Determination of ziram in vegetable samples by square wave voltammetry

The electrochemical behaviour and electrode reaction mechanism of ziram （zinc-dimethyl dithiocarbamate） on a hanging mercury drop electrode were investigated in Britton-Robinson （B-R） buffer by using cyclic and square wave voltammetry （SWV）. Based on these studies a voltammetric method for determination of ziram wasdeveloped and applied to determine the ziram in synthetic and spiked vegetable samples, satisfactory results were obtained in both cases.     

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.     

A sensitive spectrophotometric method for the determination of dithiocarbamate fungicide and its application in environmental samples

A sensitive spectrophotometric method based on the evolution of CS₂ and colour development by leuco crystal violet is described for the determination of dithiocarbamate fungicides, e.g. thiram, ziram and zineb. Dithiocarbamate fungicides release CS₂ on acid hydrolysis. This CS₂ is absorbed in ethanolic sodium hydroxide and forms xanthate. The xanthate formed is subsequently treated with potassium iodate and N-chlorosuccinimide, during which free iodine is liberated. Crystal violet dye was formed through selective oxidation of leuco crystal violet by liberated iodine, which has an absorbance maxima at 595 nm. The colour systems obey Beer's law in the range of 0.02–0.20, 0.02–0.24 and 0.04–0.32 ppm for thiram, ziram and zineb respectively. The molar absorptivity of the colour system were found to be 9.6×10⁵, 1.1×10⁶ and 6.8×10⁵±100 l mol⁻¹ cm⁻¹ for thiram, ziram and zineb respectively. The method has been successfully applied to the determination of these dithiocarbamate fungicides in various environmental samples.     

Chromatographic Behavior of Dithiocarbamate Fungicides on Cellulose Plates

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of the dithiocarbamate fungicides mancozeb, NaDDC, propineb, ziram, and zineb has been studied on TLC...     

Spectrophotometric determination of some dithiocarbamates

A procedure has been developed for the determination of six dithiocarbamates [sodium dimethyldithiocarbamate (dibam), sodium diethyldithiocarbamate (NaDDC), tetramethylthiuram disulphide (thiram), zinc dimethyldithiocarbamate (ziram), sodium N-methylpiperazinecarbodithioate and potassium morpholine-4-carbodithioate] in microgram quantities by converting them into selenium dithiocarbamate complexes, which are then extracted into chloroform and measured at 430 nm against a reagent blank. The method is sensitive and can be used for the determination of dithiocarbamates in commercial samples and synthetic mixtures.     

Quantification of ziram and zineb residues in fog-water samples

The present paper describes the extractive quantification of zinc-dithiocarbamate fungicides, i.e. ziram (zinc bis-dimethyldithiocarbamate) and zineb (zinc ethylene-1,2-bis-dithiocarbamate) in fog-water samples. The method is based on the releasing of equivalent amount of zinc from the fungicides and its subsequent determination by visible spectrophotometry or by flame-atomic absorption spectrometry (flame-AAS). For spectrophotometry, the sample contained up to 48 μg of ziram and 42 μg of zineb was first equilibrated with chloroform. The recovery results show that only ziram content was extracted into chloroform. Then, the sample was treated with NH₄SCN and surfactants (i.e. CPC and TX-100) solutions, and extracted with toluene to remove interference of inorganic zinc and other metal ions, if present in the sample. The residue was further used for zineb determination. The chloroform extract and residue were then digested separately with nitric acid to release Zn(II), which were then analyzed spectrophotometerically with 4-(2-pyridylazo)-resorcinol in the micellar medium (TX-100) for the determination of ziram and zineb, respectively. The complex shows λ_max at 495 nm. The molar absorptivity in terms of ziram/zineb was determined to be (8.05) × 10⁴ L mole⁻¹ cm⁻¹. The detection limits for ziram and zineb were calculated to be 20 and 21 μg L⁻¹ (with R.S.D. < 1.5%), respectively. Whereas, the optimum concentration ranges were 0.08-1.6 and 0.07-1.4 mg L⁻¹, respectively. Alternatively, the Zn contents present in chloroform extract and in residue were directly analyzed using flame-AAS without undergoing the digestion procedure, and ziram and zineb were determined, respectively. The optimum concentration ranges were 0.9-4.8 and 0.8-4.3 mg L⁻¹, while the detection limits were calculated to be 145 and 144 μg L⁻¹, respectively with R.S.D. < 2.5%. The methods are free from interference of almost all ions [including Zn(II)] and other dithiocarbamate pesticides, which can commonly associate with ziram/zineb in fog-water.     

