Spectrophotometric determination of ziram, ferbam and zineb with diphenylcarbazone

A procedure has been developed for the determination of ziram (zinc dimethyldithiocarbamate), ferbam (ferric dimethyldithiocarbamate) and zineb (zinc ethylenebisdithiocarbamate) after their decomposition and extraction of the diphenylcarbazone complexes of the zinc or iron into isobutyl methyl ketone. These complexes absorb strongly at 520 nm. The method is rapid, sensitive and selective and can be used for the determination of these dithiocarbamates in commercial and synthetic mixtures.     

Fourth-derivative spectrophotometric determination of fungicide ferbam (iron(III) dimethyldithiocarbamate) in a commercial sample and wheat grains using 2,2′-bipyridyl

A procedure has been developed for the direct fourth-derivative spectrophotometric determination of iron(III) dimethyldithiocarbamate by converting it into an iron(II) 2,2'-bipyridyl complex, which is then dissolved in Triton X-100. Beer's law is obeyed over the concentration range 0.5-20 microg mL(-1 )in the final solution. Various parameters such as the effect of pH and interference of large number of ions on the determination of ferbam have been studied in detail. The method is sensitive, highly selective and can be used for the determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and from wheat grains.     

Determination of the fungicide ferbam in wheat grains after adsorption onto microcrystalline naphthalene

A procedure was developed for the determination of iron(III) dimethyldithiocarbamate by converting it into iron(II)-bathophenanthroline-tetraphenylborate complex, which was then adsorbed onto microcrystalline naphthalene. The absorbance was measured at 534 nm against a reagent blank. Beer's Law was obeyed over the concentration range of 0.4-20 microg mL in final solution. Ten replicate determinations on 70 microg ferbam solutions gave a mean absorbance of 0.36, with a relative standard deviation of 0.91%. The method is sensitive and highly selective. It was applied for the determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb) and wheat grains.     

Spectrophotometric determination of iron(III) dimethyldithiocarbamate (ferbam)

A spectrophotometric method was developed for the determination of ferbam (iron(III) dimethyldithiocarbamate) by converting it into an iron-phenanthroline complex, which was then absorbed on microcystalline naphthalene in the presence of tetraphenylborate, and the absorbance was measured at 515 nm against a reagent blank. The molar absorptivity of the complex was 1.2 x 10(4)l mol(-1)cm(-1). Ten replicate analyses of a sample solution containing 150 mug of ferbam gave a relative standard deviation of 0.84%. Beer's law was obeyed over the concentration range 22.4-372.9 mug of ferbam. The effects of various factors such as reagent concentration and naphthalene, shaking time and diverse ions were studied in detail. The method is sensitive and selective and can be applied to the direct determination of ferbam in commercial samples and in mixtures containing various other dithiocarbamates (e.g. ziram, zineb and maneb) in foodstuffs.     

Spectrophotometric Determination of Ziram by Coprecipitating the Corresponding Copper(II) or Palladium(II) Complex with Naphthalene

A spectrophotometric method has been developed for the determination of zinc dimethyldithiocarbamate (ziram) by converting it into dimethyldithiocarbamate and coprecipitating its copper(II) and palladium(II) dimethyldithiocarbamate complexes and coprecipitating onto microcrystalline naphthalene. Palladium(II) and copper(II) complexes absorb strongly at 395 nm and 430 nm, respectively. The interference of various ions has been studied and the method has been applied to determine ziram in commercial samples and grains.     

Fourth derivative spectrophotometric determination of fungicide ziram (zinc(II) dimethyldithiocarbamate) in commercial samples and wheat grains

A procedure has been developed for the direct fourth derivative spectrophotometric determination of zinc(II) dimethyldithiocarbamate by converting it into its copper(II) dimethyldithiocarbamate complex, which is then dissolved in Triton X-100. Beer's law is obeyed over the concentration range 0.5–30?µg/mL in the final solution. Various parameters such as the effect of pH and the interference of a number of ions on the determination of Ziram have been studied in detail. The method is sensitive and can be used for the determination of Ziram in commercial samples like Zirax and Ziron containing Ziram and from wheat grains.     

