Solid-phase extraction of acidic herbicides

A discussion of solid-phase extraction method development for acidic herbicides is presented that reviews sample matrix modification, extraction sorbent selection, derivatization procedures for gas chromatographic analysis, and clean-up procedures for high-performance liquid chromatographic analysis. Acidic herbicides are families of compounds that include derivatives of phenol (dinoseb, dinoterb and pentachlorophenol), benzoic acid (acifluorfen, chloramben, dicamba, 3,5-dichlorobenzoic acid and dacthal--a dibenzoic acid derivative), acetic acid [2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)], propanoic acid [dichlorprop, fluazifop, haloxyfop, 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and silvex], butanoic acid [4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB) and 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB)], and other miscellaneous acids such as pyridinecarboxylic acid (picloram) and thiadiazine dioxide (bentazon).     

A Method for Determination of Low Levels of Exposure to 2,4-D and 2,4,5-T

A method has been developed for the determination of trace quantities of 2,4-dichloro-phenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 2,4-dichlorophenol (2,4-DCP), and 2,4,5-trichlorophenol (2,4,5-TCP) in human and rat urine. The method involves acid hydrolysis of the phenolic conjugates, extraction of the free phenols and acids, ethylation with diazoethane, silica-gel column chromatography clean-up of the derivatized urine extract, and gas chromatographic determination using the electron-capture detector. The average recoveries of 2,4-D, 2,4,5-T, 2,4-DCP, and 2,4,5-TCP from rat urine spiked with known amounts of the herbicides and their phenols were 94%, 98%, 92%, and 90%, respectively. The limits of detection for 2,4-D, 2,4,5-T, DCP, and TCP in rat urine were: 0.05, 0.01, 0.10, and 0.01 ppm, respectively. The method was used to analyze urine of rats given various levels of 2,4-D and 2,4,5-T by gavage. Results showed that levels of exposure of 3.75 mcg/kg for 2,4-D and 5.0 mcg/kg for 2,4,5-T in rats can be detected in urine within 24 hr from exposure. Urine samples from occupationally exposed people were analyzed and found to contain 0.2 to 1.0 ppm 2,4-D and 0.05 to 3.6 ppm 2,4,5-T.     

The characterization of prepared organomontmorillonite (DEDMAM) and sorption of phenoxyalkanoic acid herbicides from aqueous solution

The montmorillonite has been subjected to modification through ion-exchange reaction by N,N'-didodecyl-N,N'-tetramethylethanediammoniumdiiodide (DEDMAI). The modified sample was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The basal spacing of modified montmorillonite was determined as 28.72 A. The IR spectra of organomontmorillonite showed changes in C-H vibrations. The characterization of N,N'-didodecyl-N,N'-tetramethylethanediammonium montmorillonite (DEDMAM) and the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4-dichlorophenoxybutyric acid (2,4-DB), 4-chloro-2-methylphenoxyacetic acid (MCPA), and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on organomontmorillonite was studied as a function of the solution concentration. The adsorption energy (E) and adsorption capacity (qm) for phenoxyalkanoic acid herbicides adsorbing on organomontmorillonite (DEDMAM) were estimated using the Dubinin-Radushkevic (D-R) equation. These isotherms were modeled according to Freundlich and Dubinin-Radushkevic adsorption isotherms. The sorption of the herbicides on DEDMAM increased in order of MCPA<2,4-D<2,4-DB<2,4,5-T.     

Microwave and ultrasonic extraction of chlorophenoxy acids from soil and their determination by fluorescence polarization immunoassay

Procedures were developed for the ultrasonic and microwave extraction of pesticides, 2,4-dichlorophenoxyacetic (2,4-D) and 2,4,5-trichlophenoxyacetic (2,4,5-T) acids from soils for the subsequent determination by fluorescence polarization immunoassay (FPIA). The effect of the matrix composition of soils on the FPIA results was studied, and the optimum extractants and extraction conditions were selected. It was found that 40% ethanol is optimum for both extraction and FPIA determination, because it does not cause antibody denaturation. The recovery of pesticides in soil was 80–132% for 2,4-D and 101–138% for 2,4,5-T. Microwave extraction is more efficient than ultrasonic extraction for the determination of 2,4-D and 2,4,5-T in soil. The detection limit in soil and the analytical range are 2 and 4–200 μg/g, respectively, for 2,4-D and 20 and 80–5000 μg/g, respectively, for 2,4,5-T. Results of the determination of 2,4-D in soil by FPIA are in good agreement with the results of the determination by high-performance liquid chromatography. The procedures can be used for the rapid determination of chlorophenoxy acids in soils.     

