A critical review of the volumetric methods for the platinum metals

The published methods for the volumetric determination of the six platinum metals have been appraised. The lack of generally applicable and accurate methods is emphasized. No volumetric method has been recorded for the direct application to solutions of platinum metals, ores, concentrates or natural alloys, and only a few for determinations in synthetic alloys such as fire assay beads. Volumetric methods for the platinum metals are characterized by the absence of data concerning methods of dissolution.     

High frequency titrations involving chelation with ethylenediaminetetraacetic acid: Complexation with rare earths

High frequency titrations have been utilized in studying the chelation of rare earth metals with ethylenediaminetetraacetic acid. The use of high frequency titrations for the determination of rare earth metals has also been studied. A procedure is proposed based on direct titrations with disodium ethylenediaminetetraacetate in buffered solutions. Excellent end-points are obtained and the method is accurate in the absence of other metals that might react with the titrant.     

Length-of-stain indicator tubes for the determination of metals in water and solutions

 Indicator tubes have been proposed for the determination of heavy metals in solutions. Preparation procedures for indicator powders based on noncovalent modifications of reversed-phased silica gel sorbents by analytical reagents have been developed. The effects of pH of the sample, the capacity of the sorbent on the reagent, the flow rate, and the diameter of an indicator tube on the length of the colored zone have been studied. Procedures for the determination of Co(II), Fe(II, III), Cu(II), Cd, and the total content of heavy metals in water and solutions have been elaborated. The procedures have been used to analyze natural and waste waters, soil extracts, and industrial solutions. Received: 11 October 1995 / Revised: 7 June 1996 / Accepted: 12 July 1996     

Individual catalytic determination of iridium and rhodium using the oxidation of sulfarsazene by potassium periodate as an indicator reaction in a flow-injection system

A catalytic method has been developed for the individual determination of trace iridium and rhodium using the oxidation of sulfarsazene by potassium periodate as an indicator reaction in a flow-injection system. The analytical range is from 0.10 to 2.0 μg/mL iridium and from 0.0010 to 0.027 μg/mL rhodium. The detection limits are 0.0074 μg/mL iridium and 0.00095 μg/mL rhodium; the determination error does not exceed RSD = 4% in model solutions. The method is selective in the presence of the majority of colored and platinum-group metals. The accuracy of the results has been confirmed by the standard addition method.     

Simultaneous Determination of Microgram Amounts of Platinum and Palladium in Presence of Base Metals by Isolation on Anion Exchange Resin-Loaded Paper and X-Ray Spectrometry

Abstract

A procedure for simultaneous determination of microgram amounts of platinum and palladium in solutions of base metals is described. The two metals are isolated on an anion exchange resin-loaded paper disk and determined by X-ray spectrometry. The method is applied to the determination of platinum and palladium in nickel matte.     

FIA-FAAS system including on-line solid phase extraction for the determination of palladium, platinum and rhodium in alloys and ores

A number of aliphatic mono- and triamines have been investigated as potential reagents for solid phase extraction of Rh, Pd and Pt. Platinum group metals are recovered from hydrochloric acid solutions as ionic associates of their chloride complexes with protonated amines. The recovery of metals depends both on hydrophobic properties of amine and sorbent and on sorption behaviour of amine itself. For on-line solid phase extraction of platinum group metals 4-(n-octyl)diethylenetriamine and hyper cross-linked polystyrene sorbent SSPS have been applied. Quantitative recovery of rhodium and platinum in the form of their hexachloride complexes was achieved under non-equilibrium conditions of on-line dilution. Metals recovered are quantitatively eluted with 1 M hydrochloric acid solution in ethanol. A new FIA-FAAS method for the determination of Rh, Pd and Pt in solutions based on the decomposition of ores and alloys has been proposed. The RSD values are 0.03-0.08 at 50-ppb concentration level. The detection limits are 3-8 ppb for 1 min of preconcentration. The accuracy of the procedure was verified by the analysis of standard reference materials of sulfide ores and alloys.     

Iminodiacetic acid/ethylcellulose as a chelating ion exchanger: Part 2. Determination of trace metals by inductively-coupled plasma atomic emission spectrometry

A chelate-forming cellulose, iminodiacetic acid/ethylcellulose (IDAEC), is applied to the collection of metals from ammonium citrate and acetate solutions. A method is devised for the i.c.p./a.e.s. determination of metal contaminants in magnesium by separation and preconcentration of the metals with IDAEC.     

