Determination of carbofuran residues and metabolites in plant material

An improved method for the analysis of carbofuran residues and its metabolites in plant material has been developed. Critical evaluation of previously published methods has enabled the elimination of unnecessary procedures, and practical difficulties have been overcome or minimised without loss of sensitivity. Separate extraction of bound and non-bound residues is followed by clean-up by coagulation, preparation of a derivative with 1-fluoro-2,4-dinitrobenzene, and gas-liquid chromatography using a thermionic nitrogen-selective detector system. The method can be used in general screening for carbamates as well as analysis for specific carbamate pesticide residues.     

Analytical methods for the detection and determination of residues of systemic fungicides

A review of the analytical methods for the detection and determination of residues of systemic fungicides in foodstuffs is presented.     

Comparative fate in soil of the enantiomers of triadimenol when applied individually to barley seed

The systemic fungicide triadimenol is a mixture of four enantiomers which have different biological activities. Dissipation and metabolism of the individual enantiomers in soil were investigated after seed treatment. Forty-nine days after 1R2S and 1S2S treatments, more of the radioactivity (87% for both) had dissipated from the seeds into the 0–10 cm soil layer than after the 1S2R (76%) and 1R2R (73%) treatments. After 1R2S treatment 56% of the radioactivity extracted from soil was accounted for as the parent isomer and 44% as its 1R2R epimer. After 1S2R treatment 76% of the radioactivity was in the parent form and 24% was converted to the 1S2S (17%) and 1R2R (7%) isomers.     

Daminozide residues in sweet cherries,and their determination by colorimetric and gas-liquid chromatographic methods

Daminozide residues in fruit from sweet cherry trees were determined over a period of 4 years as part of an investigation into the effects of growth regulators. Analysis was by the usual colorimetric method. Additionally, for the 2 final years, a gas-liquid chromatographic method was developed to determine the 1,1- dimethylhydrazine produced by hydrolysis of daminozide residues and to confirm the results from the first method.     

Instrumental methods for the analysis of herbicide residues*

Instrumental techniques for the residue analysis of herbicides in soil, water and plant material are reviewed. Various analytical methods, including gas chromatography using different detector systems, thin-layer chromatography, colorimetry, spectroscopy, as well as the use of labelled compounds for the evaluation of residue methods, are discussed.     

Bleaching of green plant material for liquid scintillation counting

A fast, economical, and reproducible method for the preparation of green plant samples for ¹⁴C quantitation by liquid scintillation spectrometry is presented. Uniform weights of green tissue (<0.4 g fresh wt) containing ¹⁴C are photooxidized (sunlight) in the presence of 1 ml water + 4 ml p-dioxane in scintillation vials. When a scintillation cocktail designed to hold water in suspension is added, a luminescence develops that decays within 24 hr. Correction for quenching by carotenoids is required.     

水稻田样品中噻呋酰胺残留检测方法研究

建立了噻呋酰胺在稻田土壤、稻田水、水稻秸秆、水稻绿色植株、谷壳和糙米中的残留检测方法。稻田水中的噻呋酰胺用LC-18固相萃取小柱分离、净化和富集;稻田土壤、水稻秸秆、谷壳和糙米样品采用V(丙酮):V(石油醚)=1:1超声提取,硅胶柱净化;绿色植株样品用石油醚超声提取,硅胶柱净化。提取净化后的所有样品均采用气相色谱-电子捕获检测器(GC-ECD)测定。结果表明,噻呋酰胺在0.005～10 mg/L范围内线性关系良好,相关系数(r)为0.999 1。其方法检出限分别为:稻田水中0.005 mg/L,土壤、水稻秸秆、绿色稻株、谷壳及糙米中均为0.004 mg/kg。 在水样中添加水平为0.05、0.5和1 mg/L及在土壤、秸秆、绿色稻株、谷壳和糙米中添加水平为0.04、0.4和4 mg/kg时,添加回收率均在86.6%～106.2%范围内,相对标准偏差(RSD)为1.3%～9.9%。     

