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Determination of Trace Metals in Sodium Dithionite‐Citrate Extracts of Soils and Sediments by Atomic Absorption
Author(s) -
Jenne E. A.,
Ball J. W.,
Simpson C.
Publication year - 1974
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1974.00472425000300030021x
Subject(s) - dithionite , chemistry , sodium dithionite , extraction (chemistry) , ammonium hydroxide , methyl isobutyl ketone , inorganic chemistry , atomic absorption spectroscopy , dissolution , nuclear chemistry , solvent , environmental chemistry , chromatography , organic chemistry , physics , quantum mechanics , enzyme
A general method has been developed for the analysis of Co, Cu, Ni, Mo, and Zn in dithionite‐citrate extracts of soils and sediments. Because of the high Zn content of dithionite, it is necessary to preclean the dithionite‐citrate solution before it is used to extract soils or sediments. This precleaning lowers the detection level significantly for other trace elements as well. Since Fe causes flame interferences in the determination of several first transition series elements by atomic absorption, the size of the individual sample aliquot taken to chelation‐solvent concentration is varied to provide a constant quantity of Fe (5,000 µ g). The standards and blanks are adjusted to the same Fe content. This approach is necessitated by the wide differences in the Fe concentrations of the dithionitecitrate extracts. Following pH adjustments and addition of ammonium‐1‐pyrrolidine dithiocarbamate, the trace metals (and Fe) are concentrated via two successive 10‐ml methyl isobutyl ketone extractions. Quantities of Fe much greater than 5,000 µ g interfere in the solvent concentration step. Natural organics released by the dissolution of free‐Fe and ‐Mn oxides, to the extent that they are represented by fulvic acids, do not cause any significant interference in the ammonium‐1‐pyrrolidine dithiocarbamate methyl isobutyl ketone extraction of the trace metals due to the releasing effect of the Fe present.