Ion-exchanger colorimetry-VIII Microdetermination of copper in natural waters

A microdetermination method for copper by ion-exchanger colorimetry has been developed. The porphyrin alpha,beta,gamma,gd-tetrakis(4-N-methylpyridyl)porphine was used as the colour reagent. After the complexation at pH 4.5 and 40 degrees , the surplus ligand was converted into the protonated species by addition of sulphuric acid. The complex and the ligand were easily sorbed on the cation-exchange resin, Dowex 50W-X2-H(+) (100-200 mesh). The resin-phase absorbances of the complex species at 424 nm and of the resin background at 510 nm were used for the measurements. There were no interferences by the foreign ions expected to be present in natural waters, at up to 1000 times the concentration of copper. With a 1 -litre sample the detection limit is 0.072 mug/l. It is possible to determine copper at mug/l. or lower levels in natural waters.     

Ion-exchanger colorimetry-VII Microdetermination of iron(II) and iron(III) in natural water

A trace method for iron, based on ion-exchanger colorimetry, has been developed. 1,10-Phenanthroline is used as the colour reagent for iron(II) and citrate as the masking reagent for iron(III). Total iron can be determined after reduction of iron(III) to iron(II) with hydroxylamine. It is possible to determine iron at mug/l.-levels in different oxidation states in natural waters.     

Ion-exchanger colorimetry-IV microdetermination of bismuth in water

Ion-exchanger colorimetry for the microdetermination of bismuth(III) in water samples is described. The yellow bismuth-iodide complexes are specifically sorbed and concentrated on an anion-exchange resin in the sulphate form. The resin-phase absorbances at 492 and 700 nm are measured directly. Bismuth in the ppb-ppm range can be determined without interference, except in presence of a large amount of copper(II), silver(I) and lead(II). The detection limit is 6.4 x 10(-9)M, i.e., 1.3 ppb. The distribution ratio is larger than 10(7). It is, therefore, possible to enhance the sensitivity by increasing the sample volume. The method is useful for the determination of bismuth in natural waters and industrial effluents.     

Ion-exchanger colorimetry-III microdetermination of zinc in water

An ion-exchanger colorimetric method for the determination of zinc(II) with Zincon has been developed. Zinc in a water sample can be determined by sorption onto an anion-exchange resin from 2M chloride solution followed by transformation into a coloured complex with Zincon. With use of a 1-litre sample the sensitivity is 10 times greater than that for conventional colorimetry. Most metals, except cadmium(II), lead(II) and bismuth(III), do not interfere when present in up to 100 times the concentration of zinc. The zinc: Zincon ratio of the complex in the resin phase was found to be 1 : 1 by the molar ratio method.     

Ion-exchanger colorimetry-II microdetermination of chromium in natural waters

Ion-exchanger colorimetry for chromium(VI) with 1,5-diphenylcarbohydrazide has been developed for the determination of chromium at mug/l. concentrations in natural water samples. About 90% of the chromium(VI) in a 1-litre sample solution is concentrated in 200-400 mesh Dowex 50W-X4 resin within half an hour. It is possible to obtain higher sensitivity by employing a larger amount of sample solution. Total chromium can be determined by oxidizing chromium(III) to chromium(VI) with ceric sulphate.     

Ion-exchanger colorimetry-I Micro determination of chromium, iron, copper and cobalt in water

A new sensitive, colorimetric method based on the direct measurement of light-absorption by an ion-exchange resin phase, which has sorbed the sample complex species, has been developed. Determinations ofchromium(VI) with diphenylearbazide, iron(II) with 1,10-phenanthroline, copper with Zincon and cobalt with thiocyanate have more than ten times the sensitivity obtainable with conventional solution colorimetry. The present method can be applied to natural water samples containing very low levels of these metals.     