Flow injection-photoinduced-chemiluminescence determination of ziram and zineb

A simple, sensitive and rapid method for the determination of the pesticides ziram and zineb was described. This new method was based on the coupling of FIA methodology and direct chemiluminescent detection; this approach had not been used up to now with these pesticides. The additional use of an ‘on line’ photochemical reaction, which was performed by using a photoreactor consisting of a long piece of PTFE helically coiled around a 15 W low-pressure lamp, increased by a factor >20 the chemiluminometric response of the pesticides. An additional 3-fold improvement in the analytical signal was also achieved by using quinine as sensitizer. The obtained throughputs were very high (121 and 101 h⁻¹ for ziram and zineb, respectively); this feature together with its low limit of detection (1 ng mL⁻¹) makes this method particularly well suited to routine analyses of environmental samples. On the other hand, its applicability to two members of the dithiocarbamate family of pesticides, makes it promising for the determination of the rest of the members of this family. The method was demonstrated by application to spiked water samples from different origins (ground, river and irrigation).     

A combination of dispersive liquid–liquid microextraction and surface plasmon resonance sensing of gold nanoparticles for the determination of ziram pesticide

We have developed a reliable, fast, and highly sensitive analytical method utilizing dispersive liquid–liquid microextraction and gold nanoparticles probes for ziram (zinc bis(dimethyldithiocarbamate)) determination. The method is based on the in situ formation of gold nanoparticles in carbon tetrachloride as an organic phase. It was found that the trace levels of ziram influenced the formation of gold nanoparticles, leading to absorbance change of a sedimented phase. The results of the colorimetric ziram determination were in the concentration range of 0.12–2.52 ng/mL with a limit of detection of 0.06 ng/mL. The formation of the stable and dispersed gold nanoparticles in the organic phase provides a good precision for dispersive liquid–liquid microextraction method, resulting in the relative standard deviation of 3.8 and 1.2% for 0.56 and 1.58 ng/mL of ziram, respectively. This method has been successfully used for the ziram determination in samples of well and river water, soil, potato, carrot, wheat, and paddy soil.     

Selective trace determination of dithiocarbamate fungicides in fruits and vegetables by reversed-phase ion-pair liquid chromatography with ultraviolet and electrochemical detection

The predominant methods for determination of dithiocarbamate fungicides (DTC) have been based on quantitation of carbon disulfide released by hot acid digestion. Because the subgroups of the DTC family differ in their chemical properties and toxicological behavior, selective determination is required. To meet the demand for a fast, simple, and sensitive procedure, a new reversed-phase ion-pair chromatographic method was developed, consisting of surface extraction followed by direct injection into a liquid chromatographic system equipped with ultraviolet and electrochemical detectors, connected in series. The procedure is applicable to residues of N-methyldithiocarbamates (metam-sodium), N,N-dimethyldithiocarbamates (e.g., ziram and ferbam), ethylenebisdithiocarbamates (e.g., nabam, maneb, zineb, and mancozeb), and propylenebisdithiocarbamates (e.g., propineb) in fruits and vegetables. Limits of quantitation, calculated according to the procedure of the Deutsche Forschungsgemeinschaft, are 9, 12, 8, and 12 microg CS2/L for N-methyl-DTC, N,N-dimethyl-DTC, ethylenebis-DTC, and propylenebis-DTC, respectively, when electrochemical detection is used.     

Spectrophotometric determination of zinc bis-ethylenedithiocarbamate (zineb)

A spectrophotometric method has been developed for the determination of zineb by converting it into a molybdenum ethylenedithiocarbamate complex, which is then extracted into isobutyl methyl ketone and measured at 670 nm against a reagent blank. Beer's law is obeyed over the zineb concentration range 2-40 mug/ml in the extract. The method is sensitive and can be used for determination of zineb in the presence of ziram, thiram or ferbam.     

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.     

Differential pulse anodic stripping voltammetric determination of ziram (a dithiocarbamate fungicide)

A d.c. polarographic technique has been used previously for the determination of the pesticide, ziram, in aqueous samples, this paper reports differential pulse anodic stripping voltammetric determination of ziram zinc in rice samples using a static mercury drop electrode. The procedure developed distinguishes inorganic zinc and ziram zinc in sodium acetate-sodium chloride media. The procedure developed is suitable for the determination of concentrations as low as 10 ppb of ziram with a precision of 2.1% for five successive determinations of 150 ppb of ziram.     

Spectrophotometric determination of copper(II) with carbon disulfide,a secondary amine and triton X-100

Copper(II) is determined by non-extractive spectrophotometry as a complex of butylene dithiocarbamate formed in situ by reaction between carbon disulfide and pyrrolidine in aqueous Triton X-100 medium. This method is similar to that with butylene dithiocarbamate as starting material in the sense of simplicity, sensitivity, precision and accuracy. Pyrrolidine is the best of seven secondary amines tested in this way for copper determinations.     

