Diethyldithiocarbamate, spectrophotometric

Silver diethyldithiocarbamate [1470-61-7] is a reagent commonly used for the spectrophotometric measurement of arsenic in aqueous samples (51) and for the analysis of antimony (52). Silver iodate is used in the determination of chloride in biological samples such as blood (53). 

Discussion. Sodium diethyldithiocarbamate (B) reacts with a weakly acidic or ammoniacal solution of copper(II) in low concentration to produce a brown colloidal suspension of the copper(II) diethyldithiocarbamate. The suspension may be extracted with an organic solvent (chloroform, carbon tetrachloride or butyl acetate) and the coloured extract analysed spectrophotometrically at 560 nm (butyl acetate) or 435 nm (chloroform or carbon tetrachloride). 

The following procedure has been recommended by the Analytical Methods Committee of the Society for Analytical Chemistry for the determination of small amounts of arsenic in organic matter.20 Organic matter is destroyed by wet oxidation, and the arsenic, after extraction with diethylammonium diethyldithiocarbamate in chloroform, is converted into the arsenomolybdate complex the latter is reduced by means of hydrazinium sulphate to a molybdenum blue complex and determined spectrophotometrically at 840 nm and referred to a calibration graph in the usual manner. 

Yang et al. [588] have described a spectrophotometric method for the determination of dissolved titanium in seawater after preconcentration using sodium diethyldithiocarbamate. See also Sect. 5.74.14. 

Sodium diethyldithiocarbamate (Na-DDTC, formula 4.40) is the dithiocarbamate most commonly used in spectrophotometric analysis [96-98]. 

Spectrophotometric methods using Na-DDTC are rather insensitive since the colours of metal complexes with DDTC are not intense. Complexes with Cu, Bi, and Mn are among the most intensely coloured diethyl dithiocarbamates. The yellowish Ag-DDTC is used in the determination of arsenic (reaction with ASH3, see Section 8.2.2). Fig. 19.1 shows the absorption spectra of some metal diethyldithiocarbamates. 

A spectrophotometric technique has been used for quantifying pg/mL levels of free and acid-labile (chemically bound) carbon disulfide in the blood of rats (Lam and DiStefano 1982, 1983). This technique is based on measuring the absorbance at 430 nm of a yellow cupric diethyldithiocarbamate complex that is formed by reacting carbon disulfide in blood with Viles reagent in the presence of acid and heat. A headspace sampler connected to GC equipped with a sulfur-specific flame photometric detector (FPD) has been developed for measuring low levels of free and acid-labile carbon disulfide in the blood of shift workers exposed to carbon disulfide (Campbell et al. 1985). A detection limit of 15.2 pg of carbon disulfide/L of blood was achieved. Concentrations of free and acid-labile carbon disulfide have also been determined by GS/MS (Brugnone et al. 1993, 1994 Perbellini et al. 1994). 

Quantitative. Classically, silver concentration in solution has been determined by titration with a standard solution of thiocyanate. Ferric ion is the indicator. The deep red ferric thiocyanate color appears only when the silver is completely titrated. Gravimettically, silver is determined by precipitation with chloride, sulfide, or 1,2,3-benzotriazole. Silver can be precipitated as the metal by electrodeposition or chemical reducing agents. A colored silver diethyldithiocarbamate complex, extractable by organic solvents, is used for the spectrophotometric determination of silver complexes. 

Spectrophotometric determination. The airborne aerosol is filtered and after the filter mineralization, arsenic compounds are reduced with zinc in HCl medium to arsine. Arsine with a solution of silver diethyldithiocarbamate in pyridine yields a red colour, which is suitable for spectrophotometric determination. The measurement is made at 540 nm [26]. 

The ligand substitution reactions of the bivalent first-row transition metal ions are the most studied of those of the labile metal ions, probably because the visible d-d spectra of the transition metal ions make them particularly amenable to spectrophotometric study, and also because their reaction timescale is usually well within those of the SF and NMR techniques. Thus it has been shown that the mechanism of dimethylformamide (dmf) exchange on [M(dmf)6] (M = Mn—Ni) varies systematically from L to D, in contrast to the analogous [M(solvent)6] in water, methanol, and acetonitrile where the mechanism varies from L h the number of d electrons increases. This has occasioned a spectrophotometric SF study of the closely related substitution of the bidentate ligands trans-pyndine-2-azo(p-dimethylaniline) (Pada) and diethyldithiocarbamate (Et2DTC) on [M(dmf)6] shown in Eq. (13) (where L-L represents a bidentate ligand) which... 

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