Use of a single calibration graph for the determination of major elements in geological materials by laser ablation inductively coupled plasma atomicemission spectrometry with added internal standards

The possibility of internal standardisation in laser ablation inductively c oupled plasma atomic emission spectrometry (LA-ICP-AES) of geological mater ials by added Sc2O3 and Y2O3 has been examined to cover the wide range of c oncentrations of major and minor constituents both in silicate rocks and li mestones. A Nd:YAG laser (355 nm, 10 Hz, 10 mJ per shot) was used for the a blation of discs obtained by fusion of the mixture of samples and oxides of Sc and Y with lithium tetraborate. The flux/sample ratio was in the range from 6 to 10. The contents of analytes were within the concentration range from hundredths to tens of percentage. The trace elements copper and nickel were studied, too. An ICP emission spectrometer OPTIMA 3000 DV was used fo r the measurement of Si, Al, Ca, Mg, Sr, Ba. Fe, Ti, Mn, Ni, Cu. Na and K a nalyte lines and Y and Sc reference lines in the axial observation mode. Th e long-term and the short-term repeatability of measurement were improved b y employing scandium or yttrium internal references lines for the above ana lytes from 6% to 1.5% of RSD and from 2.4% to 1.0% of RSD, respectively. Th e correlation of signals with concentrations was improved in terms of the c orrelation coefficient r from 0.90-0.97 to 0.98-0.998 and the relative unce rtainty on the centroid of concentrations was improved 2-3 times. A single calibration graph covering the concentration range both in silicates and ca rbonates is possible for each of elements. as the matrix effects are compen sated for by internal standards and the excess of Li2B4O7.