A rapid high-pressure liquid chromatographic method for the determination of carbaryl residues in wheat grain

Carbaryl residues in wheat grain have been determined in methanol extracts using normal-phase high-pressure liquid chromatography (h. p. l. c.) with ultraviolet detection. A single-injection, clean-up and analysis technique was used to allow more rapid analysis of samples after extraction. A detection limit of 0.1 mg kg^?1 in a 50 g sample of wheat was achieved. Recoveries of 86% at the 1 mg kg^?1 level and 90-99% at the 5 mg kg^?1 level were obtained for fortified grain samples. Methanol was found to be a superior extractant for carbaryl from wheat when compared with hexane, acetone and dichloromethane. Twelve samples containing aged carbaryl residues were analysed by the h. p. l. c. technique and by a colorimetric procedure which allowed statistical analysis of errors. For the h. p. l. c. method (excluding sampling error), a relative standard deviation of 4.4% was obtained.     

Determination of residues of 1-(2-cyano-2- methoxyiminoacetyl)-3-ethylurea (DPX-3217) by gas-liquid chromatography

Residues of the fungicide 1-(2-cyano-2-methoxyiminoacetyl)-3-ethylurea (DPX-3217) in grapes, potatoes, tomatoes and wine were determined by initial extraction with ethyl acetate, clean-up by liquid-liquid partitioning and adsorption chromatography, and final determination by gas-liquid chromatography with a nitrogen-selective detector. The sensitivity of the method was 0.04 mg kg^?1 based on 50-g samples. Recoveries of the compound added to untreated substrates averaged approximately 92% in the range of 0.04-5.0 mg kg^?1.     

Determination of sugarbeet herbicides in soil samples by hplc

Determination of sugarbeet herbicides such as chloridazon, metamitron and phenmedipham in soil samples is described. After extraction with acetone, pesticides were determined by HPLC on an RP-18 column using methanol/water as mobile phase. Average recoveries were 82% for chloridazon, 93% for metamitron and 77% for phenmedipham. Quantification limits were 3·5 μg kg^?1 for chloridazon, 6·3 μg kg^?1 for metamitron and 3·6 μg kg^?1 for phenmedipham.     

Simultaneous determination of clofentezine,fenoxycarb and hexythiazox by HPLC on apples,pears and their pulps

The simultaneous HPLC determination of clofentezine, fenoxycarb and hexythiazox in apples, pears and their pulps is described. The method is based on a clean-up procedure carried out on a Seppak C18 cartridge followed by HPLC analysis on an RP-18 column using acetonitrile + water as mobile phase. Average recoveries were 85.0% for clofentezine, 84.8% for fenoxycarb and 75.6% for hexythiazox on apple matrix; recoveries from pear matrix were in the same range. UV detection limits at 240 nm were 0.07 mg kg^?1 for clofentezine, 0.064 mg kg^?1 for fenoxycarb and 0.08 mg kg^?1 for hexythiazox.     

The estimation of residue levels of promacyl and its metabolites in beef tissue and fat by high-performance liquid chromatography with electrochemical detection

A method is described for the estimation of residues of the carbamate insecticide promacyl [5-methyl-m-cumenyl butyryl(methyl)carbamate] and its metabolites that are hydrolysable to isothymol (m-cymen-5-ol), using high-performance liquid chromatography with electrochemical detection to determine the isothymol. Clean-up of samples relied on the steam volatility of phenols. Recoveries at the 0.1 mg kg^?1 level varied from 72–88% for fat tissue and 81–91% for liver. The limits of detection were found to be 0.01 mg kg^?1 for and 0.02 mg kg^?1 for liver. A comparative study of the chromatography of sample extracts using both ultraviolet detection and electrochemical detection showed a substantial decrease in the level of interfering co-eluates in the latter method. A field trial, involving a single spray application of the formulated acaricide on milking cattle, revealed residues in the butter fat comparable with those found in a previous investigation.     