Non-aqueous cerimetric determination of dithiocarbamates and its application to the determination of amines

A non-aqueous titrimetric method for determination of dithiocarbamates with cerium(IV), is described. The compounds are titrated at room temperature, with visual and potentiometric end-point detection. In visual titrations, the reagent serves as self-indicator and turns the solution yellow at the end-point. Methyl Red can also be used as the indicator. The method has been applied to the determination of amines after their quantitative conversion into dithiocarbamates by reaction with carbon disulphide. The proposed method is accurate to +/- 0.8% with a relative standard deviation of +/- 0.7%.     

Determination of dithiocarbamate fungicide residues by liquid chromatography/mass spectrometry and stable isotope dilution assay

A rapid and very sensitive high-performance liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) method for the simultaneous determination of dithiocarbamate (DTC) fungicide residues in fruits and vegetables was developed. The surface extraction of samples used an alkaline buffer consisting of sodium hydrogen carbonate and DL-penicillamine. The three DTC subclasses, i.e. dimethyldithiocarbamates (DMDs), ethylenebis(dithiocarbamates) (EBDs), and propylenebis(dithiocarbamates) (PBDs), were separated on a Sequant ZIC-pHILIC column using an acetonitrile/10 mM ammonia gradient. Because of the instability of DTC residues extracted from plant samples, a stable isotope dilution assay was applied. For each DTC subclass, the limits of detection and quantification were approximately 0.03 mg kg(-1) and 0.05 mg kg(-1), respectively. Recoveries from grapes, cucumbers, tomatoes, and rucola, spiked in the range of 0.01-0.9 mg kg(-1), averaged between 90 and 100%.     

Photochemical reactions of quaternary ammonium dithiocarbamates as photobase generators and their use in the photoinitiated thermal crosslinking of poly(glycidyl methacrylate)

The photochemical behavior of quaternary ammonium salts (QA salts) with N,N‐dimethyldithiocarbamate as photobase generators and the photoinitiated thermal crosslinking of poly(glycidyl methacrylate) (PGMA) with the QA salts were investigated. The formation of basic compounds in the photolysis of 1‐phenacyl‐(1‐azonia‐4‐azabicyclo[2,2,2]octane) N,N‐dimethyldithiocarbamate was ascertained by the color change of phenol red as an acid–base indicator. ¹H NMR spectra of photoproducts in CDCl₃ under N₂ showed that the photolysis of 1‐naphthoylmethyl‐(1‐azonia‐4‐azabicyclo[2,2,2]octane) N,N‐dimethyldithiocarbamate resulted in the quantitative formation of triethylenediamine and a dithiocarbamate derivative. The presence of oxygen in the photolysis decreased the photolysis rate. The amine was also detected in its photolysis in polystyrene films. The effects of ammonio groups and counteranions of QA salts on the photoinitiated thermal crosslinking of PGMA films were also investigated. Quaternary ammonium dithiocarbamates acted as excellent photobase generators and effective photoinitiated thermal crosslinkers for PGMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1329–1341, 2001     

A highly selective diethyldithiocarbamate extraction system in activation analysis of copper,indium, manganese and zinc

A versatile separation system based on the extraction of dithiocarbamates and applicable to the determination of copper, managanese, zinc and indium in a wide selection of materials by activation analysis is described. After the dissolution of the sample and a few simple operations which eliminate specific interferences, depending upon the material (e. g. sodium and gold in the NBS Standard Reference Glasses), carbamates are extracted under specific conditions by addition of appropriate complexing agents and selective stripping. Extreme separation factors permit interference-free counting using a sodium iodide detector. For example, indium is separated from a hundred thousand fold excess of manganese in the determination of the two elements in Orchard Leaves. Results are also presented for all four elements in Bowen's Kale, NBS Bovine Liver, and for Cu, In and Mn in the 0.02 ppm and 1 ppm SRM glasses.     

Analytical applications of copper(II) and copper(I) in acetonitrile: potentiometric and spectrophotometric determination of dithiocarbamates

The use of copper(II) perchlorate and tetra-acetonitrilocopper(I) perchlorate (in acetonitrile) for the potentiometric and spectrophotometric determination of dithiocarbamates in acetonitrile medium is described. The proposed methods are simple, accurate and reliable and show promise of wide applicability. They are recommended for routine determination of dithiocarbamates. Their advantages over the carbon disulphide evolution method, commonly employed for the determination of these compounds, are discussed.     