Optimizing Separation Conditions for Chlorophenoxycarboxylic Acid Herbicides in Natural and Potable Water Using Capillary Zone Electrophoresis

Chlorophenoxycarboxylic acid herbicides were separated and determined by capillary electrophoresis. An analysis of a six-component mixture containing 2,4-dichlorophenoxybutyric (2,4-DB), 2,4-dichlorophenoxypropionic (2,4-DP), 2,4,5-trichlorophenoxyacetic (2,4,5-T), 2,4-dichlorophenoxyacetic (2,4-D), and phenoxyacetic (PA) acids and 2,4-dichlorophenol (2,4-DCP), the product of their degradation in aqueous media, took no longer than 15 min. Solid-phase extraction on Diapak C-16 cartridges was used for sample preparation. The detection limits for herbicides in water samples with account for preconcentration (K = 250) were found to be 0.0005 mg/L for 2,4-DB, 2,4-DP, 2,4,5-T, and 2,4-D and 0.001 mg/L for PA. It was shown that humic acids (< 50 mg/L) do not interfere with the determination of chlorophenoxycarboxylic acids.     

气相色谱-质谱法分析卷烟烟丝和“九曲红梅”红茶样品在加热不燃烧条件下释放出的挥发物及用掺入红茶的烟丝制卷烟的初步探讨

将"九曲红梅"红茶(以下简称红茶)与卷烟烟丝样品分别经过粉碎并通过0.177mm网筛,制成分析用样品。称取0.2mg样品,在裂解炉中,温度为200℃的条件下,在氦气氛围中,样品挥发性成分瞬间气化,由载气带入气相色谱-质谱仪器系统,经分离和测定,得到了两种样品在此条件下所释放出成分。烟丝样品在此加热不燃烧条件下,释放的物质主要有人为添加的发烟剂丙三醇(59.34%),以及其本身的组分烟碱(20.34%)、3-丁炔-1-醇(4.32%)、5-羟甲基糠醛(3.23%)和2,3-二氢-3,5-二羟基-6-甲基-4(H)-吡喃-4-酮(2.12%)等。红茶样品中释放出的主要成分有咖啡因(86.23%)以及16种低含量特征组分。将此红茶样品按质量百分比为5%,10%,30%的比例加入卷烟烟丝中,并测定其在加热不燃烧的条件下释放物质量的变化,并结合感官评价。结果发现:混入不同比例红茶的烟丝,加热后释放出的气体中咖啡因的含量按茶叶的配比量的增加依次为0.71%,1.96%,7.23%;感官评价表明红茶加入卷烟烟丝中,提升了卷烟烟气的优雅感,强化了卷烟的果香、甜香、花香等香韵,提升了香气量和香气丰富性,细腻柔和烟气,改善余味,增强回甜感。当茶叶的加入量为10%时,在余味和口感上有较好的效果,具有全面提升感官品质的功效,整体抽吸舒适性和协调性较好,香气的质和量适中。     