Acaricides and their residues in Spanish commercial beeswax

BACKGROUND: The purpose of this work was to determine residues of acaricides in recycled Spanish beeswax. RESULTS: Chlorfenvinphos, fluvalinate, amitraz, bromopropylate, acrinathrin, flumethrin, coumaphos, chlorpyrifos, chlordimeform, endosulfan and malathion residues were determined by GC‐µECD/NPD/MS detection. Owing to the extreme instability of amitraz, this analyte was transformed into the stable end‐metabolite 2,4‐dimethylaniline, later derivatised with heptafluorobutyric anhydride and determined by GC‐µECD/MS. Recoveries from spiked samples ranged from 86 to 108%, while quantification limits varied from 0.10 to 0.30 mg kg^?1 using GC‐µECD/NPD, and from 12 to 85 µg kg^?1 by GC‐MSD. Of a total of 197 samples analysed, only eight samples (4%) were free of residues of chlorfenvinphos (0.019–10.6 mg kg^?1), fluvalinate was present in 93.6% of samples analysed (0.027 –88.7 mg kg^?1), while coumaphos was confirmed in only five of the 134 samples analysed at concentrations of less than 195 µg kg^?1. The remaining acaricides were identified with different levels of incidence at concentrations from 12 to 231 µg kg^?1. CONCLUSIONS: Residues of acaricides were found in an extensive number of beeswax samples. The contamination with chlorfenvinphos and tau‐fluvalinate was very relevant, particularly as chlorfenvinphos is not legally authorised for use in beekeeping. The possible impacts of the main acaricides detected on larval and adult honey bees are discussed. Copyright © 2010 Society of Chemical Industry     

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%.     

Appearance of a biotype of the weed, Hordeum glaucum Steud., resistant to the herbicide paraquat

A biotype of the grass weed Hordeum glaucum Steud, infesting a site at Willaura, Victoria, Australia has resistance to paraquat. Application of the recommended rate of paraquat does not cause death of the resistant biotype at any stage of growth. The LD₅₀ for the resistant biotype is 6.4 kg active ingredient ha^?1 which is 250 times greater than for the normal susceptible biotype (25 g active ingredient ha^?1). Growth of the resistant biotype is checked by paraquat with a clear dosage response evident. The paraquat resistant biotype is also resistant to diquat but is normally affected by herbicides with different modes of action. In addition to continued foliage growth of the resistant plants after paraquat application, seeds of these plants can germinate and seedlings elongate in the dark whereas seeds of susceptible plants germinate but there is no further growth. This suggests that studies of the mechanism(s) conferring resistance will have to consider both the effect of paraquat on the chloroplast and a non-photosynthetic effect on cell growth. Un biotype de la mauvaise herbe Hordeum glaucum Steud, résistant à l'herbicide paraquat Un biotype de la graminée Hordeum glaucum Steud. à Willaura, Victoria, Australie, s'est montré résistant au paraquat. L'application de la dose préconisée de paraquat ne provoque pas la mort de ce biotype, quel qu'en soit le stade végétal. La LD₅₀ pour le biotype résistant est 6,4 kg matière active ha^?1, c'est-à-dire 250 fois plus grande que pour le biotype normal sensible (25 g matière active ha^?1). Le paraquat provoque chez le biotype résistant une inhibition de croissance qui se rapporte à la dose. Le biotype résistant au paraquat l'est également au diquat mais réagit normalement envers les herbicides à mode d'action différente. Non seulement la croissance foliaire continue normalement après une application de paraquat chez les plantes résistantes, mais les graines sont capables de germer et les jeunes plants de s'allonger à l'obscurité, tandis que les graines de plantes sensibles germent à l'obscurité mais ne croissent pas. II semble donc que les études des mécanismes qui produisent la résistance devront examiner l'influence du paraquat sur le chloroplaste ainsi qu'un effet nonphotosynthétique sur la croissance cellulaire. Ueber das Auftreten eines gegen Paraquat resistenten Biotyps von Hordeum glaucum Steud. Bei Willaura, Victoria (Australien) tritt ein gegen Paraquat resistenter Biotyp von Hordeum glaucum Steud. auf. Die Application der normalerweise empfohlenen Dosierung Paraquat tötet den resistenten Biotyp in keinem Wachstumsstadium ab. Die Ld₅₀ für den resistenten Typ beträgt 6,4 kg ai ha^?1; dies ist 250 mal mehr als beim normal sensiblen Typ (25 g ai ha^?1). Das Wachstum des resistenten Biotyps wird durch steigende Dosen von Paraquat beeinträchtigt. Der gegen Paraquat resistente Typ ist auch gegen Diquat unempfindlich, weist aber gegenüber Herbiziden mil anderen Wirkungsmechanismen die normale Empfindlichkeit auf. Resistente Pflanzen zeigen nach Paraquatbehandlung ein weitergehendes Blattwachstum. Ihre Samen keimen und die Sämlinge entwickeln sich im Dunkeln weiter, während die Samen sensibler Pflanzen zwar keimen, sich aber nicht weiterentwickeln. Diese Beobachtungen weisen darauf hin, dass bei Forschungen zur Aufklärung der Resistenzmechanismen, sowohl die Wirkung von Paraquat auf die Chloroplasten als auch einen nicht photosynthetiseh wirksamen Effekt auf das Zellwachstum berücksichtigen müssen.     