Microdetermination of dissolved oxygen in water by a rapid spectrophotometric method

A spectrophotometric method utilizing the dye indigo carmine has been applied to the analysis of dissolved oxygen in water samples. Oxygen concentration has been determined by the decrease in absorbance at 410 mμ of reduced indigo carmine solutions oxidized by dissolved oxygen. A simple modification of the sample compartment of a Bausch and Lomb Spectronic 20 or 340 spectrophotometer allows rapid and accurate measurements to be made within 3 min. Dissolved oxygen in the ranges of 0 to 10% and 0 to 100% saturation can be analyzed without many of the interferences inherent in the standard Winkler method.     

Microdetermination of arsenic in water,spectrophotometrically, by arsine-silver diethyldithiocarbamate-morpholine-chloroform system

An improved spectrophotometric method for microdetermination of arsenic in water using arsine-silver diethyldithiocarbamate-morpholine-chloroform system is described. Sensitivity and molar extinction coefficient are 0.0055 μg As/ml and 1.35 × 10⁴ M⁻¹ cm⁻¹ at 510 nm. The color is stable for 3 days. Six other systems are also studied and compared including the silver diethyldithiocarbamate-pyridine system. Interference due to 19 diverse ions has been studied. Antimony interference is removed by excess stannous chloride solution. The method replaces the commonly employed less stable arsine-silver diethyldithiocarbamate-pyridine method.     

Internal electrolysis for the separation of ions: Microdetermination and separation of nickel and cobalt

Summary The application of internal electrolysis with the Pt-Zn electrode assembly has been described for the separation and determination of nickel and, cobalt (in the 1–5 mg range) from each other and from other ions as well as the determinations of bismuth, copper, cadmium, lead, antimony, nickel and cobalt when present in a mixture.

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Zusammenfassung Die Anwendung der internen Elektrolyse mit einer Pt-Zn-Elektrodenanordnung für die Trennung und Bestimmung von Nickel und Kobalt (in der Größenordnung 1 bis 5 mg) nebeneinander und in Gegenwart anderer Ionen wird beschrieben. Desgleichen auch die Bestimmung von Bi, Cu, Cd, Pb, Sb, Ni und Co in einer Mischung.

     

Microdetermination of radiocaesium

Summary A method has been worked out for measurement of¹³⁷Cs in environmental (vegetal or zoological) samples. To the solution obtained from the sample after pre-ignition, ignition and acidic dis-solution, enough KCl is added to saturate it. Hexachloroplatinate(IV) reagent is then added in substoichiometric amount. The caesium hexachloroplatinate precipitate is filtered off, and its mass andgb-activity are measured. From the experimental data the concentration of radioactive¹³⁷Cs can be evaluated. The method is based on the finding that the radioactive yield, corrected for the chemical yield, is constant (88%) and independent of KCl concentration if the precipitation is carried out from solutions of high KCl concentration with a substoichiometric amount of hexachloroplatinic acid.

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Mikrobestimmung von Radiocäsium

Zusammenfassung Für Umweltschutz-Zwecke wurde eine neue Methode für die Messung der¹³⁷Cs-Aktivität in verschiedenen pflanzlichen und tierischen Proben ausgearbeitet. Zur Aschelösung gibt man KCl bis zur Sättigung zu und fällt dann das Cäsium mit einer substöchiometrischen Menge Hexachloroplatinsäure. Nach Filtration wird die Menge des Niederschlages und seinegb-Aktivität gemessen. Daraus kann man die Konzentration des¹³⁷Cs berechnen. Grundlage der Methode ist die Feststellung, daß die Ausbeute an radioaktivem Cäsium korrigiert durch die Ausbeute an inaktiver Substanz aus Lösungen hoher KCl-Konzentration (88%) konstant und von der KC1-Konzentration unabhängig ist.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Microdetermination of Xanthates

Summary A rapid, convenient and accurate method for the determination of xanthates has been developed. N-bromosuccinimide has been used to displace iodine from potassium iodide which in turn oxidizes xanthate to dixanthogen. The p_H 4 is optimum for the determination. The maximum relative standard deviation is 6% in the case of ethyl potassium xanthate when a 0.5 mg sample was taken.