Inhibition of ergosterol biosynthesis by triadimenol in Ustilago avenae

In Ustilago avenae sporidia, following the first doubling period of about 4 h, triadimenol (2 μg ml^?1) affected sporidial multiplication more severely than other growth processes; daughter cells failed to separate from the parent sporidia resulting in chains of interconnected cells. Triadimenol incubated with the fungus for 8 h interfered neither with respiration nor with protein and nucleic acid synthesis but after 6 h the toxicant had induced a higher content of free fatty acids. Triadimenol markedly altered, both quantitatively and qualitatively, the sterols in sporidia of U. avenae. Incorporation of [¹⁴C]acetate (in the form of sodium acetate) into lipid fractions for a period of 2 h revealed that the toxicant powerfully inhibited the synthesis of the 4-demethyl sterol fraction (predominantly ergosterol), whilst the 4,4-dimethyl sterol fraction rapidly accumulated. This was confirmed by g.1.c. analysis of the sterols after 6 and 8 h incubation which showed that the amount of ergosterol, the major sterol in untreated sporidia, was diminished while simultaneously 4,4-dimethyl, 4-methyl and 14-methyl sterols increased. The accumulation of 14-methyl sterols suggests that triadimenol acts as a potent inhibitor of one of the metabolic steps involved in the demethylation at the 14-position during ergosterol biosynthesis.     

High-pressure liquid chromatographic determination of sec-butylamine residues in potatoes

Fluorescamine, 4-phenylspiro[furan-2(3H), 1′(3′H)-isobenzofuran]-3,3′-dione, derivatives of primary aliphatic amines were separated by high-pressure liquid chromatography using a reverse-phase system with fluorescence detection. This technique was applied to the determination of residues of the fungicide sec-butylamine in potato tubers; the limit of detection was 0.36 pmol, equivalent to a residue of 0.1 mg kg^?1 in potato samples. A second amine, phenethylamine, was identified in extracts from artificially rotted potato flesh but this did not interfere with the analysis of sec-butylamine residues.     

三种基质中15种农药及其代谢物的不确定度评估

依据GB 23200.113—2018《食品安全国家标准植物源性食品中208种农药及其代谢物残留量的测定气相色谱-质谱联用法》中的QuEChERS方法,建立了一种气相色谱-串联质谱法(GC-MS/MS)测定茶叶、普通白菜和苹果3种基质中15种农药及其代谢物残留量的数学模型,通过分析测定过程的主要不确定度来源,对各个分量进行评估。结果表明：工作曲线拟合和回收率所引入的不确定度较大,其次为标准溶液配制和样品制备,而测量重复性和仪器引入的不确定度相对较小;不同基质对工作曲线拟合、回收率和测量重复性所引入的不确定度存在一定差异;不匹配基质校正曲线会对部分农药造成一定程度的基质增强或抑制效应。该方法适用于GC-MS/MS法测定植物源性食品中农药残留量的不确定度评估,可为农药残留测量结果的准确性提供科学可靠的依据。     

A colorimetric method for the determination of eight carbamate insecticide residues

A simple, quick and reliable method is described for the colorimetric estimation of residues of eight carbamate insecticides. The method is applicable to carbamates which on hydrolysis yield phenols with free para-positions suitable for coupling with a diazo reagent to yield coloured solutions. Optimum conditions for the development and measurement of the colour are described. Analytical data including graphs and some results from mud-bricks and cloth are presented to show the wide applicability of the method.     

A cultivation independent,PCR-based protocol for the direct identification of plant pathogens in infected plant material

A protocol involving PCR, shot-gun cloning and sequencing was developed as a pre-diagnostic screening tool working directly on disease symptoms. The method was used to show the presence of biotrophic and non-biotrophic eukaryotic plant pathogens in leaves and fruits.     

Method for the determination of butachlor residues in water,soil and rice

A method is described for the analysis of water, soil and crops for residues of the herbicide butachlor. Residues were extracted with acetone + light petroleum distillate. The extracts were concentrated and purified on a chromatographic column containing aluminum oxide, silver–aluminum oxide and Florisil. Finally, they were quantitated by gas chromatography using an electron-capture detector. The detection limits of various samples were between 0.001 and 0.015 mg kg^?1. The average recoveries ranged from 79.4 to 104.6%.     

The determination and study of residues of flamprop-isopropyl in soil

Residue analytical studies are reported on soils from trial sites in the UK and France following applications of flamprop-isopropyl ( I ) to growing crops. The analytical procedure developed allowed the determination of I and its hydrolysis product N-benzoyl-N-(3-chloro-4-fluorophenyl)-DL -alanine ( II ). The residues in the soil often increased during some weeks after application due to transfer of I from the crop to the soil, so that measurement of the initial half-life of I in soil was unusually difficult. However, it was probably within the range 4–20 weeks. Both I and II were detected in field soils, but neither compound was persistent in soil and normally little or no carry-over of residues occurred from one season to the next, although greater persistence was found in one Kentish trial.     

