An absorptiometric aluminon method for the determination of beryllium in iron and steel has been presented by separating beryllium from ironetc. with sodium hydroxide solution and hydrogen peroxide mixture and masking the interfering elements as aluminum etc. with EDTA.
The recommended procedure is as follows : Weigh 2g sample into a 500m
l flask, dissolve with 20m
l of a mixed acid (HCl 1+HNO
3 1) and successively with 30m
l of perchloric acid, evaporate to fumes of perchloric acid, oxidize chromium to dichromate, allow to cool down to room temperature, and add approximately 50m
l of water to dilute to the mark. Pipet 120m
l from this solution into the mixture of 30m
l of hot sodium hydroxide solution (25%) and 5m
l of hydrogen peroxide (3%), transfer the solution to a 100m
l. Volumetric flask after boiling for 3 min., dilute to the mark, and filter with a dried filter. Pipet 50m
l from the filtrate into a 100m
l beaker, just neutralize it with hydrochloric acid (1+1) and add excessive 0.25m
l.
Transfer the solution to a 100m
l volumetric flask, cool, add 3m
l of EDTA solution (2.5%) and 15m
l of aluminon-buffer solution (0.1%) with 1m
l of gum arabic, and immerse the whole in boiling water for 4 min. Cool down to room temperature, dilute to the mark with water, and measure the absorbance with filter S 53. A blank test using the pure iron is followed by the same procedure. Calculate the difference of the absorbances and determine the amount of beryllium from the calibration curve.
The time required for an analysis was about 2530 min.
In addition, as compared with the aluminon method, the Eriochrome cyanine R method and the Qinalizarin method improved by the author, Eriochrome cyanine R method was found to be better than the others on the rapidity and sensitivity, although this method required more or less skill to control pH of the solution. The aluminon method was found to have an advantage in the simplicity of operation and the lower blank absorbance.
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