Spectrophotometric determination of Zineb (a dithiocarbamate fungicide) by the methylene blue method

Summary A spectrophotometric method has been developed for the determination of Zineb in water and vegetables. The method is based on the liberation of hydrogen sulphide from Zineb, which is trapped in an absorbing solution of triethanolamine, sodium hydroxide and ethylenediamine tetraacetic acid. The absorbing solution is treated with N-N-dimethyl-p-phenylene diamine sulphonate and ferric chloride to form methylene blue. Beer's law is obeyed over the concentration range of 3–32 ppm. The method is simple and can be used for the determination of Zineb in the presence of other dithiocarbamates.     

Spectrophotometric determination of ziram in a commercial sample and wheat by extraction of its copper dimethyldithiocarbamate complex into molten naphthalene

A method was developed for the determination of zinc(II) dimethyldithiocarbamate by converting it into the copper(II) dithiocarbamate complex, which is then extracted into molten naphthalene. The absorbance is measured at 430 nm versus a reagent blank. Beer's law is obeyed for concentrations of 0.63 x 10(-3) to 17.2 x 10(-3) g/L in the final solution. The method is sensitive and was applied to the determination of ziram in a commercial sample and in wheat grain.     

Analytical applications of the amine-carbon disulphide reaction in acetonitrile

The ease with which carbon disulphide transforms primary and secondary amines in acetonitrile medium into the corresponding monoalkylammonium monoalkyldithiocarbamates and dialkylammonium dialkyldithiocarbamates respectively and the simplicity and reliability of potentiometric and spectrophotometric determination of dithiocarbamates with copper(I) perchlorate in the same medium, provide simple, accurate and reliable methods for the determination of primary and secondary amines and of organic isothiocyanates.     

Direct reaction of meta powders with several sodium dithiocarbamates

Copper and nickel powders react directly with sodium dithiocarbamates in organic solvents and produce the corresponding metal complexes. The rate constants have been estimated spectrohotometrically. The effects of organic solvents and substituents of the carbamates on the relative reactivity were studied. The results show that copper powder reacts in chloroform more readily than any other system examined. This reaction has been successfully applied to the determination of copper contents in brass and bronze powders.     

Determination of some dithiocarbamates by catalytic thermometric titration

The determination of dithiocarbamates by catalytic thermometric titration is described. The dithiocarbamates can be determined in the range 0.5-20 mumole with relative errors of about 5%.     

Evaluation of long chain dithiocarbamates as photometric reagents for the determination of trace amounts of uranium

A highly sensitive extractive spectrophotometric method for the determination of U(VI) using octadecyldithiocarbamate (ODDTC) has been developed. The efficiency of ODDTC as a chelating agent is compared with that of hexadecyl, tetradecyl and dodecyl dithiocarbamates. U(VI) reacts with these dithiocarbamates in ethanol to form reddish-brown water-insoluble chelates capable of being extracted into CHCl₃. The molar absorptivities range from 1.16·10 to 4.91·10⁴l·mol^–1·cm^–1, the highest value being found for ODDTC. Suitable conditions for the extraction and the effect of foreign ions were investigated. The method can be used for the determination of trace amounts of U(VI) in water and sand. The results are comparable to ICP-AES method.     

A new method for the synthesis of dithiocarbamates by CuI-catalyzed coupling reaction

The Ullmann-type coupling reaction of sodium dithiocarbamates with aryl iodides and vinyl bromides catalyzed by CuI/N,N-dimethylglycine proceeds smoothly in DMF at 110 °C to give corresponding dithiocarbamates in good yields.     

Hypervalent Iodine in Synthesis XXXV: A Simple and Convenient Stereospecific Synthesis of Vinyl Esters of Dithiocarbamic Acids

Vinyl esters of dithiocarbamic acids have been stereospecifically prepared by the reaction of sodium dithiocarbamates with vinyi(phenyi)iodonium tetrafluoroborates with retention or inversion of the configurations.     

Determination of Cd, Co, Cu, Fe and Ni at parts per billion level in high-purity gallium by graphite furnace atomic absorption spectrometry (GFAAS)

Summary The determination of Cd, Co, Cu, Fe and Ni in 6N gallium by GFAAS is reported. The analytes are extracted as pyrrolidine dithiocarbamates into methyl-iso-butyl-ketone (MIBK) in the presence of tartrate. The conditions of extraction, quantity of reagents required and the matrix interference aspects are discussed. The method offers one-step matrix removal and preconcentration, leading to low experimental blanks.