Determination of tau-fluvalinate residues in honey

A capillary column gas chromatographic method is described for the determination of tau-fluvalinate in honey samples. The method involves solid phase extraction of the sample with two RP C-8 cartridges in series, purification of the extract, if necessary, on a silica cartridge, and detection of the active ingredient with an electron capture detector. The method is rapid and overcomes the problem of emulsion formation in liquid/liquid partition often found in traditional systems. The detection limit in actual samples is 0.01 mg kg^?1 and mean recoveries for fortified samples prepared with or without clean-up are greater than 85%.     

Residues of zeta‐cypermethrin in bovine tissues and milk following pour‐on and spray application

The depletion of zeta‐cypermethrin residues in bovine tissues and milk was studied. Beef cattle were treated three times at 3‐week intervals with 1 ml 10 kg^?1 body weight of a 25 g litre^?1 or 50 g litre^?1 pour‐on formulation (2.5 and 5.0 mg zeta‐cypermethrin kg^?1 body weight) or 100 mg kg^?1 spray to simulate a likely worst‐case treatment regime. Friesian and Jersey dairy cows were treated once with 2.5 mg zeta‐cypermethrin kg^?1 in a pour‐on formulation. Muscle, liver and kidney residue concentrations were generally less than the limit of detection (LOD = 0.01 mg kg^?1). Residues in renal‐fat and back‐fat samples from animals treated with 2.5 mg kg^?1 all exceeded the limit of quantitation (LOQ = 0.05 mg kg^?1), peaking at 10 days after treatment. Only two of five kidney fat samples were above the LOQ after 34 days, but none of the back‐fat samples exceeded the LOQ at 28 days after treatment. Following spray treatments, fat residues were detectable in some animals but were below the LOQ at all sampling intervals. Zeta‐cypermethrin was quantifiable (LOQ = 0.01 mg kg^?1) in only one whole‐milk sample from the Friesian cows (0.015 mg kg^?1, 2 days after treatment). In whole milk from Jersey cows, the mean concentration of zeta‐cypermethrin peaked 1 day after treatment, at 0.015 mg kg^?1, and the highest individual sample concentration was 0.025 mg kg^?1 at 3 days after treatment. Residues in milk were not quantifiable beginning 4 days after treatment. The mean concentrations of zeta‐cypermethrin in milk fat from Friesian and Jersey cows peaked two days after treatment at 0.197 mg kg^?1 and 0.377 mg kg^?1, respectively, and the highest individual sample concentrations were 2 days after treatment at 0.47 mg kg^?1 and 0.98 mg kg^?1, respectively. © 2001 Society of Chemical Industry     