The determination of residues of 2,4-D in post-emergence-treated triticale

A gas chromatographic method, using electrolytic conductivity detection, is presented for the determination of 2,4-0 as its methyl ester in triticale (X Triticosecale Wittmack). The method was used to monitor the dissipation of 2,4-0 residues in triticale over a growing season at two sites following post-emergence application of the dimethylamine salt of 2,4-D at 0.56 kkg ha^?1. Initial residues, in the order of30 mg kg^?1. on the day afer application (3- to 4-leaf stage of the crop), decreased to non-detectable levels in the mature straw and seed. Recoveries of 2,4-D were greater than 90% fiom green tissue fortified at 0.1 mg k^?1., and in the order of 75% from seed fortified at 0.05 mg kg^?1.     

A highly mutable major gene for triadimenol resistance in Nectria haematococca var. cucurbitae

Mutants ofNectria haematococca var.cucurbitae with high resistance to triadimenol could be isolated at high frequency. Resistance of 30 such mutants studied, was due to a mutation at thetri-1 locus, that maps in linkage group I, 10 cross-over units from the mating type locus. Thetri-1 mutation has no obvious effects on growth and sporulation on media without fungicide and on virulence for squash seedlings and mature fruit. In addition, a resistant mutant killed all of artificially inoculated seedlings in the presence of triadimenol at a concentration which gave 100% protection against the original wild type strain. Thetri-1 mutants were crossresistant at various levels to triadimefon, bitertanol, and propiconazol, but not to non-triazole SBIs. Their sensitivity to three imidazole derivatives was even higher than that of the wild type strains. This is believed to be the first report of a major gene for resistance to an SBI fungicide.Isolatie vanNectria haematococca var.cucurbitae mutanten met een hoog niveau van resistentie tegen triadimenol bleek zeer gemakkelijk. Uit genetische analyse van 30 van deze mutanten bleek dat in alle een mutatie voorkwam in de tri-1 locus die kon worden gelokaliseerd op koppelingsgroep I, 10 overkruisingseenheden verwijderd van de mating-type locus. Detri-1 mutatie had geen waarneembare effecten op groei en sporulering van de schimmel op fungicide-vrij medium en op pathogeniteit ten aanzien van zaailingen en rijpe vruchten van pompoen.Triadimenol-behandeling van zaailingen bleek aantasting door de resistente mutant niet te kunnen voorkomen, terwijl behandeling wel effectief bleek tegen de ouderstam.     

A small-scale method for the determination of pyrethroid insecticide residues in crops and soils

A small-scale method for the determination of pyrethroid insecticide residues in crops and soils is described. Compared with the conventional methods, the overall analysis time is reduced by approximately 60% and solvent usage is reduced by approximately 80% using this approach. Results obtained on a range of crops using the small-scale and conventional methods were in good agreement, and a repeatability study showed that the small-scale approach is unbiased and gives good precision. To date, linseed, tobacco, cotton foliage, cotton seed, wheat grain, sorghum, savoy, cauliflower, cabbage, cucumber, apple, peach, blackcurrant, gooseberry, raspberry and soil samples have been analysed using the method. Good recoveries were obtained with all these matrices.     

三唑醇对映体的反相高效液相色谱拆分热力学研究

在高效液相色谱反相条件下,利用涂敷型纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC-CSP)对三唑醇4个对映异构体进行了直接手性拆分研究。考察了不同流动相组成和柱温对三唑醇对映体的色谱保留及分离的影响。同时,利用热力学方法对三唑醇对映体与固定相之间的色谱保留和分离的热力学机理进行了探讨。结果表明:在以甲醇-水(70∶ 30,体积比)为流动相、流速0.8 mL/min、柱温15 ℃,或在以乙腈-水(30∶ 70,体积比)为流动相、流速1.0 mL/min、柱温45 ℃的条件下,三唑醇对映体可以得到较好分离。     

Bound xenobiotic residues in food commodities of plant and animal origin

The following are extended summaries of Technical Reports which are produced at intervals by the International Union of Pure and Applied Chemistry (IUPAC). They are entirely the responsibility of IUPAC/the authors and do not necessarily reflect the views of the Editorial Board of Pest Management Science. Copyright © 2002 Society of Chemical Industry