Radioactive substoichiometric isotope-dilution procedure for the determination of rare earth metals

A theory is developed which describes the equilibrium conditions when solutions containing trace metals and substoichiometric amounts of EDTA are extracted with thenoyltrifluoroacetone. Experimental evidence is given to support the theory. A method for the determination of microgram quantities of rare earth metal is outlined as an application.     

Determination of cadmium by differentialn pulse anodic-stripping voltammetry after salting-out extraction into acetonitrile

A selective and specific method is presented for anodic-stripping voltammetric determination of cadmium after extraction with 0.1Mtetrabutylammonium iodide solution in acetonitrile from aqueous ammonium sulphate solutions. The detection limit of this method is 0.2 ng ml (in the acetonitrile extract). Interference from matrices or large amounts of elements reduced at more positive potentials can be eliminated by prior extraction. The method has been applied to trace analysis for cadmium in zinc, lead and indium metals, and some inorganic salts.     

A study of the chemical forms or species of manganese found in coal fly ash and soil

The chemical speciation of manganese of environmental and toxicological interest was undertaken in coal fly ash and soil. Hard coal used in combustion creates considerable quantities of waste ash. The greatest quantities of industrial ashes are stored in the form of waste-heaps, which create a serious problem as the source of inorganic pollution. It is necessary to identify physical and chemical properties of ash, especially when analyzing the pollution of soil by trace metals, which are potentially mobile in environment. In this work, a new analytical method has been developed and used successfully for identification and determination of chemical forms of manganese in coal fly ash and soil. The basic chemical forms of metals contained in the environmental samples (fly ash and soil) can be described by using sequential extraction method. To identify Mn ions, the UV-VIS spectrophotometric method was used by means of comparative analysis of spectrophotometric spectra of appropriate Mn ions in the standard solutions and solutions obtained after extraction. The concentration of manganese in all solutions was determined by the Flame Atomic Absorption method. The experimental approach and analytical method developed in this study appear adequate for this purpose and can therefore be used for similar research.     

Voltammetric methods for the determination of heavy metals in domestic waste and compost produced from it

Methods of sampling an preparation of waste and compost samples for analysis are described. A voltammetric method has been used for the determination of the contents of toxic heavy metals (one of the most important criterion for compost quality evaluation) in domestic waste and in compost produced from it. A novel method was proposed for the UV mineralisation of water extracts obtained during leaching of waste and compost samples. Copper, lead, zinc and cadmium were determined in wet-digested samples of domestic waste, compost and its extracts by anodic stripping voltammetry. Nickel and cobalt were determined by adsorption voltammetry. The determination of five metals in one sample over a wide range of concentrations and the low cost of the apparatus used are the main advantages of the analytical method described. This has been shown by the determination of the metals in fractions of domestic waste, in compost produced of that waste and in compost mixed with sewage sludge. Special attention has been paid to investigations of the mobilisation of metals from waste and compost during the leaching test.     

Determination of trace metallic impurities in high-purity quartz by ion chromatography

A method has been developed for the determination of relevant trace impurities (alkali, alkaline and transition metals) in high purity quartz by ion-chromatography. In situ reagent (HF) purification and simultaneous sample dissolution was achieved in a multichannel vapour phase digestion assembly. Twenty-one samples can be digested at a time in this vapour phase system. Significant decrease in the process blank levels for all the analytes was observed. Drastic reduction (250 times) of NH4+ blank was achieved in the described vapour phase digestion, which enables the determination of trace concentration of sodium in high purity quartz. After volatilisation of the matrix and unreacted HF, the clear water leached solutions were injected into an ion-chromatograph equipped with conductivity detector for the determination of alkali and alkaline earth metals. In the case of transition metals, the trace residues were leached with 10 mM HCl and after separation on a mixed bed analytical column (IonPac CS5) were detected by spectrophotometry after post column derivatisation using 4-(2-pyridylazo)resorcinol (PAR). The accuracy of the result was checked by their comparison with those obtained by independent methods like inductively coupled plasma (ICP) MS and ICP atomic emission spectrometry. The achievable detection limits are between 0.4 ng/g (Li) and 22 ng/g (Mn). The application of the method to the determination of the above trace metals in two high-purity-grade quartz samples is demonstrated.     

Direct determination of metals in milligram masses and microlitre volumes by direct-current argon-plasma emission spectrometry with sample introduction by electrothermal vaporization

The development of an electrothermal vaporization and direct-current argon-plasma emission spectrometric system which allowed the determination of metals in microlitre volumes and milligram masses is described. For the five metals investigated, the concentration detection limits were comparable to those for conventional pneumatic nebulization of solutions, and the mass detection limits were superior. The use of an ashing stage was found to reduce enhancement by sodium in the determination of copper and manganese by the plasma method. The system was shown to give accurate results for complex biological, nutritional, water and geological samples.     