Chlorpyrifos-methyl plus bioresmethrin; Methacrifos; Pirimiphos-methyl plus bioresmethrin; and synergised bioresmethrin as grain protectants for wheat

Field trials with various pesticide combinations were carried out on bulk wheat in commercial silos in Queensland, South Australia and Western Australia. Laboratory bioassays on samples of treated grain at intervals over 8 months using malathion-susceptible and malathion-resistant strains established the following orders of efficacy: against Sitophilus oryzae (L.), chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = methacrifos 15 mg kg^?1 in aerated storage > pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1 = bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1; against Rhyzopertha dominica (F.), bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1 > methacrifos 15 mg kg^?1 > chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1. All treatments completely prevented production of progeny in Sitophilus granarius (L.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.). The biological efficacy of methacrifos was greater and the rate of degradation lower in aerated than in non-aerated storage. Residue levels of all compounds were determined chemically and were below proposed international residue levels to be considered by the Codex Alimentarius Commission.     

Measurement of simazine residues in chickpeas,Cicer arietinum,by gas–liquid chromatography

A method is described for the measurement of simazine [2-chloro-4,6-bis(ethylamino)-1,3,5-triazine] residues in chickpeas (Cicer arietinum). Ground chickpea samples were extracted with dichloromethane, followed by clean-up on alumina. Gas-liquid chromatography using metribuzin [4-amino- 6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one] as internal standard with thermionic detection was used to quantify simazine residues. The limit of detection was 0.02 mg kg^?1 and the recoveries of simazine from chickpea samples (0.1–4 mg kg-1) averaged 92%.     

Paraquat resistance in a biotype of Vulpia bromoides (L.) S. F. Gray

A biotype of Vulpia bromoides from a lucerne field in Elmhurst, Victoria, Australia was shown to be resistant to paraquat in pot trials. Application of paraquat at 50 g a.i. ha^?1 killed all of the plants of a susceptible Vulpia bromoides biotype but only 6% of the resistant biotype. The LD₅₀ for paraquat of the resistant biotype was five- to sixfold higher than for the susceptible biotype. The resistant biotype was also resistant to the bipyridyl herbicide diquat, but was susceptible to glyphosate and metribuzin. Application of 100 g a.i. ha^?1 paraquat at anthesis completely suppressed seed set of the susceptible biotype and reduced that of the resistant biotype by 95%. Seed set by the paraquat-treated resistant biotype, however, showed little reduction in germination. This is the fourth species to have been found to be resistant to bipyridyl herbicides in this field, the others being Hordeum glaucum, H. leporinum and Arctotheca calendula. Résistance au paraquat d'un biotype de Vulpia bromoides (L.) S. F. Gray Un biotype de Vulpia bromoides issu d'un champ de luzerne à Elmhurst, Victoria, Australie s'est révélé résistant au paraquat lors d'essais en pots. Des traitements au paraquat 50 g m.a. ha^?1 détruisaient toutes les plantes d'un biotype sensible de V. bromoides mais seulement 6% du biotype résistant. La DLV₅₀ du paraquat pour ce biotype était 5 à 6 fois plus élevée que pour le biotype sensible. Le biotype résistant l'était aussi à l'herbicide bipyridyle diquat, mais était sensible au glyphosate et à la métribuzine. Des traitements au paraquat 100 g m.a. ha^?1 au stade anthèse supprimaient complètement la production de graines du biotype sensible et réduisait de 95% celle du biotype résistant. Cependant, le pouvoir germinatif des graines issues du biotype résistant traité, n'était que peu réduit. Après Hordeum glaucum, Hordeum leporinum et Arctotheca calendula, c'est la quatrième espèce trouvée dans ce même champ résistante aux herbicides bipyridyles. Paraquatresistenz eines Biotyps von Vulpia bromoides (L.) S. F. Gray Ein Biotyp von Vulpia bromoides von einem Luzernefeld in Elmhurst, Victoria, Australien, erwies sich in Topfversuchen als paraquatresistent. Mit 50 g AS ha^?1 wurden Pflanzen eines empfindlichen Biotyps abgetötet, jedoch nur 6% des resistenten. Die LD₅₀ des resistenten Biotyps für paraquat war 5- bis 6mal höher als die des empfindlichen Biotyps. Der resistente Biotype war auch gegenüber dem Bipyridylherbizid Deiquat résistent, gegenüber Glyphosat und Metribuzin jedoch empfindlich. Nach Anwendung von 100 g AS ha^?1 Paraquat vor der Blüte bildeten sich bei dem empfindlichen Biotyp keine Samen aus, bei dem resistenten waren sie um 95% vermindert; die dennoch gebildeten Samen keimten etwas weniger. Dies ist die vierte Pflanzenart, bei der eine Resistenz gegenüber Bipyridylherbiziden beobachtet wurde, die anderen sind Hordeum glaucum. Hordeum leporinum und Arctotheca calendula.     

