Preconcentration of trace copper with yeast for river water analysis

A sensitive and selective method has been introduced for the determination of ultra trace amounts of Ru(III) based on its catalytic effects on the oxidation of Brilliant green (BG) by sodium bromate. A flow injection method has been used with spectrophotometric detection. The method is based on measuring the decrease in absorbance of BG at lambda(max)=615 nm. The decrease in absorbance of BG is linear with the concentration range of 0.005-0.500 mug ml(-1) Ru(III). The limit of detection is 0.002 mug ml(-1). The influence of reagent concentration, manifold parameter and potential interference species has been investigated. The method was used for the determination of ruthenium in synthetic samples with satisfactory results.     

Preconcentration techniques for inorganic trace analysis

Summary In inorganic trace analysis, concentration of desired trace elements is frequently required prior to the instrumental determination to lower the detection limits, improve the precision and accuracy of analytical results, and to widen the scope of the determination techniques. This paper surveys the present status and future prospects of preconcentration techniques. Here, emphasis is placed on control of contamination and losses of trace elements, preconcentration from large volumes of aqueous solutions, microscale preconcentration techniques for high-purity solid microsamples, and preconcentration techniques for trace element speciation in natural waters. Continuous-flow coprecipitation-flotation and other techniques which have been developed in the author's laboratory in recent years are given as examples.

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Anreicherungsverfahren für die anorganische Spurenanalyse

Zusammenfassung In der anorganischen Spurenanalyse ist vor der instrumenteilen Bestimmung oft eine Anreicherung der zu bestimmenden Spurenelemente erforderlich. Hierdurch kann man das Nachweisvermögen sowie die Präzision und die Richtigkeit verbessern und den Anwendungsbereich der Methode erweitern. Es werden in der vorliegenden Arbeit Entwicklungsstand und Entwicklungstendenzen bei Anreicherungstechniken behandelt. Probleme betreffend Kontamination, Verluste von Spurenelementen, Anreicherung aus großen Volumina wäßriger Lösungen, Mikromethoden für Anreicherung im Fall von Mikromengen fester Reinststoffe und Anreicherungsverfahren bei Speziesbestimmungen in natürlichen Gewässern werden diskutiert. Als Beispiele werden auch kontinuierliche Mitfällungs- und Flotationsverfahren sowie andere Techniken, die im Laboratorium des Autors ausgearbeitet wurden, behandelt.

     

Preconcentration of trace elements from natural water with palladium precipitation

Palladium salts can be used as a coprecipitation carrier for the preconcentration of trace elements from natural water prior to their measurement by atomic spectrometry (AAS). The palladium is subsequently reduced by the introduction of hydrogen gas into the sample solution. The procedure is applied to the determination of Cu, Pb and Cd in seawater (enrichment factor 50) and synthetic water samples. Operating conditions have been optimized for the analysis of real samples. With the technique established an enrichment factor (500 fold) is feasible in synthetic samples. The recoveries of Cu, Cd and Pb from seawater are 95, 103 and 100%, respectively. This simple and rapid method can be applied in a wide pH-range and with complex matrices.     

Preconcentration techniques for trace analysis via neutron activation

A review is given of the methods that have been proposed for enrichment of trace elements in samples that are to be analysed by neutron-activation methods. The emphasis is on classification of methods, with full illustrations by means of practical examples.     

Preconcentration of trace elements from natural water with palladium precipitation

Palladium salts can be used as a coprecipitation carrier for the preconcentration of trace elements from natural water prior to their measurement by atomic spectrometry (AAS). The palladium is subsequently reduced by the introduction of hydrogen gas into the sample solution. The procedure is applied to the determination of Cu, Pb and Cd in seawater (enrichment factor 50) and synthetic water samples. Operating conditions have been optimized for the analysis of real samples. With the technique established an enrichment factor (500 fold) is feasible in synthetic samples. The recoveries of Cu, Cd and Pb from seawater are 95, 103 and 100%, respectively. This simple and rapid method can be applied in a wide pH-range and with complex matrices.     

Preparation and certification of JAC river water reference material for trace element analysis

 The Japan Society for Analytical Chemistry has recently issued a river water-certified reference material (CRM) for use in the ultratrace analysis of elements in fresh water. The river water CRM consists of a set of two (natural and spiked) 500-ml samples. The natural water is certified for Pb, Cr, As, Cu, Fe, Mn, Zn, B and Al at their sub-μg/l levels, while the spiked water is intended for use in the regulatory analysis of tap water and fresh water. Key words River water · Trace element analysis · Regulatory analysis · Reference materials     

Preconcentration of trace elements for neutron activation analysis using activable tracers

Use of an enriched isotope as an activable tracer is proposed for the preconcentration of trace elements in neutron activation analysis. As a test of this method, contents of cadmium in various biological standard samples were determined by addition of an enriched¹¹⁶Cd tracer in the preconcentration step followed by neutron irradiation and -ray spectrometry. The principle, advantage, and limitations of the method are also discussed.     