Sample preparation procedure for the determination of sulphur and trace metals in oil products by the ICP with a minitorch using emulsions

A quick sample preparation method was used for the determination of sulphur and trace metals in oil and oily products by the ICP with a minitorch. Stable aqueous emulsions of oils and oil products were made by using two kinds of emulsifiers (one with low sulphur content, the other sulfonated). Aqueous standard solutions can be used for the preparation of calibration solutions. The contents of S, Al, Cr, Cu, Fe, Mg, Ni and Pb in aqueous emulsions were determined and the results were in good agreement with the composition of oil standard solutions used for control analysis procedure.     

Determination of trace metals in estuarine sediments by graphite-furnace atomic absorption spectrometry

A simple and rapid acid digestion method for the decomposition of estuarine sediments is described. Quantitative recovery of Cd, Pb, Cu, Ni, Co, Be and Co is demonstrated. Sensitive, precise and accurate determination of these trace metals by graphite-furnace atomic absorption spectrometry in combination with the L'vov Platform provides an interference-free technique that permits calibration with simple aqueous solutions of metal standards. The accuracy of the method has been confirmed by analysis of two marine sediment reference materials, MESS-1 and BCSS-1.     

A critical review of neutron activation and tracer methods for the determination of the noble metals

Neutron activation methods for the seven noble metals are critically reviewed up to December, 1965. The methods deal with the determination of trace impurities in each noble metal as well as traces of noble metals in media such as organic material, fission product and other solutions, ores, alloys, minerals, silica and base metals. The need for confirmatory evidence in the case of such complex materials as ores is emphasized.     

Estimation of metal impurities in high-purity nitric acids used for metal analysis by inductively coupled plasma-mass spectrometry.

A simple method to estimate the amounts of ultra-trace metal impurities in nitric acid reagents has been developed. The determination of sixty-four metals in nitric acid was accomplished by direct measurements of 0.1 M nitric acids accurately diluted with ultrapure water by ICP-MS. Though accurate metal concentration could not be obtained for all of the elements, we could effectively evaluate the nitric acid quality by comparing the ion counts of the samples, ultrapure water and standard metal solutions for a calibration prepared with Ultrapur nitric acid.     

Determination of Some Transition Metals by Atomic Absorption Spectroscopy after Extraction with Pyridine-2-aldehyde-2-quinolylhydrazone

The extraction of pyridine-2-aldehyde-2-quinolylhydrazone chelates of cadmium, cobalt, copper, nickel, and zinc into isoamyl alcohol (IAOL) and methylisobutyl ketone (MIBK) has been investigated as a basis for the determination of these metals. Below pH 6 the extraction is enhanced by the addition of perchlorate, suggesting that charged complexes are being extracted by ion-pair formation. Sensitivities (1% absorption) are reported for IAOL and MIBK solutions of the metals sprayed into an air-acetylene flame. A procedure for the determination of the above metals by atomic absorption spectroscopy after extraction is given. The procedure is applied to the analysis of tap water for cadmium, copper, and zinc.     

Matrix separation of palladium and iridium by the cellulose anion exchanger Cellex T and the subsequent determination of palladium at theμg/g-level

The preconcentration and separation of palladium and iridium from base metals is studied with cellulose (Cellex T) and styrene-divinylbenzene (Varion AT 400) anion exchangers. In spite of lower capacity of Cellex T to chloride complexes of Pd and Ir, it allowed to get a higher preconcentration factor. Yields of 92–99% are achieved for Pd and 96–97% for Ir from the solutions containing great excess of base and heavy metals. Graphite furnace atomic absorption spectrometry is used for the final measurements. The procedure has been applied to the determination of palladium in natural samples.     

Spectrochemical analysis of hard metals by a rotating disc technique: effect of impregnation and complexing agents

A spectrographic method has been developed for the simultaneous determination of the constituents W, Co, Ti, Ta and Nb and contaminants Fe, Ni, Or, Mn, Mg and Ca in hard metals. The samples were dissolved in hydrofluoric acid and nitric acid and the solutions stabilized with citric acid. Graphite discs were waterproofed in order to ensure control of the introduction of solution into the source. For the five types of hard metal samples studied no interelement effect was observed. Titanium has also been determined by means of a double-beam optical spectrometer.