超高效液相色谱法测定土壤中多杀菌素和乙基多杀菌素的残留

建立了土壤中多杀菌素(spinosad)A和D以及乙基多杀菌素(spinetoram)J和L残留量的超高效液相色谱(UPLC)检测方法。土壤样品经乙腈-5%氯化钠溶液-1 mol/L氢氧化钾溶液提取,固相萃取柱净化,UPLC检测,外标法定量。结果表明:土壤中多杀菌素和乙基多杀菌素的定量限分别为0.1和0.05 mg/kg;最小检出量分别为8.0×10-7和2.8×10-7g;在0.1~2 mg/kg添加水平下,多杀菌素在土壤中的平均回收率为89%~96%,相对标准偏差(RSDs)为2.1%~4.9%;在0.05~0.5 mg/kg添加水平下,乙基多杀菌素在土壤中的平均回收率为86%~93%,RSDs为1.2%~8.1%。该方法提取效果好,具有良好的灵敏度、回收率和重复性。     

Organophosphorothioates and synergised synthetic pyrethroids as grain protectants on bulk wheat

Organophosphorothioates and synergised synthetic pyrethroids were used in duplicate field trials carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays using malathion-resistant strains of insects were carried out on samples of treated grain at intervals over 9 months. These established that all treatments were generally effective. Deltamethrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1), fenitrothion (12 mg kg^?1)+ fenvalerate (1 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1), fenitrothion (12 mg kg^?1)+ phenothrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) and pirimiphos-methyl (4 mg kg^?1)+ permethrin (1 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) controlled common field strains of Sitophilus oryzae (L.) and Rhyzopertha dominica (F.). Against a highly resistant strain of S. oryzae, deltamethrin (2 mg kg^?1)+ piperonyl butoxide (8 mg kg^?1) was superior to the remaining treatments. All treatment combinations completely prevented progeny production in Tribolium castaneum (Herbst), T. confusum Jacquelin du Val and in Ephestia cautella (Walker). Residues of deltamethrin, fenvalerate, permethrin and phenothrin were determined and shown to be highly persistent on stored wheat. During milling, residues accumulated in the bran fractions and were reduced in white flour. They were not significantly reduced during baking.     

