ABSTRACT
Solid sampling-electrothermal vaporisation-inductively coupled plasma-mass spectrometry (SS-ETV-ICP-MS) is an attractive technique for the direct simultaneous determination of trace elements in solid samples and especially in long-term studies (i.e. assessment of the homogeneity of reference materials). However, during these studies a downward drift in the instrument sensitivity has been observed due likely to deposits on the sampling and skimmer cones and on the ion lens of the mass spectrometer. Accordingly, in this paper, several means of correcting and/or suppressing sensitivity drift are proposed and evaluated for the monitoring of Cd, Cu, Hg, Mn, Pb, Sb, Se, Sn, Tl, U and V in different reference materials of inorganic and organic (biological) origin. From that studies, the combination of the use of the argon dimer as internal standard together with a modification in the ETV-ICP connection tube seems to be the best mean of getting stable sensitivity during at least 60 consecutive ETV runs.
ABSTRACT
Radiochemistry has always been and still is a crucial tool in the field of radionuclide determination, both for high and low level works; this holds particularly in the case of alpha and beta emitters. Requests to the analyst are increasingly demanding in terms of performance (detection limit, reliability, accuracy, precision,...), but also of economy (cost, time,...) and of flexibility with respect to sample types. In general, chemical and radiochemical analyses consist of four main steps: sample pre-treatment including pre-concentration, dissolution and/or digestion, separation of analytes from the matrix and from each other, transformation of the separated fraction into a source suited for measurement, determination of the amount or the activity of the analytes. The required combination of sub-procedures is determined by the analytes under investigation, their absolute and relative amounts, the matrix composition and by the performance required. IRMM's Analytical Chemistry Unit started several years ago to develop, adapt and/or validate various radiochemical methods and procedures, and apply these to different measurement tasks. This paper gives an overview on recent and ongoing activities.
ABSTRACT
The first part of comparison study was based on the properties of different sorbents. These included different forms of manganese oxides, and specific organic ion-exchangers: HYPHAN and POLYORGS. In order to provide reproducible samples with moderate presence of possible interferences, spiked tap water was used for this first set of experiments. Results indicate that the sorption of Th, U, Pu and Am varies for different forms of manganese oxides. These variations are attributed to different physico-chemical properties of the oxides. HYPHAN was limited in its sorption to Th and U. The manganese oxide dissolved rapidly and the radiochemical separation procedure was quick and simple using extraction chromatography techniques. The radionuclides in the water samples were determined by ICP-MS and/or alpha spectrometry.
ABSTRACT
A method has been optimized to preconcentrate uranium from waters using the ion exchanger Hyphan. The sample (up to 10 1) is agitated thoroughly with a portion of the ion exchanger for between 40 min and 2 h. The exchanger is filtered off and treated with a small volume (< 100 ml) of either nitric acid (for ICP measurement) or hydrochloric acid (for alpha measurement). The acid is filtered off and measured directly by ICP-AES, or it is brought to pH 2 and saturated with ammonium chloride, then directly electrolyzed. Yields lie in the order of 60-90% and the overall analysis time is approximately 3 h (ICP) or approximately 4 h (alpha measurement). Precisions reached are better than 15% relative. Detection limits lie at about 2 ppb (ICP) and 0.4 ppb (alpha measurement).
