Summary
For the convenient and sufficiently accurate determination of AsO4 3− ions in technical products containing different filling, suspending and colouring materials, as well as impurities—e.g. for the assay of arsenate containing plant protecting materials—the following procedure is recommended.
About 5 g of the sample is dissolved, resp. extracted with 4 N hydrochloric acid, and aliquots of the clear filtrate are titrated after elimination of the interfering metal ions by combining them with complexing agents (potassium cyanide and disodium ethylenediamin tetraacetic acid) in a properly buffered medium. The titration with 0.1 M MgSO4 solution is conducted in the presence of eriochrome black T solution as indicator, first time for eliminating the excess of EDTA added, and afterwards to determine the AsO4 3− ions, after adding about 40% of ethanol.
The procedure may be useful chiefly for serial routine analyses.
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References
Bakács-Polgár, E.: Magyar Kémiai Folyóirat 60, 229 (1954); cf. Z. analyt. Chem. 147, 123 (1955).
Bakács-Polgár, E., and L. Szekeres: Magyar Kémiai Folyóirat 62, 296 (1956); cf. Z. analyt. Chem. 157, 367 (1957).
Erdey, L.: Einführung in die chemische Analyse (Ungarisch) Bd. II, p. 181. Budapest 1951.
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Kaiser, H., and H. Specker: Z. analyt. Chem. 149, 46 (1956).
Schulek, E., and P. v. Villecz (as quoted by L. Erdey): Einführung in die chemische Analyse (Ungarisch) Bd. II, pp. 148, 154, 155 (1955w).
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Winkler, L.: Ausgewählte Untersuchungsverfahren für das chemische Laboratorium, pp. 103–104. Stuttgart 1931.
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The authors are indebted to engineer L. Fokássy, department leader at the State Institute for Agricultural Quality Control, as well as to engineeress P. Fodor and Mr. Gy. Josepovits, scientific collaborators of the Research Institute for Plant Protection, for kindly supplying some of the samples for the experiments.
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Bakács-Polgár, E., Szekeres, L. & Láng, B. Titration of AsO4 3− ions with 0.1 M magnesium sulphate solution in the presence of Ca2+, Mg2+, Fe3+, Cu2+ ions and some other foreign substances. Z. Anal. Chem. 158, 14–20 (1957). https://doi.org/10.1007/BF00457362
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DOI: https://doi.org/10.1007/BF00457362