Reference number
ISO 6920:1984
ISO 6920:1984
© ISO 2024
ISO 6920:1984
Crude sodium borates for industrial use — Determination of total and alkali-soluble calcium and magnesium contents — Titrimetric method
Edition 1
1984-11
1984-11
Withdrawn
Abstract
The calcium content is determined by titration of an aliquot portion of the test solution with ethyleneglycol-bis-(2-aminoethyl)-N,N,N',N'-tetra acetic acid, disodium salt (EGTA) solution using 2-carboxy-2'-carboxy-2'-hydroxy-5'-sulphoformazylbenzene (Zincon) as indicator. The combined magnesium and calcium contents are determined by titration of a further aliquot portion of the test solution with ethylenediaminetetra-acetic acid, disodium salt (EDTA) solution, using Mordant black 11/potassium chloride as indicator, after addition of triethanolamine solution and buffer solution. The magnesium content is calculated by difference.