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Zusammenfassung Ein genaues Verfahren zur raschen Bestimmung von Xanthat wurde entwickelt. N-Bromsuccinimid dient zur Freisetzung von Jod aus KJ; Jod oxydiert Xanthat zu Dixanthogen. Das optimale p_H für die Bestimmung ist 4. Die größte relative Standardabweichung ist 6% bei einer Einwaage von 0,5 mg Kaliumäthylxanthat.

     

Microdetermination of Cyanide

Abstract

A volumetric procedure is described for the micro-determination of cyanide. Small amounts of cyanide can be estimated even in presence of chloride if it is present in the electrolytic bath. N-Bromosuccinimide (NBS) is used to quantitatively oxidized cyanide to cyanate. The end point is reached when the rose red color of the bordeaux red is changed to distinct yellow. From 1–6 mg. of cyanide were analyzed with an average relative standard deviation of about 0.66%.     

Determination of nickel in water by chemiluminescence

The acetone chemiluminescence determination of nickel in water was investigated. Optimization data for the determination of Ni2+ and interference data for over 20 species are provided. The limit of detection for Ni2+ by this method is 2.5 ng ml-1, and the linear dynamic range is from 10 ng ml-1 to 1 microgram ml-1. The application of the method to the determination of Ni2+ in river and waste waters is discussed.     

Inorganic complexation of nickel and cobalt in natural waters

The distribution of nickel and cobalt species has been computed, based on the pH-dependent model of Zirino and Yamamoto. The media used in the pH range of 7 to 9 are natural waters like fresh water, sea water and a mixture of them at different compositions, at 25°C temperature and 1 atm pressure. In fresh water, both nickel and cobalt dominate as free cations at lower pH, and as carbonato complexes at higher pH. In sea water, chloro complexes are significant. In mixtures of the two kinds of water, as might be found in a totally mixed estuary, chloro complexes are important, varying slowly with pH. Sea water plays an important role in complexation. The present results are in excellent agreement with experimental data obtained by the resin exchange method.     

Microdetermination of Morphine in Urine

Abstract

A volumetric procedure for the determination of morphine in urine has been developed. The method is convenient, precise and accurate. N-bromosuccinimide has been used as a titrant using bordeaux red as indicator which changes from rose red to yellow at the end point. 1.51 to 9.06 mg morphine is determined from 100 ml of urine and the maximum relative standard deviation is 3% when 1.51 mg morphine is determined.     

Investigation of lead and nickel contaminated natural biofilms

Total reflection X-ray fluorescence spectrometric method was developed for elemental analysis of lead and nickel contaminated natural biofilms grown on polycarbonate substrates. The biofilms were grown in the Lake of Velence for 4 weeks and then in the laboratory in contaminated lake water for other 2 weeks. It was established that the accumulation of these bivalent cations were practically the same and in their presence the accumulation of zinc decreased by approximately 20% while the other elements (Ca, K, Fe, Mn, Sr, Ti, Rb) showed smaller changes within the statistical interval. From biological point of view, these two bivalent cations reduced the abundance of the algae, to a similar extent; however, the total biomass production was significantly hampered only by nickel (14%).     

Surfactant-free synthesis of nickel nanoparticles in near-critical water

Nickel nanoparticles have been produced by combining two well-tested methods: (i) the continuous flow supercritical reactor and (ii) the reduction of a nickel salt with hydrazine. The normal precipitation of a nickel-hydrazine complex, which would complicate pumping and mixing of the precursor, was controlled by the addition of ammonia to the precursor solution, and production of nickel nanoparticles with average sizes from 40 to 60 nm were demonstrated. The method therefore provides some size control and enables the production of nickel nanoparticles without the use of surfactants. The pure nickel nanoparticles can be easily isolated using a magnet.