Comparative purification methods for determination of triadimenol residues in plant material

Two procedures are described for the determination of residues of triadimenol and compared on cereal material. After extraction, purification is carried out by Florisil column chromatography in method I and by semi-preparative High-Performance Liquid Chromatography in method II. Triadimenol residues are quantified by gas chromatography with a thermoionic detector. With method I, interference was observed but not with method II. This specific procedure has been tested on other plant materials. Recoveries in the range of 90–98% indicate that this procedure is suitable for residue analysis of this fungicide with detection limits of 0·008 mg kg^?1 in wheat grains, 0·03 mg kg^?1 in wheat straw and 0·004–0·008 mg kg^?1 in other plants. Maximum residue limits in France are: 0·1 mg kg^?1 in grain, 2·0 mg kg^?1 in straw and 1·0 mg kg^?1 in other vegetables and fruit.     

Paraquat-resistant biotypes of Hordeum glaucum from zero-tillage wheat

There has been a significant increase in the area seeded to minimum- and zero-tilled crops worldwide over the past two decades. These cropping systems rely primarily on the non-selective herbicides glyphosate or paraquat/diquat to control weeds before seeding the crop. Both glyphosate and paraquat/diquat are regarded as low-risk herbicides in the ability of target weeds to develop resistance to them. Following 10–15 years of once annual applications of paraquat and diquat for weed control in zero-tilled cereals, failure of these herbicides to control Hordeum glaucum Steud. in two separate fields occurred. Dose–response experiments demonstrated high-level resistance to paraquat and diquat in both populations; however, the resistant biotypes are susceptible to other herbicides. This is the first report, worldwide, of paraquat resistance following the use of this herbicide in zero-tillage cropping systems and is therefore a harbinger of future problems in minimum-tillage systems when there is exclusive reliance on a contact herbicide for weed control.     

Determination of residues of endosulfan and endosulfan sulfate on eggplant,mustard and chickpea

Extractable residues of endosulfan stereoisomers and its toxic metabolite, endosulfan sulfate, on a vegetable, an oilseed and a pulse crop were determined by gas-liquid chromatography. The study revealed that the alpha isomer degraded faster than the beta isomer. Beta-endosulfan accumulated during the first three days following the treatment. Endosulfan sulfate residues appeared a few days after application and decreased with time. The total endosulfan residues in the seeds from treated mustard ranged from 0.08 to 0.12 mg kg^?1 and were at or below the limit of determination (0.02 mg kg^?1) in chickpea seeds following harvest.     

Determination of diquat residues in rape seeds

A method for the determination of diquat residues in rape seeds has been developed. It is based on the original procedure of Calderbank, Morgan and Yuen¹ as modified by Kirsten² for diquat residues in potato tubers, which includes acid hydrolysis, ion exchange clean-up, colour formation and spectrophotometry. When applied to rape seeds the background was too high. Ion pair extraction with bromthymol blue in dichloromethane removed most interfering substances. Measurement of absorbance at three wavelengths 10 nm apart increased the specificity further. Because of varying recoveries from rape seeds (range 35-60%) in the procedure isotope dilution analysis was applied to each sample. The limit of detectability at 40-50 % recovery in a 20 g sample is 0.07 mg/kg and in a 50 g sample 0.03 mg/kg. The application to field trials is illustrated.     

Gas-liquid chromatographic determination of hydrazine in maleic hydrazide formulations and in samples stored at an elevated temperature

A method is described for the analysis of small amounts of hydrazine in maleic hydrazide formulations. Following derivative formation with pentafluorobenz-aldehyde, the pentafluorobenzaldehyde azine was extracted with hexane and determined by gas-liquid chromatography with electron-capture detection. Recoveries of 72-80% were obtained from samples fortified with 1 and 10 μg of hydrazine. The limit of detection was 0.05 mg kg^?1. Fourteen commercial formulations with maleic hydrazide concentrations ranging from 180-360 g litre^?1 were investigated. The hydrazine content of the maleic hydrazide used in these formulations ranged from less than 0.05 to 53 mg kg^?1. During the storage of two samples at 50°C for 10 weeks, the hydrazine contents increased from 2.2 to 124 and 0.4 to 54 mg litre^?1, respectively.