Determination of disulfiram and metabolites from biological fluids by high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the determination of disulfiram, diethyldithiocarbamate, diethyldithiocarbamate methyl ester, carbon disulfide, and diethylamine from a single sample of plasma or urine. The analytical procedure is based on a quantitative stepwise extraction of disulfiram and diethyldithiocarbamate methyl ester, or the conversion of diethyldithiocarbamic acid, carbon disulfide and diethylamine to diethyldithiocarbamate methyl ester for chromatographical determination. The procedure is specific, precise and simple. The application of the analytical methods developed for the determination of disulfiram and the various metabolites in plasma from mice given disulfiram intraperitoneally or humans given Antabuse orally is illustrated.     

Rapid and sensitive on-line precolumn purification and high-performance liquid chromatographic assay for disulfiram and its metabolites

The disulfiram (Antabus) metabolites diethyldithiocarbamate, diethyldithiocarbamate methyl ester, carbon disulphide and bis(diethyldithiocarbamato) copper complex were quantitatively analysed from directly injected heparin plasma by reversed-phase high-performance liquid chromatography. The highly volatile metabolite, carbon disulphide, was converted to the methyl ester of dimethyldithiocarbamate before chromatography. The analytical procedure is simple and does not require sample preparation or addition of an internal standard, and the compounds are eluted from the columns in 15 min. After automated on-line precolumn enrichment, the parent compound and biotransformation products could be back-flushed and chromatographed on an ordinary reversed-phase column. The influence of plasma protein binding on the constituents in the precolumn enrichment step was also investigated. Dissociation and partition of constituents from plasma proteins gave a complete retardation on the precolumn. The time courses of diethyldithiocarbamate and its methyl ester were followed in patients receiving therapeutic doses of disulfiram.     

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.     

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.     

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 disulfiram and two of its metabolites in urine by reversed-phase liquid chromatography and spectrophotometric detection after post-column complexation

A selective method was developed for the determination of disulfiram and two of its metabolites, diethyldithiocarbamate (DTC) and copper (II) diethyldithiocarbamate [Cu(DTC)2], in complex (biological) samples by reversed-phase liquid chromatography (RP-LC) with post-column derivatization. In the first step, DTC is converted into lead (II) diethyldithiocarbamate [Pb (DTC)2] by adding lead (II) acetate. Disulfiram, Pb (DTC)2 and Cu (DTC)2 can be easily pre-concentrated on C18-bonded silica. After separation by isocratic RP-LC, derivation takes place in two solid state post-column reactors packed with metallic copper and copper (II) phosphate. Disulfiram reacts with metallic copper to form Cu (DTC)2. The same product is obtained by the ligand-exchange reaction between Pb (DTC)2 and copper (II) phosphate. Cu (DTC)2 can be detected selectively at 435 nm with good sensitivity (molar absorptivity, epsilon = 13,000). The derivatization reactions proceed rapidly and quantitatively, which was confirmed by comparison of absorption spectra. The applicability of this method is demonstrated for undiluted urine samples which, apart from the addition of lead (II) acetate and pre-concentration of C18-bonded silica, require no clean-up procedure.     

Alkalimetric determination of mercaptans through trithiocarbonic acid formation

A simple and rapid alkalimetric method for the determination of mercaptans through trithiocarbonic acid formation is described. The mercaptans are titrated in tert.-butanol in the presence of carbon disulphide with standard aqueous sodium hydroxide, with phenolphthalein as indicator. The -SH group is smoothly, rapidly and quantitatively transformed into the group under the specified conditions. The method has been extended to the analysis of mercaptan-carboxylic acid and mercaptan-trithiocarbonate mixtures.     

