A rapid iodometric method for the determination of copper and zinc

A method has been described for the iodometric simultaneous determination of zinc and copper. Copper is determined in the presence of sufficient KCNS and a small amount of KI. This is followed by the titration of the iodine equivalent to the zinc, which is liberated by the addition of potassium ferricyanide solution.Interference is eliminated completely by keeping the solution neutral or just acid with phosphoric acid.Within the range under investgation, results are obtained which are accurate to ± 0.7%.     

A rapid multidimensional liquid-gas chromatography method for the analysis of mineral oil saturated hydrocarbons in vegetable oils

The present paper describes an investigation directed toward the development of a rapid heart-cutting LC-GC method for the analysis of mineral oil saturated hydrocarbons contained in vegetable oils. The automated LC-GC experiments were carried out by using a system equipped with a syringe-type interface, capable of both heart-cutting and comprehensive (LC × GC) two-dimensional analysis. The first dimension separation was achieved on a 100 mm × 3 mm ID × 5 μm d(p) silica column, operated under isocratic conditions (hexane). A single 30-s cut, corresponding to a 175 μL volume, was transferred to a programmed temperature vaporizer. After the large volume injection, the target analytes were separated in a rapid manner (~9 min) using a 15 m × 0.1mm ID × 0.1 μm micro-bore GC capillary. The overall LC-GC run time enables the analysis of ca. 4 samples/hour. Quantification was performed by using external calibration, in the 1-200 mg/kg range. The method was validated in terms of linearity, precision, limits of detection and quantification, and accuracy. A series of commercial samples were subjected to analysis. Various degrees of contamination were found in all samples, in the 7.6-180.6 mg/kg range.     

A rapid spectrophotometric method for determination of piperazine

A spectrophotometric method has been developed for the determination of piperazine and its salts (citrate, phosphate, and tartrate) without prior separation, based on the interaction of piperazine or any of its salts with phenothiazine and N-bromosuccinimide in aqueous methanol. The products exhibit absorption maxima at 448, 595 and 645 nm. Measurements are made at 595 nm. Beer's law is obeyed in the concentration range 0.5-5 mug/ml for piperazine salts and 0.5-3 mug/ml for piperazine hexahydrate. The method is rapid, simple and successful for analysis of some pharmaceutical preparations.     

A novel infrared spectrophotometric method for the rapid determination of petroleum hydrocarbons, and animal and vegetable oils in water

To determine the concentrations of total oils,petroleum hydrocarbons,and animal and vegetable oils in water,the conventional analytical methods involve two scans as well as a step of magnesium silicate adsorption to remove the animal and vegetable oils in water samples.In this study,a novel analytical method was developed to determine the above oils in wastewater samples through just one scan—the concentration of animal and vegetable oils,and that of total oils were determined by measuring the absorbance of the >C=O bond in the peak area between 1750 cm and 1735 cm^-1,and of the C-H bond at 2930 cm^-1,2960 cm,and 3030 cm^-1,respectively.The concentration of petroleum hydrocarbons was then calculated by subtracting the concentration of animal and vegetable oils from that of total oils.Compared with the well-known analytical method GB/T 16488-1996,the novel approach displayed similar accuracy in the quantitative determination of oils in wastewater samples,but significantly reduced material cost and operation time.     

A rapid solid sampling method for determination of nickel and copper along human hair by ETAAS

A procedure for copper and nickel determination in scalp hair by solid sampling electrothermal atomic absorption spectrometric method was described. The hair samples (0.02 to 0.4 mg) were inserted directly on the platforms of solid sampling autosampler. The effects of pyrolysis temperature, atomization temperature, the amount of sample as well as addition of a modifier (Pd/Mg) and/or auxiliary digesting agents (hydrogen peroxide and nitric acid) and/or a surfactant (Triton X-100) on the determination of copper and nickel by solid sampling atomic absorption spectrometry were investigated. After optimization of parameters, the average recoveries of copper in two different certified reference hair samples were 105.7 and 97.6%. The recoveries of nickel in the both certified reference hair samples were in 95.2 and 96.4%. The limits of detection (3σ, N = 10) for copper and nickel were 22 ng/g and 35 ng/g, respectively. Heterogenous distribution of analyte in microscale for segmental analysis could be determined which is important to know that analyte quantity and time of poisoning of a person was exposed. For this purpose, 0.5 cm of pieces were cut along one or a few close strands and analyzed by solid sampling. This process could not be performed by wet-digestion method because 50 mg of sample is needed each time. Finally, the method was applied for the determination of copper and nickel concentrations in the hairs of different persons.     