QuEChERS/HPLC/DAD法同时检测果蔬中多种植物激素残留

采用高效液相色谱法,建立了同时分析玉米素(Z)、赤霉酸(GA)、多效唑(PBZ)、4-氟苯氧乙酸(4-FPA)、4-氯苯氧乙酸(4-CPA)、吲哚-3-乙酸(IAA)、吲哚-3-丁酸(IBA)、6-苄氨基嘌呤(6-BA)、脱落酸(ABA)、萘乙酸(NAA)、氯吡脲(CPPU)、2,4-二氯苯氧乙酸(2,4-D)及2,4,5-三氯苯氧乙酸(2,4,5-T)13种植物激素含量的方法。采用含0.5%甲酸的80%乙腈进行提取,分散固相萃取吸附剂(C18和硅藻土)进行净化,选取Waters XBridge C_(18)色谱柱,以乙腈-水为流动相进行梯度洗脱,二极管阵列检测器200~400nm检测,外标法定量。结果表明,13种植物激素在50 min内可实现基线分离,在线性范围内的相关系数(r)为0.992 1~0.999 3;加标回收率为68.4%~95.1%;相对标准偏差(RSD)均小于5%;方法的检出限为0.005~0.020 mg/kg;定量下限为0.01~0.09 mg/kg。该方法前处理操作快速、简便,具有良好的灵敏度、精密度和回收率,适用于果蔬的质量监控。     

气相色谱–质谱法测定棉花中苯氧羧酸类除草剂

采用气相色谱–质谱联用法检测棉花中3种苯氧羧酸类除草剂[2,4-D,2,4,5-T,2-甲-4-氯丁酸(MCPB)]的残留量。样品用甲酸酸化的丙酮提取,硫酸催化甲酯化反应,用气相色谱–质谱联用仪测定。采用HPLC法与GC–MS法对提取与衍生化步骤进行优化。2,4-D,2,4,5-T,MCPB 3种化合物在0.075~7.5 mg/kg范围内线性均良好,检出限分别为0.5,0.5,0.8μg/kg,测定结果的相对标准偏差分别为4.1%,4.3%,4.0%(n=5),方法回收率分别为93.6%,95.5%,93.9%。该方法各项指标均可满足检测要求。     

Octadecyl silica membrane disks modified with a new Schiff's base for the preconcentration of lead and copper before their determination in water samples

A simple and fast method for the extraction and determination of ppt level of Pb2+ and Cu2+ ions using octadecyl-bonded silica membrane disks modified by a new tetradentates Schiffs base [Bis(2,4-dimethoxy benzaldehyde) ethylen diimine](TDSB) and inductively coupled plasma atomic emission spectrometry is described. Extraction efficiency, and influence of flow rate, pH, type and the least amount of acid for stripping of Cu2+ and Pb2+ from the modified disks and break through volume were evaluated. The maximum capacity of the membrane disks modified by 5 mg of TDSB used was found to be 347 +/- 7 and 470 +/- 6 microg of copper and lead, respectively. The concentration factor is 500 (for 2500 mL water sample and flow rate of 20 mL min(-1)) and detection limit of the proposed method is 12.5 and 150.5 pg/ml for Cu2+ and Pb2+, respectively. The method was applied to the determination of Cu2+ and Pb2+ ions from various water, wastewater, black tea, and hot pepper samples.     

A new disubstituted acetylacetone from the leaves of Bidens pilosa Linn

Phytochemical investigation of the leaves of Bidens pilosa lead to the isolation and characterization of a new disubstituted acetylacetone (1) named as 3-Propyl-3-(2,4,5-trimethoxy)benzyloxy-pentan-2,4-dione.     

Development and Comparative Study of Different Immunoenzyme Techniques for Pesticides Detection

Abstract

Different ELISA techniques have been developed for the detemination of four widely used pesticides: 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), simazine and atrazine. Dependences between the assay scheme and the limiting detectable concentration of the pesticide were studied. The cases of preferential applying of the scheme with immobilized antibodies or one with immobilized pesticide-protein conjugate have been revealed. The following approaches resulting in lowering of ELISA sensitivity were proposed: preliminary incubation of the tested sample with antibodies, immobilization of antibodies via staphylococcal protein A, usage of monovalent fragments of antibodies instead of native ones and chemical modification of the pesticide molecules in the sample. Optimal combinations of these approaches permitted to lower the detection limit of the assays in about 5–30 times. The achieved sensitivities were 3 ng/mL for 2,4-D, 5 ng/mL for 2,4,5-T, 0.05 ng/mL for simazine, and 0.1 ng/mL for atrazine, being acceptable for purposes of ecological monitoring.     

