Rigaku NEX GC EDXRF spectrometer

Applied Rigaku Technologies has announced an empirical method for the elemental analysis of Mg, Al, Si, Ca and Fe in limestone. Application Note #1108 demonstrates the effectiveness of the polarised excitation and Cartesian geometry design of the Rigaku NEX GC energy dispersive X-ray fluorescence (EDXRF) spectrometer to provide superior light element sensitivity.

Calcium-bearing minerals are widely used in agriculture, energy and road construction. Limestone has long been used as a key material in the construction of buildings and monuments, as well as the production of glass. It is used as a raw material in the production of quicklime, cement and mortar. Limestone is also used as a scrubber stone in the desulfurisation of flue gas and as a reagent in blast furnaces to extract iron from ore. Purified limestone has many uses as a calcium supplement in foods and animal feeds, and well as a whitener in cosmetics.

For this application, each sample is prepared by grinding to a fine, dry, homogeneous powder of <200 mesh (<75 µm particle size) using a ball mill. For measurement, 5 g of sample was pressed using 20 tons of pressure for 30 seconds to form a pellet.

The results shown indicate performance in a 'real-world' situation where a short analysis time of 140 seconds is required. Two secondary targets were used, the HOPG polarizer for light elements (Na-Cl) at 100 seconds and the Cu target for Fe at 40 seconds.