A rapid method for the determination of radiostrontium in river water

A rapid analytical method, applicable for the selective separation and determination of⁹⁰Sr and⁸⁹Sr in river water, is described. Strontium is extracted from the water sample at pH 10.5 by TTA/TOPO in cyclohexane in the presence of Tiron as masking agent for interfering ß-emitters. Radiostrontium is measured by liquid scintillation after back-extraction into 1N nitric acid. The distribution coefficient of strontium is over 400 and the separation factors from other radionuclides are higher than 5.0×10³.     

A rapid method for the determination of organic carbon in soil

TIURIN'S method for the determination of organic carbon in soil is modified to give results practically identical with those of the dry combustion method. The standard deviation of a single determination is only 12%. By using 50 mg of soil and 10 ml of 0.2 N dichromate solution, soils with a carbon, content up to 12% can bo analysed. The method is suitable for all soils except those containing much chloride or reducing substances other than organic carbon Carbonates do not interfere.     

A rapid method for the determination of the Fusarium mycotoxinbeauvericin in maize

The development of a rapid method for the determination of the Fusarium mycotoxin beauvericin (BEA) in corn and cereals is described. This method allows to prepare at least 5 times more samples simultaneously with similar analytical performance characteristics as previously published analytical methods. Received: 14 May 1998 / Revised: 9 July 1998 / Accepted: 14 July 1998     

A rapid method for the determination of the Fusarium mycotoxinbeauvericin in maize

The development of a rapid method for the determination of the Fusarium mycotoxin beauvericin (BEA) in corn and cereals is described. This method allows to prepare at least 5 times more samples simultaneously with similar analytical performance characteristics as previously published analytical methods.     

A rapid spectrophotometric method for determination of zinc in milk

1-(2',3'-Dihydroxypyridyl-4'-azo)benzene-4-sulphonic acid and the corresponding 5'-chloro-substituted acid are proposed as sensitive reagents for zinc. Cyanide masking and selective demasking of zinc can be used to deal with the interference of many metal ions, cadmium can be masked with semithiocarbazide, and thiosulphate can be used for masking Hg(II), Pd(II) and Os(VIII). The molar absorptivities are about 1.3 x 10(5) 1.mole(-1).cm(-1). The method has been used for determinating zinc in milk.     

A modified micro-dumas method for rapid determination of nitrogen

Summary The Pregl-Dumas method for the estimation of nitrogen has been modified to make it suitable for the rapid performance of a number of analyses in series. The usual combustion tube for carbon and hydrogen determination is used, and the tube filling and procedure are modified.

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Zusammenfassung Die Stickstoffbestimmung nach Pregl-Dumas wurde abgeändert, um die schnelle Durchführung von Serienanalysen zu ermöglichen. Das für Kohlenstoffbestimmungen übliche Verbrennungsrohr wird benutzt. Die Substanz wird in einem Schiffchen eingeführt, auf das eine Rolle aus oxydiertem Kupferdrahtnetz folgt.

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Résumé Modification de la méthode dePregl-Dumas pour permettre le dosage rapide de l'azote en série. Emploi du tube habituellement utilisé pour le microdosage du carbone et de l'hydrogène avec modification du remplissage et de la technique.

     

A rapid routine method for the determination of zinc in wood preservatives

A method is described for the rapid routine determination of zinc in wood preservatives Zinc is separated from interfering chromatc and copper by precipitation as phosphate from neutral solution in the presence of glycine followed by titration with ferrocy anide This method is suitable for zinc concentrations in the range 03–06 rng Zn/ml     

A rapid method for the determination of strontium-90 in powdered milk

A method in which⁹⁰Y the daughter product of⁹⁰Sr decay is extracted by tributyl phosphate (TBP) from ashed powdered milk is described. The⁹⁰Y which is in equilibrium with⁹⁰Sr is back-extracted into the aqueous phase and coprecipitated with milligram amounts of ferric hydroxide. The proposed procedure makes it possible to obtain thin planar sources convenient for low level gas counters. The overall detection efficiency of 45.5% for⁹⁰Y (including chemical recovery of yttrium) was achieved. The detection limit for 200 g powdered milk samples and 10 000 s counting time was 0.065 Bq·kg^–1. The concentration of⁹⁰Sr in three-year old samples (after Chernobyl accident) ranged from 0.81 to 1.31 Bq·kg^–1.