An emission-spectrographic method for the determination of boron in nuclear-grade graphite

Abstract

A rapid, highly sensitive method is described for the spectrographic determination of boron in nuclear-grade graphite. Boron, present in the sample in the form of boron carbide (B₄C), is volatilised as the trifluoride by the addition of 1 per cent. of Kel-F powder (polychlorotrifluoroethylene) to the samples. The samples, containing 500 p.p.m. of silicon as the internal standard, are excited by a 10-A d.c. arc in the presence of an argon-controlled atmosphere. A linear relationship between the intensity ratio of the lines boron 249·773 nm and silicon 245·214 nm and the boron concentration is established in the boron concentration range 0·1 to 5 p.p.m. The relative standard deviation, calculated from twelve determinations on each sample, ranges from ±8 per cent. (at 5 p.p.m. of boron) to ±11 per cent. (at 0·1 p.p.m. of boron).