DIRECT POWDER INTRODUCTION INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY WITH A PHOTODIODE ARRAY SPECTROMETER

A direct powder introduction inductively coupled plasma (DPI-ICP) atomic emission system has been coupled to a PLASMARRAY (LECO Inc.) photodiode array spectrometer. Chelex-100 samples containing spikes of elements ranging from 11 ppm to 1470 ppm have been used to evaluate the precision of element to element ratios, and for the estimation of the detection limits of 11 elements. Detection limits for Cd (0.11 ppm), Hg (1.7 ppm), Sc (2.1 ppm). Y (1,8 ppm) and Cu (3 ppm) were calculated for introduction of dry Chelex-100 powder. The precision of the ratio of emission intensities of Ni, Sn, Co. Mn and Y to the emission intensity of In (considered to be the internal standard element) were 4%, 2%, 2%, 2% and 3% relative standard deviation respectively, for 15 repeat 10 s integration measurements while introducing Chelex-100 into the plasma. Mixtures of a geological reference material (including NIM-D, NIM-G, NIM-L, NIM-N, NIM-P, or NIM-S) and Chelex-100 (1:3 by weight) were used to evaluate system performance with complex samples. It was considered impractical to carry out measurements on these samples with more than a few slots of the multielement spectral preselection mask open. The relative standard deviation (R.S.D.) of the ratio of elements contained in the geological sample vs those on the Chelex-100 were between 2% and 16%. The R.S.D. of the ratio of elements wherein both were found on the geological material was between 2 and 8%. Detection limits for Ni (7 ppm), Cr (25 to 85 ppm) and Y (1.5 ppm) were estimated for the geological materials (1:3 by weight with Chelex-100).