Effect of matric absorption on sensitivity

Abstract

An ore specimen consisting predominantly of calcium and barium carbonates contained traces of nickel. A specimen containing no barium sulphate with a mass absorption coefficient for Ni Kα of 124 gave the following data

240 c/s per % for nickel

background 120 c/s

• (a) Estimate the lower limit of detection for nickel in an analysis time of 200 s.

• (b) What would be the effect on this detection limit of adding 20% of barium sulphate to the specimen, assuming that the c/s per % value is inversely proportional to the matrix absorption? Assume also that the background is reduced by 8% by the addition of the barium sulphate. The atomic weights of Ba = 137.4, S = 32.1 and O = 16.