Comparison of Usefulness of Four Chelating Agents (EDTA, NTA, ODA and IDA) for the Chromatographic Separation of Micro and Macro Amounts of Rare Earth Elements.

Literature on the use of four chelating agents namely: ethylenediaminetetraacetic acid, nitrilotriacetic acid, diglycolic acid and iminodiacetic acid for the chromatographic separation of micro and macro amounts of rare earth elements was critically reviewed and supplemented with some new unpublished data from our Laboratory. Advantages and disadvantages of ion exchange chromatography both in cation and anion mode as well as ion interaction chromatography techniques, which were used for rare earth elements separation, are discussed. The usefulness of some of the chromatographic systems for micro-macro separations was discussed and demonstrated. The importance of resilience of the separation method to column overloading in some analytical and larger scale separations was emphasized. The methods described in this article might suit well for recovering of individual lanthanides and yttrium from e-waste and other industrial wastes which were fast accumulating in recent years.

Rare earth elements in fine fraction (<20 µm) of the Vistula River sediments.

Present studies facilitated testing the hypothesis that sediment fraction <20 µm contains different amounts of REEs. The potentially bioavailable rare earth elements (REEs) were determined in the following fractions of the surface sediments of the Vistula River: <5 µm, 5-10 µm, 10-20 µm, and total <20 µm. The attempt was made to fractionate the sediment by self-adjustable split-flow transport-thin fractionation channel operating in the full depletion mode (SPLITT-FFD-SA), which is a new concept and so far unused method for such purposes. All three fractions were separated in the expected particle size ranges. The collected fractions were analyzed with the laser diffraction particle size analyzer and the inductively coupled plasma - mass spectrometer (ICP-MS) to determine the size and the elemental composition. ∑REEs in the Vistula sediments declined from 123.41, through 112.59 to 95.22 mg kg-1 in fractions: 10-20 µm, 5-10 µm, <5 µm, respectively. Eleven, out of sixteen REEs, showed statistically significant declining trend in REEs content, with decreasing particle sizes of sediment fractions. Particularly exceptional was Er, whose content in <5 µm fraction was by 12-20% higher than in larger size fractions. Rare earth elements of the Vistula sediments are considerably enriched in the light rare earth elements (LREEs) relative to the heavy rare earth elements (HREEs), with the LREEs/HREEs ratio declining from 4.01 (10-20 µm) to 3.599 (<5 µm). The sequence of mass weighted REEs content in <20 µm size fraction was as follows: Ce > La > Nd > Y > Sc > Pr > Sm > Gd > Dy > Er > Yb > Eu > Tb > Ho > Tm > Lu.

A comparison study on the use of Dowex 1 and TEVA-resin in determination of 99Tc in environmental and nuclear coolant samples in a SIA system with ICP-MS detection.

This work refers to a comparative study of sorbents widely used in determinations of 99Tc such as TEVA resin and Dowex 1. Despite having a similar functional group of quaternary amines, both materials represent different chromatographic methods-extraction (TEVA resin) and anion exchange (Dowex 1)-which provides a diverse range of their properties significant in determination of 99Tc in flow conditions. The comparative tests, carried out in a SIA-LOV (Sequential Injection Analysis-Lab-on-Valve) system combined with mass spectrometric (ICP-MS) detection, considered several factors that are crucial from the standpoint of resin´s utility such as sorption capacity, durability, or selectivity, critical in 99Tc separation from interferences. The developed and optimized analytical procedure based on the application of the TEVA resin provided determinations of 99Tc at minimum detectable limit (MDL) 6.00 mBq L-1 in 50 min and has been successfully employed in analyses of samples from nuclear industrial and research units (reactor coolant and sewage) as well as from the river surrounding the nuclear reactor. The method proved to be sufficient for routine analysis of water samples in accordance with EPA standards. The reliability of the method was confirmed in the analysis of the BH standard provided by the NPL for inter-laboratory proficiency tests. The 99Tc recovery for all real samples was evaluated as 80-100%.

Automation of sample processing for ICP-MS determination of 90Sr radionuclide at ppq level for nuclear technology and environmental purposes.

90Sr is a widely determined radionuclide for environmental purposes, nuclear waste control, and can be also monitored in coolants in nuclear reactor plants. In the developed method, the ICP-MS detection was employed together with sample processing in sequential injection analysis (SIA) setup, equipped with a lab-on-valve with mechanized renewal of sorbent bed for solid-phase extraction. The optimized conditions of determination included preconcentration of 90Sr on cation-exchange column and removal of different type of interferences using extraction Sr-resin. The limit of detection of the developed procedure depends essentially on the configuration of the employed ICP-MS spectrometer and on the available volume of the sample to be analyzed. For 1L initial sample volume, the method detection limit (MDL) value was evaluated as 2.9ppq (14.5BqL-1). The developed method was applied to analyze spiked river water samples, water reference materials, and also simulated and real samples of the nuclear reactor coolant.

Development of potential candidate reference materials for drugs in bottom sediment, cod and herring tissues.