Immuno-arrays for multianalyte analysis of chlorotriazines

In this paper, a novel strategy for multicomponent analysis of two classes of pesticides such as triazines (atrazine and simazine) and phenoxyalkanoic acids (2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 4-chlorophenoxyacetic acid (CPOAc), phenoxyacetic acid (POAc)) employing immuno-arrays is demonstrated. The approach is based on cross-reactive arrays of specific antibody pairs coupled to chemometric pattern recognition. The monoclonal antibody pairs employed in this work (atrazine-simazine and 2,4-D) are specific towards a set of analytes and preclude a particular set of others present in the sample matrix. Antibody pairs of atrazine, simazine, and 2,4-D are used to discriminate and quantify analyte of interest. Atrazine was quantified in presence of trace concentration of simazine and that of 2,4-D. The combinatorial cross-reactivity of antibody pairs towards simazine, atrazine and 2,4-D is used to distinguish among different classes of analytes and their influence on the signal suppression in immuno-techniques. These sensors exclude recognition by carbamates such as carbaryl and carbofuran.     

Antimicrobial Depsides Produced by Cladosporium uredinicola,an Endophytic Fungus Isolated from Psidium guajava Fruits

Four depsides, all of them new as natural products, were isolated from Cladosporium uredinicola solid‐media culture and identified as 3‐hydroxy‐2,5‐dimethylphenyl 2,4‐dihydroxy‐3,6‐dimethylbenzoate ( 1 ), 3‐hydroxy‐2,4,5‐trimethylphenyl 2,4‐dihydroxy‐3,6‐dimethylbenzoate ( 2 ), 3‐hydroxy‐2,5‐dimethylphenyl 3‐[(2,4‐dihydroxy‐3,6‐dimethylbenzoyl)oxy]‐6‐hydroxy‐2,4‐dimethylbenzoate ( 3 ), and 3‐hydroxy‐2,4,5‐trimethylphenyl 3‐[(2,4‐dihydroxy‐3,6‐dimethylbenzoyl)oxy]‐6‐hydroxy‐2,4‐dimethylbenzoate ( 4 ). The endophytic fungus was isolated from Psidium guajava fruits and cultivated over sterilized rice. The compounds 1 – 4 were purified by classical chromatographic procedures, and the chemical structures were identified by spectroscopic studies, mainly 1D‐ and 2D‐NMR and LC/ESI‐MS/MS. Three of the isolated depsides exhibited moderate bacteriostatic and/or bactericide effects on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtillis.     

固相萃取-超高效液相色谱-串联质谱法测定人尿中苯氧乙酸除草剂和有机磷、拟除虫菊酯农药代谢物北大核心CSCD

基于96孔固相萃取-超高效液相色谱-串联质谱法,建立了人尿中2种苯氧乙酸除草剂、2种有机磷农药代谢物和4种拟除虫菊酯农药代谢物的测定方法。通过对液相色谱条件、质谱条件和样品前处理过程的系统优化,实现了在16 min内对8种目标分析物的分析测定。具体方法:1 mL尿液经β-葡萄糖醛酸酶酶解过夜,Oasis HLB 96孔固相萃取进行目标分析物的提取净化,甲醇洗脱;以0.1%(体积分数)乙酸乙腈和0.1%(体积分数)乙酸水作为流动相,Acquity BEH C_(18)作为分析柱进行色谱分离;负离子电喷雾(ESI-)多反应监测(MRM)模式下检测目标化合物,同位素内标法定量。2,4-二氯苯氧乙酸(2,4-D)、2,4,5-三氯苯氧乙酸(2,4,5-T)2种苯氧乙酸除草剂和3-苯氧基苯甲酸(3-PBA)、4-氟-3-苯氧基苯甲酸(4F-3PBA)、反式二氯乙烯基二甲基环丙烷羧酸(trans-DCCA)3种拟除虫菊酯农药代谢物在0.1~100μg/L内、对硝基苯酚(PNP)、3,5,6-三氯-2-吡啶酚(TCPY)2种有机磷农药代谢物、顺式二氯乙烯基二甲基环丙烷羧酸(cis-DCCA)1种拟除虫菊酯代谢物在0.2~100μg/L内线性关系良好,相关系数均大于0.9993;方法检出限为0.02~0.07μg/L,方法定量限为0.08~0.2μg/L;低、中、高3个水平下的加标回收率为91.1%~110.5%,日内精密度为2.9%~7.8%,日间精密度为6.2%~10%。应用该方法测定了214份尿液样本。结果显示除2,4,5-T外,其余7种目标分析物均有检出。TCPY、PNP、3-PBA、4F-3PBA、trans-DCCA、cis-DCCA、2,4-D的检出率为2.8%~99.1%。检出浓度(中位值)由高到低分别是2.0μg/L(TCPY)、1.8μg/L(PNP)、0.99μg/L(trans-DCCA)、0.81μg/L(3-PBA)、0.44μg/L(cis-DCCA)、0.35μg/L(2,4-D)和未检出(4F-3PBA)。该方法操作简便,定量准确,灵敏度高,每批次可完成96个样品测定,适用于人尿中多种农药及农药代谢物的批量分析测定。     