Rapid determination of indium,nickel and copper in NBS standard reference material by substoichiometric radioactivation analysis

A method of rapid determination for indium, nickel and copper in Spinach (NBS; SRM-1570) by substoichiometric radioactivation analysis is described. The method is based on the principle that an equal amount of non-irradiated test sample is added to the irradiated standard sample and subsequent substoichiometric extraction for the irradiated test and standard samples is carried out. Indium is extracted as diethyldithiocarbamate into carbon tetrachloride, nickel as dimethylglyoximate into chloroform and copper as dithizonate into carbon tetrachloride. The radioactivities of these extracts are measured by NaI(Tl) or Ge(Li) detector coupled with pulse-height analyser. The analytical results obtained by the method were in good agreement with our published values and certified values by NBS.     

Spectrophotometric determination of carbon disulphide as the 1,2,3,4-thiatriazol-5-thiolate ion

A simple, precise and selective procedure for the spectrophotometric determination of carbon disulphide in water is described. The method is based on the quantitative formation of the 1,2,3,4-thiatriazol-5-thiolate ion from carbon disulphide and azide. The specific rate for this reaction at ionic strength 4.0 (NaN₃) and 25°C is 8.4·10^-3 mol^-1 s^-1; the kinetic parameters D3H and D3S are 16.7 kcal mol^-1 and —14 cal mol^-1deg^-1, respectively. At the analytical wavelength of 313 nm, the molar absorptivity is 7.27 ·10³ l mol^-1cm^-1. The system obeys Beer's law for 2.3–28.6 g ml^-1 of carbon disulphide. The effects of foreign ions are discussed.     

Redox reactions in non-aqueous media: determination of organic isothiocyanates alone, in formulations and in important mixtures

A simple potentiometric method for the determination of organoisothiocyanates is described. The isothiocyanate is treated in acetonitrile medium with an excess of primary amine to convert it into a substituted thiourea and the surplus amine is converted into a dithiocarbamate by addition of carbon disulphide. The solution is then titrated with a copper(II) solution in acetonitrile. The three-step titration curve enables the results to be calculated on the bash of the dithiocarbamate and/or thiourea formed. The method has been successfully applied to the analysis of a commercial insecticide formulation based on isothiocyanate and important mixtures containing isothiocyanates.     

Colorimetric uranium determination with arsenazo

A rapid and sensitive method is described for the quantitative colorimetric determination of uranium(Vl). Masking agents such as EDTA, tartaric acid or thioglycerol make possible the determination of uranium in the presence of many foreign metal ions. If thorium is present, a preliminary extraction of uranium as the diethyldithiocarbamate is required.     

A new colorimetric method for the determination of carbon disulphide and its application to the analysis of some dithiocarbamate fungicides

A new and convenient colorimetric method for determination of carbon disulphide, based on its transformation into bright yellow potassium benzyl trithiocarbonate through reaction with benzyl mercaptan and potassium hydroxide in tert.-butyl alcohol, has been successfully applied to determination of some dithiocarbamate fungicides in their formulations. The method possesses a distinct advantage in that it is free from all sources of errors/problems which are associated with the xanthate method for the analysis of these materials. The proposed method is precise and accurate and hence recommended for routine analysis of technical formulations containing dithiocarbamate fungicides.     

Determination of trace amounts of metals in saline water by energy dispersive XRF using the NaDDTC preconcentration

A simple method for the determination of trace concentrations of metals in saline water is described. The analytical procedure involves the separation of metal ions of Cu, Zn, Hg and Fe by precipitation with diethyldithiocarbamate (DDTC). The radioisotope X-ray fluorescence method using Si(Li) detector has been applied for the determination of metal ions closed in the DDTC deposition.     

A Radiochemical Method for Selective Determination of Traces of Lead

A very simple and rapid radiochemical method for the determination of 0.01—1 mcg of lead has been developed. It consists of adding carrier-free ^{2 1 2} Pb to the analysed sample, followed by shaking with a standard lead diethyldithiocarbamate solution in carbon tetrachloride. The amount of non-active lead in the sample is determined from activities of the organic and aqueous phases. A 10-fold excess of bismuth and more than 50–100-fold excess of other metals extractable as diethyldithiocarbamates do not interfere in the determination.     

