PLUMBANE DETERMINATION BY HG-MIP-OES: STUDY OF THE VARIABLES AFFECTING ITS GENERATION, INTERFERENCE ANALYSES AND APPLICATION

MOLLO, A.; CORA JOFRE, F.; SIXTO, A.; PISTÓN, M.; SAVIO M.

Simposio; 15th Rio Symposium on Atomic Spectrometry; 2019

Among the hydride forming elements, lead volatilization by plumbane generation is not very extended for its determination1. Microwave induced plasma atomic emission spectrometry (MIP-OES) uses nitrogen to fuel the plasma reducing dramatically the associated cost. The aim of this work was to study the variables affecting both the plumbane generation and its determination by HG-MIP-OES. A new methodology for lead determination at trace levels was developed. Different plumbane generation conditions were evaluated. Results showed that 0.1 mol kg-1 HCl - 1.5 % w/w K3Fe(CN)6 ? 2 % w/w NaBH4 was a suitable balance between the hexacyanoferrate (III) enhancement of plumbane generation2 and the acidity of the generated wastes. Hydrogen ion was found to enhance the signal up to 0.3 mol kg-1 and then inhibit it at larger amounts. For concentration above 1.0 mol kg-1, signal was completely abated. Nitrate ion in turn was found to have a positive impact on lead´s signal for concentrations above 1.0 mol kg-1 NO3- (10 % w/w HNO3) enhancing the signal about 50%. For the formerly said, acid and nitrate concentration (the last generally deliberately added for sample digestion) are of concern for quantification purposes, so neutralizing and buffering the nitrate amount was mandatory. Analytical determinations were performed at 405,781 nm optimizing stabilization time of the chamber (20s), nebulizer flow (0.75 L min-1), pump speed (30 rpm), viewing position (0) and read time (5s). A linear response was found along the range of concentrations studied (from LOQ (10s) 0.82 up to 100 μg L-1); LOD (3,3s): 0.27 μg L-1. Trueness was assessed using a certified reference material (CRM) of water for low lead concentrations, and a CRM of soil and other CRM of mud for high ones. Mean recoveries were of 89, 91 and 78 % respectively. The incidence of acid and nitrate concentration in plumbane generation was evaluated. The novel developed method introduces HG-MIP-OES for lead determination with a promising performance for trace analysis.