G. I. Tsysin

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.

Determination of low levels of platinum group metals: new solutions

Abstract A new rapid sample preparation scheme for the determination of low levels of platinum metals (PMs) has been proposed. The technique includes, microwave dissolution of samples followed by dynamic sorption preconcentration of the PMs on a polystyrene based sorbent containing diethylenetriamine groups. Non-equilibrium dynamic conditions allowed simultaneously and nearly quantitative recovery of all the PMs in the presence of a 10 6 –10 7 excess of matrix elements. Metals were determined in slurries of concentrates by Zeeman electrothermal atomic absorption spectrometry. A good agreement between the results obtained and the certified values was demonstrated. The relative standard deviation is generally 0.05. Detection limits obtained were 10 −6 –10 −7 %.

X-ray fluorescence determination of As, Bi, Co, Cu, Fe, Ni, Pb, Se, V and Zn in natural water and soil extracts after preconcentration of their pyrrolidinedithiocarbamates on cellulose filters

A simple method for the elements preconcentration on thin-layer paraffin-treated cellulose filters was proposed. It was found that pyrrolydinedithiocarbamates of As(III), Bi, Cd, Co, Cu, Fe(III), Ni, Pb, Se(IV), V(V) and Zn obtained after mixing of sample (3-5 ml min(-1)) and reagent (0.7-1.0 ml min(-1)) streams were quantitatively recovered from 100 ml sample. The sample acidity was adjusted to pH 4.8-5.2 for preconcentration of Cd, Co, Cu, Fe(III), Ni, Pb, V(V) and Zn, and to 2 M HCl for preconcentration of As, Bi and Se. The optimum reagent concentration was found to be 0.1%. The elements were determined on the filters by X-ray fluorescence spectrometry. The detection limits achieved were 0.1-4.0 mug of element on the filter. Relative standard deviation (R.S.D.) was not higher than 0.08 while determining 5-50 mug of elements on filter. Accuracy and precision of the technique proposed were evaluated by the analysis of spiked natural samples.

Shipboard flow injection method for the determination of manganese in sea-water using in-valve preconcentration and catalytic spectrophotometric detection

A flow injection method for the determination of manganese at trace level concentrations in sea-water is proposed. The in-valve ion-exchange microcolumn for preconcentration was directly coupled to the spectrophotometer. The spectrophotometric detection was based on the catalytic effect of MnII on the oxidation of N,N-diethylaniline by potassium periodate in a neutral medium. Variation of the preconcentration time from 10 s to 10 min allowed the determination of manganese in the concentration range 20 µg l–1–10 ng l–1. A sampling frequency of up to 15 h–1 and a relative standard deviation of 5–8% were achieved. The proposed method was successfully applied to the direct shipboard measurement of the manganese content in deep sea-water samples for the purpose of indicating the presence of active hydrothermal vents on the sea floor.

On-line-sorption preconcentration and inductively coupled plasma atomic emission spectrometry determination of rare earth elements

Abstract The system for on-line microcolumn sorption preconcentration and inductively coupled plasma atomic emission spectrometry determination of 14 rare earth elements (REEs) is described. Aminocarboxylic sorbents of different structure are used. Preconcentration of REEs from the 20 ml of sample solution and elution with 210 μl of 1 mol l −1 HCl results in an enrichment factor of 99. The detection limit of REEs is about n × 0.1 μ g l −1 (RSD 3–5%). The possibility of simultaneous REE determination in complicated solutions is demonstrated.

Cellulose fibrous sorbents with conformationally flexible aminocarboxylic groups for preconcentration of metals

New cellulose fibrous sorbents, containing a diethylenetriamine tetraacetate groups, are proposed for the preconcentration of heavy metals. Quantitative extraction of heavy metals from river and sea water is achieved in a wide pH range (3–8) at a high solution flow rate (up to 100–150 volumes of sorbent per minute). Quantitative desorption of metals is achieved with a very small volume of the acid.

Application of linear model of sorption dynamics to the comparison of solid phase extraction systems of phenol

A method based on the linear model of sorption dynamics (LMSD) is applied for the comparison of several solid phase extraction systems used for preconcentration of phenol from water solutions. The method includes the calculation of maximum concentration efficiency for the given values of preconcentration factor and recovery under scope of the model. Original parameters of LMSD were obtained from the experimental data on kinetics of sorption of phenol on different hydrophobic non-polar sorbents including poly(styrene-divinylbenzene) (Amberlite XAD-2, PLPR-S 100), hypercrosslinked polystyrene (Purosorb MN-200), hexadecylsilica (KSK-G C16) and others (Amberlite XAD-4, Amberchrom CG-161). The suitability of LMSD for evaluation of dynamic sorption systems is discussed.

Determination of rare earth elements in rock samples by inductively coupled plasma mass-spectrometry after sorption preconcentration using Pol-DETATA sorbent.

Sorption preconcentration of rare earth elements prior to introduction in inductively coupled plasma mass spectrometry is developed. For the first time Pol-DETATA sorbent was used for REEs preconcentration after digestion of wide classes of rock samples. The developed technique is based on lithium metaborate fusion, preconcentration on Pol-DETATA sorbent, elution with nitric acid and flow-injection sample introduction to the ICP-MS spectrometer. The efficiency of REEs extraction from the resulting solutions in the presence of high amounts of iron is examined. 5-sulfosalicylic acid was used as a masking reagent. Flow-injection introduction of 50 μL of eluate obtained after desorption was used to avoid corrosion of the parts of the ICP-MS instrument due to high acidity of the eluate. The accuracy of the developed technique is checked by the analysis of the certified reference materials of rock samples. The REEs recoveries within 85-100% interval were attained for most REEs in tested reference materials.

Detata-filters for metal preconcentration and multielement determination in natural waters

Abstract New sorption filters containing conformationally flexible aminc-carboxylic groups were proposed for preconcentration of metals. Quantitative recovery of metals was achieved in a dynamic regime at a solution flow rate up to 4 ml.min−1.cm−2 in a pH range 3–8 from solutions with high salt content and in the presence of natural complexing agents. The dynamic capacity of DETATA-filters of the heavy metals was investigated. XRF and ICP-AES methods of heavy metals determination after preconcentration on the filters were developed.

Sorption of palladium on hydrophobic polymers in the presence of alkylamines

Abstract Distribution ratios of palladium(II) between hydrochloric acid solutions and some non-polar sorbents in the presence of various reagents containing amino groups were determined. The sorption of palladium is caused by the formation of hydrophobic ionic associates of PdCl 4 2− anion with protonated amines. The recovery of palladium depends on the hydrophobic properties of ion associates and on the sorption behaviour of the amines themselves. The system involving hyper cross-linked polystyrene SSPS and 4- n -octyldiethylenetriamine was chosen for the on-line preconcentration of palladium. Conditions for the quantitative recovery and desorption of the metal were found. A FIA–FAAS method for the determination of palladium including on-line sorption preconcentration has been developed.