、2.2~3.1和0.8~1.0 d,其残留量随时间延长而递减,符合一级反应动力学方程,属易消解型农药。     

噻菌茂在稻田土壤中的微生物降解及对土壤细菌种群数量的影响

采用模拟土壤生态系统,研究了噻菌茂(2-苯甲酰肼-1,3-二噻茂烷)在不同稻田土壤中的消解规律及其对土著细菌种群数量的影响。结果表明,0.2和100 mg/kg的噻菌茂在未灭菌处理的淹水及不淹水土壤中的消解半衰期分别为2.6、4.0 d和5.5、7.3 d,而在经灭菌处理未淹水土壤中的消解半衰期分别为7.5和11.0 d,表明微生物是土壤中噻菌茂消解的主要影响因子。同时,噻菌茂对土壤中的微生物尤其是稻田土壤细菌也具有一定的影响,低浓度(0.2 mg/kg)下,噻菌茂对土壤中细菌生长的影响是暂时性的,7 d后菌群生长即可基本恢复至对照水平;而高浓度(100 mg/kg)噻菌茂则对土壤中细菌的生长具有明显的持续抑制作用,28 d后菌群生长仍未能恢复。     

Measuring cysteine biosynthesis activity from serine in extracts from sorghum, corn and grass weeds, and their metolachlor susceptibility

In vitro assay procedures for measuring the activity of cysteine biosynthesis from serine (CBS), which is a coupled reaction catalyzed by serine acetyltransferase and cysteine synthase, were developed using crude extracts from sorghum shoots. Cysteine biosynthesis from serine activity was dependent on acetyl‐CoA concentrations (up to 1.5 mmol L^?1), serine (at least up to 20 mmol L^?1) and sulfide (up to 0.25 mmol L^?1), respectively, and was proportional to the protein concentration in the reaction mixture below 0.4 mg mL^?1. The reaction rate was 6.6 nmol min^?1 per mg of protein during the first 5 min, but increased to 45.6 nmol min^?1 per mg of protein between 30 and 45 min after reaction initiation. Sorghum had the highest CBS total activity (222.4 nmol min^?1 per g of fresh weight), and large crabgrass had the lowest CBS total activity (4.7 nmol min^?1 per g of fresh weight) when CBS activity in shoots was extracted from sorghum, corn, johnsongrass, barnyardgrass, goosegrass, green foxtail and large crabgrass. Similar results were obtained for CBS specific activity (nmol min^?1 per mg of protein). There was no correlation between total CBS activity and susceptibility to metolachlor; however, when corn was excluded, a correlation of R² = 0.690 was found. Flurazole seed treatment (1.25 g per kg of seed) conferred metolachlor resistance by sorghum, and enhanced total CBS activity and non‐protein thiol content by 27 and 61%, respectively. The increase in thiol content presumably contributed to metolachlor tolerance in sorghum. From these results, the difference in CBS activity partially contributes to the selectivity to metolachlor among certain grass species, and to the safening action of flurazole by increasing thiol content.     

气相色谱-串联质谱法快速检测玉米粉中乙草胺、异丙甲草胺和三唑酮残留

建立了玉米粉中乙草胺、异丙甲草胺和三唑酮残留检测的气相色谱-串联质谱(GC-MS/MS)分析方法。样品采用乙腈浸提3 h、过两次0.22μm尼龙66微孔过滤膜后,以气相色谱-串联质谱EI离子源,多反应监测模式(MRM)检测。结果表明:在0.005~1 mg/L范围内,3种供试农药的质量浓度与其相应的峰面积间呈良好的线性关系,决定系数(R2)均大于0.999。在0.025、0.050和0.25 mg/kg 3个添加水平下,3种农药的平均回收率为95%~101%,相对标准偏差(RSD)为0.7%~2.2%(n=6)。3种农药在玉米粉中的定量限(LOQ)分别为0.05、0.05和0.2μg/kg。该方法准确、灵敏、简单,适用于同时快速检测玉米粉中乙草胺、异丙甲草胺和三唑酮的残留量。