Determination of trace amounts of phosphate in river water by flow-injection analysis

A flow-injection analysis system for the determination of trace amounts of phosphate in river water has been developed. The phosphate is reacted with molybdate and Malachite Green in acidic medium to form a green species, the absorbance of which is measured at 650 nm. Phosphorus (as inorganic phosphate) can be determined at the level of several ng ml in water. Analyses can be done at a rate of up to 40 per hour.     

Preconcentration of contaminants in water analysis

Among the environmental areas, in this review attention will be focused on water matrices and both on organic (e.g., pesticides, herbicides, phenols, polycyclic aromatic hydrocarbons), inorganic species and anion pollutants, since these kinds of substances include a wide number of compounds with different physical and chemical properties and different effects on human health. Analytical methods for control of quality of waters are required to be highly specific and possibly highly sensitive for the determination of even low amounts of pollutants. The main problems encountered during the analysis are the separation of matrix components from the pollutants of interest and the achievement of low detection limits. Therefore an overview on different materials and techniques available for sample concentration and/or matrix removal will be provided and discussed according to the chemical characteristics of the pollutant that has to be enriched.     

Preconcentration and voltammetric determination of trace myoglobin at a 6-mercaptopurine modified silver electrode

6-Mercaptopurine(6-MP) is covalently modified onto a silver electrode to construct a chemically modified electrode (CME). It exhibits the capability of selectively complexing myoglobin and can be applied as a selective biosensor for this compound. Myoglobin is accumulated onto the CME at 0.32 V (vs. SCE); after exchanging the medium it is determined by differential pulse stripping voltammetry. A cathodic stripping peak is obtained at 0.15 V (vs. SCE) by scanning the potential from 0.35 to –0.1 V. The peak currents are linearly proportional to the concentration of myoglobin in the range of 0.2 ∼ 4 μg/mL with a relative standard deviation of 7.8%. The detection limit is about 0.1 μg/mL. The mechanism of the complexation is also discussed. Received: 30 January 1997 / Revised: 7 May 1996 / Accepted: 10 May 1996     

Preconcentration and voltammetric determination of trace myoglobin at a 6-mercaptopurine modified silver electrode

6-Mercaptopurine(6-MP) is covalently modified onto a silver electrode to construct a chemically modified electrode (CME). It exhibits the capability of selectively complexing myoglobin and can be applied as a selective biosensor for this compound. Myoglobin is accumulated onto the CME at 0.32 V (vs. SCE); after exchanging the medium it is determined by differential pulse stripping voltammetry. A cathodic stripping peak is obtained at 0.15 V (vs. SCE) by scanning the potential from 0.35 to –0.1 V. The peak currents are linearly proportional to the concentration of myoglobin in the range of 0.2 ～ 4 μg/mL with a relative standard deviation of 7.8%. The detection limit is about 0.1 μg/mL. The mechanism of the complexation is also discussed.     

Preconcentration and instrumental neutron activation analysis of acid rain for trace elements

A combination of instrumental and preconcentration neutron activation analysis (NAA) methods has been developed for multielement determination in acid rain. Concentrations of 24 elements have been measured in the particulate matter of rainwater by the instrumental NAA method which involves 3 irradiation and 4 counting periods. Trace elements in the soluble fraction of rainwater have been preconcentrated using Chelex-100 resin. Various factors that could influence the retention of elements on to the resin have been examined, and reagent and other blanks investigated in detail. Concentrations of 15 elements have been measured by directly irradiating the resins. A graphite furnace atomic absorption spectrometry method has been used for determining Cd and Pb levels in the soluble fraction. Precision and accuracy of the methods have been evaluated, and limits of detection and determination calculated. The methods have been applied to rainwater samples collected from 36 locations across Canada. Enrichment factors, interelement and inter-ion concentration correlation coefficients are discussed     

Preconcentration of trace heavy metals in water by coprecipitation with magnesium oxinate for electrothermal atomic absorption spectrometry

Nanogram quantities of heavy metals in 200 ml of water were quantitatively preconcentrated by coprecipitation with magnesium oxinate at pH 9–9.5. The precipitate was collected on a 1-m Nuclepore membrane filter and then dissolved in 5 ml of 1 mol/l nitric acid. After diluting to 10 ml with water, a 10- or 20-l aliquot of the solution was directly analyzed by electrothermal atomic absorption spectrometry using deuterium background correction. The background absorption due to the collector magnesium oxinate was negligibly small. The optimized coprecipitation technique has been applied to the determination of cobalt, nickel, copper, cadmium and lead at the ppt level in river and seawater. The relative standard deviations were within 10% and the detection limits were 0.025 (for Co), 0.019 (for Ni), 0.006 (for Cu), 0.001 (for Cd) and 0.017 g/l (for Pb). Blanks through the whole procedure were not detectable.     

