Determination of uranium in complex geological samples by inductively coupled plasma-optical emission spectrometry (ICP-OES): spectral interference of aluminium, iron, calcium and titanium

Rapid, sensitive, environmental friendly and accurate method for determination of trace uranium concentrations in complex geological samples is an absolute necessity during the exploration for atomic minerals. Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) has been demonstrated to have the capability to meet the above requirements. However, the effects of major matrix elements become detrimental to achievable analytical figures of merit. This study reports effect of concomitant Fe, Al, Ca and Ti in solution on the optical emission intensity of uranium at two different wavelengths 367.007 nm and 409.014 nm and at different uranium concentrations (2, 4, 6, 10 ppm). The intensity of emission line at 367.007 nm is enhanced by Fe whereas; Al, Ca and Ti did not affect it considerably. All the matrix elements showed depressing effect on the intensity of 409.014 nm line among which Fe showed the significant effect due to self absorption. Optimization of other instrumental parameters is also discussed. Considering the interferences of major elements, an analytical method of matrix matching calibration of the ICP-OES for 409.014 nm line (RF:1200 W), has been developed for accurate determination of uranium in geological samples. The values obtained by this method were comparable with those obtained through LED Fluorimetry and Pellet Fluorimetry. Calibration ranged from 0.5 to 10 mg/L uranium. (author)