Microwave-assisted water extraction of acid herbicides from soils coupled to continuous filtration, pre-concentration, chromatographic separation and UV detection

A microwave-assisted extraction procedure using water as extractant has been performed for the extraction of acid herbicides (namely, bentazone, 2,4-D, trichlopyr, 2,4,5-T and 2,4,5-Tp) from different types of soil. Two experimental designs were used for the optimization of the leaching step. The selection of water as extractant provided a clean approach by avoiding the use of organic solvents. The use of water also enhanced the extraction efficiency due to the high interaction of the microwave irradiation with polar solvents. The time required for total removal of the target compounds was 35 min. The recoveries yield were from 87.64 to 106.14% with a repeatability (expressed as relative standard deviation) ranging between 1.34 and 9.24%. A within-laboratory reproducibility, also expressed as relative standard deviation, varied from 3.97 to 10.41%. A flow-injection manifold allowed automation of the whole process by hyphenating the steps subsequent to extraction (namely, filtration, preconcentration, chromatographic separation and UV detection) for the determination of the analytes.     

Construction,Expression, and Characterization of a Single-Chain Variable Fragment Antibody Against 2,4-Dichlorophenoxyacetic Acid in the Hemolymph of Silkworm Larvae

A single-chain variable fragment antibody against herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D-scFv) has been successfully expressed in the hemolymph of silkworm larvae using a rapid Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid DNA system. Variable heavy- and light-chain domains were cloned directly from the cDNA of the hybridoma cell line 2C4 and assembled together with flexible peptide linker (Gly₄Ser)₃ between two domains. The yield of functional 2,4-D-scFv after purification was 640 μg per 30 ml of hemolymph, which is equivalent to 21.3 mg per liter of hemolymph. The characterization of 2,4-D-scFv using an indirect competitive enzyme-linked immunosorbent assay (icELISA) revealed that it has wide cross-reactivities against 2,4,5-trichlorophenoxyacetic acid (65.5%), 2,4-dichlorophenol (47.9%), and 2,4-dichlorobenzoic acid (26.0%), making it possible to apply 2,4-D-scFv to icELISA for detecting/determining 2,4-D and its metabolites. Judging from its cost and time requirements and its ease of handling, this BmNPV bacmid DNA expression system is more useful for expressing functional scFv than bacterial systems, which frequently require costly and time-consuming refolding.     

Development of HPLC-MS/MS method for the simultaneous determination of environmental phenols in human urine

We present a sensitive method for simultaneous determination of bisphenol A (BPA), benzophenone-3 (BP-3), 4-tert-octylphenol (t-OP), ortho-phenylphenol (OPP), four parabens (methyl, ethyl, propyl, butyl parabens) and five chlorophenols (2,4-dichlorophenol (2,4-DCP), 2,5-dichlorophenol (2,5-DCP), 2,4,5-trichlorophenol (2,4,5-triclorophenol), 2,4,6-trichlorophenol (2,4,6-TCP), and triclosan (TCS)), in human urine by high-pressure liquid chromatography (HPLC) mass spectrometry (MS). Samples were processed using enzymatic deconjugation of glucuronides followed by solid phase extraction (SPE) on a C18 cartridge and the eluate was concentrated. Analytes were separated by reversed-phase HPLC and then detected by atmospheric pressure chemical ionisation (APCI) MS and quantified by isotope dilution method. We describe details for optimisation of each step of the procedure. The sample treatment steps are straightforward and not labour-intensive and, therefore, permit a high sample throughput with excellent prospects for automation. This method shows low inter-day variation, and detection limits for most of the compounds are below 1 ng/mL in 1 mL of urine. The method accuracy was also verified by the analysis of proficiency testing urine samples.     

