Determination of Trace Lead in Uranium-bearing Geological Samples by Inductively Coupled Plasma-Optical Emission Spectrometry with Double Capillary On-line Interference Correction

Measured lead contents in geological samples were commonly lower than real values because of matrix elements interference during Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analyses. In this study, U-bearing geological samples were dissolved by hydrofluoric acid, nitric acid, perchloric acid, and hydrochloric acid. Trace lead was determined by ICP-OES with double capillary on-line interference correction. The interferences of matrix elements on lead were studied using double capillary. Iron and Al had negative interferences on lead, whereas a specific concentration of U, Ba, Ti, Ca, Mn, Mg, K and Na almost had no interferences on lead. The standard curve was established using double capillary according to the contents of Fe and Al in different test solution. The unknown sample was diluted simultaneously, which reduced the matrix effects of Fe and Al. The detection limit was 1.5 μg/g, and the RSD was less than 5%. Compared with the common interference correction method, the double capillary on-line interference correction method can establish a standard curve quickly using different interference correction test solutions according to different matrices. Moreover, sample solution does not need to be secondly diluted, saving the reagent. This method is suitable for rapid determination of batch samples with similar matrices.