Journal article · Conference paper
Selective Flow Injection Analysis of Ultra-trace Amounts of Cr(VI), Preconcentration of It by Solvent Extraction, and Determination by Electrothermal Atomic Absorption Spectrometry (ETAAS)
A rapid, robust, sensitive and selective time-based flow injection (FI) on-line solvent extraction system interfaced with electrothermal atomic absorption spectrometry (ETAAS) is described for analyzing ultra-trace amounts of Cr(VI). The sample is initially mixed on-line with isobutyl methyl ketone (IBMK).
The Cr(VI) is complexed by reaction with ammonium pyrrolidine dithiocarbamate (APDC), and the non-charged Cr(VI)-PDC chelate formed is extracted into IBMK in a knotted reactor made from PTFE tubing. The organic extractant is separated from the aqueous phase by a gravity phase separator with a small conical cavity and delivered into a collector tube, from which 55 mul organic concentrate is subsequently introduced via an air flow into the graphite tube of the ETAAS instrument.
The operations of the FI-system and the ETAAS detector are synchronously coupled. A significant advantage of the approach is that matrix constituents, such as high salt contents, effectively are eliminated. Theextraction procedure was optimized by a simplex approach. A central composite design was subsequently employed to verify the estimated operational optimum.
An 18-fold enhancement in sensitivity of Cr(VI) was achieved after preconcentration for 99 s at a sample flow rate of 5.5 ml min-1, as compared to direct introduction of 55 mul of sample, yielding a detection limit (3sigma) of 3.3 ng l-1. The sampling frequency was 24.2 samples h-1. The proposed method was successfully evaluated by analyzing a NIST Cr(VI)-reference material, synthetic seawater and waste waters, and waste water samples from an incineration plant and a desulphurization plant, respectively.
Language: | English |
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Year: | 1999 |
Pages: | 1027-1044 |
Proceedings: | 9th International Conference on Flow Injection Analysis (ICFIA 98) |
ISSN: | 18733573 and 00399140 |
Types: | Journal article and Conference paper |
DOI: | 10.1016/S0039-9140(99)00044-2 |
ORCIDs: | 0000-0002-6856-9207 |
Assay of inorganic Cr(VI) Extraction of Cr(VI)-PDC complex FI-ETAAS On-line preconcentration of Cr(VI) Planteproduktion og stofomsætning