ABSTRACT
The reversible sorption preconcentration of noble metals (NMs) using different schemes "sorbent-reagent-eluent" was investigated. The extraction of Au, Pd, Pt, Ir, Rh and Ru chlorocomplexes from hydrochloric acid solutions on hyper-crosslinked polysterene MN-200 in the form of ion associates with tributylamine (TBA) and 4-(n-octyl)diethylenetriamine (ODETA) was investigated. It was found that Pd, Pt and Au were quantitatively and reversibly extracted using TBA on hyper-crosslinked polysterene; the appropriate eluent for desorption was 1M solution of HCl in ethanol. Ir, Rh and Ru under these conditions were not sorbed quantitatively. It was found that sorbent hydrophobicity is not the main characteristic that defines the efficiency of sorption of a particular NM ion associate. Different efficiencies of hyper-crosslinked polysterene MN-200 for sorption of square-planar chlorcomplexes of Pt, Pd and Au and octahedral complexes of Ir, Rh and Ru were found. For the first time, the sorbents with their own N-atoms - StrataX and StrataX-AW - were used for the sorption of Ir, Rh and Ru. Using these sorbents, the sorption of Ir was increased up to 95%, and the sorption of Ru and Rh was increased to about 40%. We can explain these results by nonspecific interaction of chlorcomplexes of Ir, Rh and Ru with ethylenediamine groups of the sorbent. Weak bases with large anions may be applied for desorption of Ir, Rh and Ru. Two schemes of dynamic sorption preconcentration of NMs from hydrochloric acid solutions were proposed - hyper-crosslinked polysterene MN-200 for the determination of Au, Pd, Pt, and StrataX-AW for Ir, Rh and Ru.
ABSTRACT
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.
ABSTRACT
Different methods of rock sample digestion for final analysis by ICP-MS technique are investigated. It is shown that only basic rocks can be quantitatively digested in a microwave (MW) field with the mixture of HF and HNO(3) acids at 210°C for 60 min. The addition of HCl and H(3)BO(3) provides complete digestion of andesites and some types of granites. Even at maximal temperature in the used MW oven of 210°C syenites, granodiorites and albitized granites are not digested. These types of rocks are not digested in a closed Teflon autoclave for 16 h and can be digested only by fusion with lithium metaborate. The reason for such behavior is discussed. To avoid problems with the introduction of heavily acidic solutions after fusion in ICP the solutions were diluted. To compensate the loss of sensitivity due to the dilution step the REEs (Rare Earth Elements) pre-concentration using aminocarboxylic Pol-DETATA (diethyltriaminetetraacetate) sorbent was tested. The developed scheme is validated by the analysis of a wide range of reference rock materials.