Caprolactam for industrial use — Determination of colour of 50 % aqueous caprolactam solution, expre...
The absorbance of a 50 % aqueous caprolactam solution is spectrometrically measured at a wavelength of 390 nm and an optical path length of 50 mm. The result is expressed in Hazen units by multiplying the absorbance measured by a constant factor equal to 150. This factor is derived from measurements of absorbance of diluted standard solutions of platinum-cobalt scale.
Crude sodium borates for industrial use — Determination of total and alkali-soluble calcium and magn...
A test solution is prepared by one of the two following ways: a) fusion of a test portion with sodium carbonate in the case of total calcium and magnesium contents, and b) from an aliquot portion of "solution A" (ISO 2217) for alkali-soluble calcium and magnesium contents. Lanthanum ions are added to the solution to suppress certain interferences. The solution is aspirated into an…
Crude sodium borates for industrial use — Determination of total and alkali-soluble calcium and magn...
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…