高效液相色谱-二极管阵列检测法测定小麦粉及面粉改良剂中福美双

福美双是重要的二硫代氨基甲酸酯(DTC)杀菌剂,在小麦中使用限量以1 mg/kg二硫化碳(CS₂)计。目前我国相关检测方法是针对二硫代氨基甲酸酯一类的化合物,二硫代氨基甲酸酯通过与酸反应生成CS₂,采用光谱法或色谱法测定CS₂,间接实现二硫代氨基甲酸酯测定。该方法无法特异性实现对福美双的检测,因此开展小麦粉中福美双检测方法的研究具有重要意义。研究建立了高效液相色谱-二极管阵列检测(HPLC-DAD)测定小麦粉及面粉改良剂中福美双的分析方法。小麦粉及面粉改良剂样品用乙腈溶剂提取后,经涡旋、振荡、冰水浴超声和静置后取上清液过滤,供高效液相色谱测定。采用ZORBAX plus-C18色谱柱(150 mm×4.6 mm, 5 μm)分离,以水-乙腈为流动相洗脱分析,在波长280 nm下检测。实验优化了提取溶剂及其体积、振荡超声条件、色谱柱、检测波长、流动相等条件。该方法采用保留时间和紫外光谱图定性,外标法定量。该方法在线性范围内(0.30~30.0 μg/mL)线性关系良好,相关系数(r²)为0.99999。对小麦粉及面粉改良剂进行1.5、3.0、15 mg/kg 3个水平的加标回收试验,福美双的回收率为89.6%~98.3%,相对标准偏差为1.6%~3.9%(n=6)。方法的检出限和定量限分别为0.5 mg/kg和1.5 mg/kg。该方法采用溶剂提取,操作简单,分析时间短,特异性好,具有精密度高、重复性好、检出限低等特点,适用于小麦粉及面粉改良剂中福美双快速、准确的定量检测。     

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.     

Thermodynamics of adsorption of dithiocarbamates at the hanging mercury drop

Two dimethyldithiocarbamate (DMDTC) pesticides, thiram and ziram, are adsorbed onto a Hg drop via an entropically driven process. The adsorption isotherms are described by the Frumkin equation. For both molecules, the adsorption is characterized by a nonlinear pseudosigmoid temperature dependence of the Gibbs free energy. For the temperature range of 273-313 K, DeltaGADS varies between -43.4 and -56.71 kJ/mol for thiram and -42.60 and -55.67 kJ/mol for ziram. This variation of DeltaGADS reveals that the adsorption strength is increased at higher temperatures. During the adsorption of either molecule, strong lateral interactions are developed between neighboring adsorbates, which are severely weakened as the temperature increases. A unified reaction scheme is suggested for both ziram and thiram that predicts the formation and adsorption of a surface complex, (DMDTC)2Hg. In the case of thiram, two DMDTC molecules are formed by the cleavage of the disulfide S-S bond near the Hg electrode. The thermodynamic and structural parameters reveal that there are two limiting thermodynamic regimes for the adsorbed (DMDTC)2Hg species that originate from two limiting adsorption conformations of the adsorbates on the Hg surface. A transition occurs between these two conformations at temperatures in the region of 285-295 K. This transition is accompanied by large entropic and enthalpic changes.     

Application of chalcone-based dithiocarbamate derivative incorporated sol–gel for the removal of Hg (II) ion from water

Journal of Sol-Gel Science and Technology - This study demonstrated the application of chalcone-based dithiocarbamate derivative as metal capturing ligand for the removal of mercury ion (Hg2+) in...     

Comparison of chelating agents immobilized on glass with chelex 100 for removal and preconcentration of trace copper(II)

Three types of chelating agents immobilized on glass were compared with Chelex 100 for removing and preconcentrating trace Cu(2+) from laboratory-prepared solutions. Columns of immobilized N-propylethylenediamine (diamine), its bis(dithiocarbamate) (DTC) and immobilized 8-hydroxyquinoline (8-HQ) quantitatively remove Cu(2+) (10-200 mug l. ) from buffered solutions at pH 6.00. Addition of isolated natural organic matter at concentrations typical of organic-rich fresh waters (25-100 mug l. ) complexed Cu(2+) and hindered the performance of Chelex and the immobilized chelating agents. In the presence of organic matter the DTC performed very well, removing about 98% of the Cu(2+). However, the Cu(2+) removed could not be readily recovered from the column. Chelex gave the poorest results, removing only 62 and 75% of Cu(2+) at the two levels tested. The other immobilized reagents gave results that were strongly dependent on their contact time with the solution. Longer columns and slower flow-rates tended to improve results. Overall, the immobilized 8-HQ is probably the most suitable of the materials tested for preconcentration work. A batch titration of 8-HQ with Cu(2+) monitored by ion-selective electrode indicated a conditional stability constant of 6.2 x 10(7), which is larger than the corresponding value for the complex with non-immobilized 8-hydroxyquinoline, measured under the same conditions.     

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.     

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.