抄録
An analytical technique for determining the amounts of boron over 0.1 ppm in steel was investigated.
The sample (0.5g) was first dissolved with 10ml of hot nitric acid (35%), and then thoroughly dissolved with 10ml of hot mixed acid which consisted of three portions of phosphoric acid and one portion of sulfuric acid. Boron was separated by distillation as methyl borate. The methyl borate solution was transferred to a platinum dish, and heated up to 85± 5°C in an evaporating apparatus to decompose the methyl-borate into sodium borate with sodium hydroxide solution. This solution was evaporated completely using a water bath at the above temperature. 25ml of water was added to dissolve the residue, and the amounts of boron were determined from the intensity of the spectral line of 249.77nm by using an inductively coupled argon plasma (ICP) emission spectrometer.
This method exhibited good precision for the steel samples containing from 0.1ppm to 0.4% boron.
The coefficient of variation at 5ppm level was 4.0%.