Preconcentration of trace elements from water samples on a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO2 nanoparticles for determination by ICP-AES

A trace element preconcentration procedure is described utilizing a minicolumn of yeast (Yamadazyma spartinae) immobilized TiO₂ nanoparticles for determination of Cr, Cu, Fe, Mn, Ni and Zn from water samples by inductively coupled plasma atomic emission spectrometry. The elements were quantitatively retained on the column between pH 6 and 8. Elution was made with 5% (v/v) HNO₃ solution. Recoveries ranged from 98 ± 2 (Cr) to 100 ± 4 (Zn) for preconcentration of 50 mL multielement solution (50 μg L⁻¹). The column made up of 100 mg sorbent (yeast immobilized TiO₂ NP) offers a capacity to preconcentrate up to 500 mL of sample solution to achieve an enrichment factor of 250 with 2 mL of 5% (v/v) HNO₃ eluent. The detection limits obtained from preconcentration of 50 mL blank solutions (5%, v/v, HNO₃, n = 11) were 0.17, 0.45, 0.25, 0.15, 0.33 and 0.10 μg L⁻¹ for Cr, Cu, Fe, Mn, Ni and Zn, respectively. Relative standard deviation (RSD) for five replicate analyses was better than 5%. The retention of the elements was not affected from up to 500 μg L⁻¹ Na⁺ and K⁺ (as chlorides), 100 μg L⁻¹ Ca²⁺ (as nitrate) and 50 μg L⁻¹ Mg²⁺ (as sulfate). The method was validated by analysis of freshwater standard reference material (SRM 1643e) and applied to the determination of the elements from tap water and lake water samples.     

Preconcentration of silver as silver xanthate on activated carbon

Silver from aqueous solution was preconcentrated by adsorption on activated carbon as silver xanthate. Factors influencing the adsorption of silver have been studied. Optimum conditions for the preconcentration of silver have been established.     

Preconcentration and determination of trace metals in synthetic sea water by flotation with inert organic collectors

The preconcentration and separation of copper, cadmium, cobalt and nickel 8-quinolinolates in solutions of high salinity including synthetic sea water is studied with phenolphthalein or 2-naphthol as collector and octadecylamine as surfactant. A simplex optimization is applied. Yields > 90% are achieved for Ni, Co and Cd with both collectors, but the copper yield is low. Flame atomic absorption spectrometry is used for the final measurements.     

Preconcentration methods for the analysis of water by x-ray spectrometric techniques

All published procedures for multi-element preconcentration of trace elements, prior to x-ray fluorescence analysis of water, are reviewed and critically evaluated. Most preconcentration methods applied to the determination of single elements in water are also listed.     

Preconcentration of silver from rocks by extraction with bismuth dibenzyldithiocarbamate prior to neutron activation analysis

The method developed for determining trace levels of silver in geological materials involves the extraction of silver with a toluene solution of bismuth dibenzyldithiocarbamate followed by neutron activation of the extract. At pH 2 and in the presence of 0.1M EDTA, silver is quantitatively extracted. Under these conditions only small amounts of copper are coextracted. The detection limits of silver for three different modes of neutron activation analysis: /three cycles with Ge/Li/ detector, one cycle with Ge/Li/ detector and one cycle with NaI/Tl/ detector/ were 12, 20 and 11 ng g^–1, respectively.     

Preconcentration of trace metals in river waters by the application of chelate adsorption on Amberlite XAD-4

Summary The adsorption of metal chelates formed by APDC and oxine on Amberlite XAD-4 was investigated in order to determine the optimal conditions for preconcentration of trace metal ions. The investigated metal ions were Cu, Cd, Mn, Co, Pb, Ni and Fe. The recovery yields were determined by use of flame AAS. The method was applied to river waters with satisfactory results (recovery >95%; relative standard deviation 1–5%).Dedicated to Prof. Dr. B. Schrader on the occasion of his 60th birtday     

Preconcentration of trace elements by aluminium hydroxide

Summary Coprecipitation of traces of cobalt, zinc, chromium, ruthenium and mercury with freshly precipitated aluminium hydroxide has been investigated by a radiotracer method. Investigations were performed over a wide range of pH. The results indicate that traces of cobalt, zinc and chromium could be almost completely coprecipitated between pH 6 and 10. On the other hand coprecipitation yield for ruthenium in this pH range do not exceed 95%, which is believed to be the consequence of the various physicochemical states of ruthenium. The coprecipitation yields for mercury are very low as a consequence of the presence of non-ionized HgCl₂.

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Zusammenfassung Die Mitfällung von Spuren Kobalt, Zink, Chrom, Ruthenium und Quecksilber mit frisch gefälltem Aluminiumhydroxid wurde radiochemisch untersucht. Die dazu nötigen Experimente erstreckten sich über ein weites pH-Gebiet. Die Ergebnisse zeigen, daß Spuren Kobalt, Zink und Chrom zwischen pH 6 und 10 fast vollständig mitgefällt werden konnten. Andrerseits sind die Mitfällungsausbeuten für Ruthenium in diesem pH-Gebiet nicht größer als 95%, was vermutlich die Folge der verschiedenen physikalischchemischen Zustände des Rutheniums ist. Die Mitfällungsausbeuten für Queckilber sind infolge der nur geringen Dissoziation des HgCl₂ sehr gering.