Analysis of some chlorophenoxy acids and carbamate herbicides in water and soil as amide derivatives using gas chromatography-mass spectrometry

A newly developed method for determining three phenoxy acids and one carbamate herbicide in water and soil samples using gas chromatography with mass spectrometric detection is developed. Phenoxy acids are derivatized through a condensation reaction with a suitable aromatic amine. 1,1-Carbonyldiimidazole is used as a condensation reagent. Derivatization conditions are optimized with respect to the amount of analyte, amine, solvent, and derivatization reagent. The optimum derivatization yield is accomplished in acetonitrile. 4-Methoxy aniline is used as a derivatizing agent. Obtained derivatives are stable indefinitely. Enhancement in sensitivity is achieved by using the single-ion monitoring mass spectrometric mode. The effectiveness of the developed method is tested by determining investigated compounds in water and soil samples. Analytes are concentrated from water samples using liquid-phase extraction and solid-phase extraction. Soil samples are extracted using methanol. Detection limits of 1.00, 50.00, 100.00, and 1.00 ng/mL are obtained for 2-(1-methylethoxy)phenyl methylcarbamate (Baygon), 2-(3-chlorophenoxy)-propionic acid (Cloprop), 2,4,5-trichlorophenoxyacetic acid, and 4-(2,4-dichlorophenoxy)butyric acid, respectively. LPE for spiked water samples yields recoveries in the range of 60.6-95.7%, with relative standard deviation (RSD) values of 1.07-7.85% using single component calibration curves. Recoveries of 44.8-275.5%, with RSD values ranging from 1.43% to 8.61% were obtained using a mixed component calibration curves. SPE from water samples and soil samples showed low recoveries. The reason is attributed to the weak sorption capabilities of soil and Al(2)O(3).     

Multivariate Optimization Approach for Chiral Resolution of Chlorophenoxy Acid Herbicides Using Teicoplanin as Chiral Selector in Capillary LC

In this paper, the selectivity and resolution of enantiomeric separation by capillary liquid chromatography (cLC) of racemates of phenoxy acid herbicides are modelled. The compounds studied were 2-(±)-(2,4,5-trichlorophenoxy)propanoic acid (2,4,5-TP), 2-(±)-(2,4-dichlorophenoxy)propanoic acid (2,4-DP), 2-(±)-(4-chloro-2-methyl)phenoxypropanoic acid (MCPP) and 2-(±)-[4-(2,4-dichlorophenoxy)phenoxy]propanoic acid] (diclofop acid), using a capillary column packed with silica particles modified with teicoplanin as chiral selector. Several mixtures of methanol (MeOH), water and triethylamine acetate (TEAA) buffer at different pHs have been tested as mobile phases, and experimental parameters such as resolution (Rs), retention factor (k) and enantioselectivity factor (α) have been measured in all tested conditions. The chemometric methods used to explore and to model the data were principal component analysis (PCA), stepwise multiple linear regression (stepwise-MLR) and response surface analysis (RSA). The results show that it is possible to quantitatively predict the quality of enantiomeric separations of related compounds in a given chromatographic system.     

Synthesis of Highly Substituted Oxazoles through Iodine(III)-Mediated Reactions of Ketones with Nitriles

In the presence of trifluoromethanesulfonic acid (TfOH) or bis(trifluoromethane-sulfonyl)imide (Tf₂NH), iodosobenzene (PhI=O) efficiently promoted the reactions of dicarbonyl compounds as well as monocarbonyl compounds with nitriles to give 2,4-disubstituted and 2,4,5-trisubstituted oxazole in a single step under the mild conditions.