Determination of trace elements in zeolites by laser ablation ICP-MS |
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Authors: | C Pickhardt I B Brenner J S Becker H-J Dietze |
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Institution: | (1) Zentralabteilung für Chemische Analysen, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany, DE;(2) 9 Dishon Street, Malkha BGU-EAL, 96956 Jerusalem, Israel, IL |
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Abstract: | Laser ablation inductively coupled plasma mass spectrometry using a quadrupole-based mass spectrometer (LA-ICP-QMS) was applied
for the analysis of powdered zeolites (microporous aluminosilicates) used for clean-up procedures. For the quantitative determination
of trace element concentrations three geological reference materials, granite NIM-G, lujavrite NIM-L and syenite NIM-S, from
the National Institute for Metallurgy (South Africa) with a matrix composition corresponding to the zeolites were employed.
Both the zeolites and reference materials were fused with a lithium borate mixture to increase the homogeneity and to eliminate
mineralogical effects. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS
relative sensitivity coefficients (RSCs) of chemical elements and calibration curves were measured using the geostandards.
The experimentally obtained RSCs are in the range of 0.2-6 for all elements of interest. Calibration curves for trace elements
were measured without and with Li or Ti as internal standard element. With a few exceptions the regression coefficients of
the calibration curves are better than 0.993 with internal standardization. NIM-G granite reference material was employed
to evaluate the accuracy of the technique. Therefore, the measured concentrations were corrected with RSCs which were determined
using lujavrite reference material NIM-L. This quantification method provided analytical results with deviations of 1–11%
from the recommended and proposed values in granite reference material NIM-G, except for Co, Cs, La and Tb. The relative standard
deviation (RSD) of the determination of the trace element concentration (n = 5) is about 1% to 6% using Ti as internal standard
element. Detection limits of LA-ICP-QMS in the lower μg/g range (from 0.03 μg/g for Lu, Ta and Th to 7.3 μg/g for Cu, with
the exception of La) have been achieved for all elements of interest. Under the laser ablation conditions employed (λ: 266
nm, repetition frequency: 10 Hz, pulse energy: 10 mJ, laser power density: 6 × 109 W/cm2) fractionation effects of the determined elements relative to the internal standard element Ti were not observed.
Received: 7 April 2000 / Revised: 25 May 2000 / Accepted: 31 May 2000 |
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