Regular use of a reference material and participation in a proficiency testing program can improve the reliability of analytical data. This paper presents the preparation of candidate reference materials for the drugs metoprolol, propranolol, carbamazepine, naproxen, and acenocoumarol in freshwater bottom sediment and cod and herring tissues. These reference materials are not available commercially. Drugs (between 7 ng/g and 32 ng/g) were added to the samples, and the spiked samples were freeze-dried, pulverized, sieved, homogenized, bottled, and sterilized by γ-irradiation to prepare the candidate materials. Procedures for extraction and liquid chromatography coupled with tandem mass spectrometry were developed to determine the drugs of interest in the studied material. Each target drug was quantified using two analytical procedures, and the results obtained from these two procedures were in good agreement with each other. Stability and homogeneity assessments were performed, and the relative uncertainties due to instability (for an expiration date of 12 months) and inhomogeneity were 10-25% and 4.0-6.8%, respectively. These procedures will be useful in the future production of reference materials.

Inductively coupled plasma mass spectrometry in comparison with neutron activation and ion chromatography with UV/VIS detection for the determination of lanthanides in plant materials.

Analytical performance of inductively coupled plasma mass spectrometry (ICP-MS) for determination of lanthanides in plant materials was investigated and compared with neutron activation analysis (NAA) as well as ion chromatography (IC) with UV-VIS detection. Two sample preparation protocols were tested: (i) microwave assisted digestion by concentrated nitric acid; (ii) microwave digestion involving silica and fluoride removal, followed by the selective and quantitative lanthanides group separation from the plant matrix. Several Certified Reference Materials (CRM) of plant origin were used for the evaluation of the accuracy of the applied analytical procedures. The consistency of results, obtained by various methods, enabled to establish the tentative recommended values (TRV) for several missing elements in one of CRMs. The ICP-MS, due to its very high sensitivity, has the potential to contribute to this aim. The discrepancy of the results obtained by various methods was discussed in a view of possible matrix effects related to the composition of investigated materials.

Two new reference materials based on tobacco leaves: certification for over a dozen of toxic and essential elements.

The preparation, certification, and characterization of two new biological certified reference materials for inorganic trace analysis have been presented. They are based on two different varieties of tobacco leaves, namely, Oriental Basma Tobacco Leaves (INCT-OBTL-5), grown in Greece, and Polish Virginia Tobacco Leaves (INCT-PVTL-6), grown in Poland. Certification of the materials was based on the statistical evaluation of results obtained in a worldwide interlaboratory comparison, in which 87 laboratories from 18 countries participated, providing 2568 laboratory averages on nearly 80 elements. It was possible to establish the certified values of concentration for many elements in the new materials, that is, 37 in INCT-OBTL-5 and 36 in INCT-PVTL-6, including several toxic ones like As, Cd, Hg, Pb, and so forth. The share and the role of instrumental analytical techniques used in the process of certification of the new CRMs are discussed.

Comparison of performance of INAA, RNAA and ion chromatography for the determination of individual lanthanides.

Lanthanides represent an interesting group of elements which are steadily gaining importance in science and in industry. Literature data suggest that they may have a role in regulating cellular processes and also in agriculture enhancing plant growth. Only few instrumental methods like NAA, ICP-OES and ICP-MS have potential for the determination of low levels of all lanthanides, but in practice they often have to be combined with suitable separation/preconcentration methods to achieve maximum number of elements being determined and to assure good accuracy and precision. In this work an attempt has been made to compare the performance of both variants of NAA: purely instrumental activation analysis (INAA) and radiochemical mode (RNAA) with pre- and post-irradiation group separation for the determination of individual lanthanides with the special emphasis on rarely determined elements (Gd, Ho, Er, Tm, Lu). This has been done by the analysis of two reference materials with different matrices viz. biological (CTA-OTL-1) and mineral (CTA-FFA-1). The results are compared with those obtained by ion chromatography (IC) employing the same lanthanide group preseparation scheme as in the case of RNAA.

RNAA in metrology: A highly accurate (definitive) method.

The idea of highly accurate (definitive) methods by radiochemical neutron activation analysis (RNAA) is presented and illustrated with several examples of methods worked out in this Laboratory over the past several years. Definitive methods by RNAA are constructed by combining reactor neutron activation with very selective and quantitative post-irradiation separation of the indicator radionuclide by column chromatography followed by gamma-ray spectrometric measurement. All conditions for the determination of the individual element are optimized and uncertainties associated with every step of the analytical procedure are minimized. Even after the method has been thoroughly elaborated and validated through the analysis of appropriate certified reference materials (CRMs), the results obtained in each series of measurements are acknowledged as obtained by definitive method only when a series of previously formulated criteria is simultaneously fulfilled. The examples of definitive methods for the determination of cadmium, cobalt and molybdenum, respectively, in biological materials are presented. Each of these methods has detection limit of the order of ng g(-1) or better, and yields accurate and precise results. The expanded standard uncertainty is of the order of 2.6% for the case of single-element determination (Co) and 3.4-5.2% for the less favourable case (Mo) where there is necessity for simultaneous determination of uranium to correct for interference due to fission reaction. Definitive methods by RNAA may constitute an option or alternative with respect to ID-MS as methods of "guaranteed accuracy" being also a perspective solution in the case of monoisotopic elements, for which ID-MS cannot be used.