示波极谱—铜试剂法测定巴比妥类药物的含量

采用示波极谱－ＤＤＴＣ（二乙基二硫代氨基甲酸钠，铜试剂）滴定法测定巴比妥类药物及其制剂的含量。该法到目前为止未见报道，它具有快速、准确、终点直观的特点，溶液的颜色、产生的沉淀、制剂中的赋形剂对滴定无影响，所测结果与药典法无显著差异。     

Determination of sulphur functions with N-iodosuccinimide

Titrimetric determination of thioureas, thiols, xanthates and dithiocarbamates with N-iodosuccinimide (NIS) is described. The method for xanthate can be applied to carbon disulphide (converted into xanthate with potassium ethoxide). Acidic and non-aqueous solutions of the oxidizing agent are stable. The procedures are rapid and accurate to 0.1% with a precision of 0.2%. Hydrogen sulphide and thiocarbonyl compounds interfere. The behaviour of N-bromosuccinimide and NIS with thiols in aqueous medium is compared. It is shown that iodine is the oxidizing species in both cases. The limitations of iodine as a reagent for thiol determination are discussed. Cysteine, which cannot be determined with iodine, can be determined with NIS. The role of methanol in non-aqueous determination of thiols is discussed. Methanol accelerates the oxidation, which is otherwise slow in acetonitrile medium.     

Iodimetric determination of carbon disulphide study of the effect of pH

The effects of pH and time on the error (due to decomposition of xanthate) involved in the iodimetric determination of carbon disulphide have been studied. A pH range of 5.4 to 5.8 (acetatebuffered) is recommended, Carbon disulphide varying in amount from 0.0060 to 0.3240 g can be determined with an error of ± 1.0%.     

Differential determination of tellurium(IV) and tellurium(VI) with sodium diethyldithiocarbamate, ammonium pyrrolidinedithiocarbamate and dithizone by atomic-absorption spectrophotometry with a carbon-tube atomizer

The extraction behaviour of tellurium(IV) and tellurium(VI) with sodium diethyldithiocarbamate, ammonium pyrrolidinedithiocarbamate and dithizone in organic solvents has been investigated by means of flameless atomic-absorption spectrophotometry with a carbon-tube atomizer. The selective extraction of tellurium(IV) and differential determination of tellurium(IV) and tellurium(VI) have been developed. With sodium diethyldithiocarbamate and carbon tetrachloride, when the aqueous phase/organic solvent volume-ratio is 5 and the injection volume in the carbon tube is 20 microl, the sensitivity for tellurium is 0.3 ng/ml for 1% absorption. The relative standard deviations are ca. 2%. The proposed methods have been applied satisfactorily to determination of tellurium(IV) and tellurium(VI) in various types of water.     

Radiochemical determination of traces of arsenic(III) and antimony(III)

Very simple and rapid radiochemical procedures for the determination of traces of arsenic(III) (up to 0.1 μg) and antimony(III) (up to 0.01 μg) have been developed. The method is based on the isotope exchange between labelled metal diethyldithiocarbamate in carbon tetrachloride and an aqueous sample containing the metal to be determined. The selectivity of the method is rather high; in the presence of thiourea most common metals do not interfere with the determination.     

A Radiochemical Method for Selective Determination of Traces of Lead

Abstract

A very simple and rapid radiochemical method for the determination of 0.01–1 meg of lead has been developed. It consists of adding carrier-free ²¹²Pb to the analysed sample, followed by shaking with a standard lead diethyldithiocarbamate solution in carbon tetrachloride. The amount of non-active lead in the sample is determined from activities of the organic and aqueous phases. A 10-fold excess of bismuth and more than 50–100-fold excess of other metals extractable as diethyldithiocarbamates do not interfere in the determination.