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

FLORENCIA CORA JOFRE; MARIANELA SAVIO; ALICIA MOLLO; MARIELA PISTÓN; ALEXANDRA SIXTO

Mendoza

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 L-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 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 concentrations studied range (from LOQ (10s) 0.82 up to 100 μg L-1). A limit of detection (LOD (3,3s)) of 0.27 μg L-1 was achieved, 100-fold better than that attained with MIP OES without HG. Trueness was assessed using a certified reference material (CRM) of water for low lead concentrations, and a CRM of soil and also mud for high ones. Mean recoveries were of 89, 91 and 78 % respectively. This study allowed evaluating the incidence of acid and nitrate concentration in plumbane generation. To the best of our knowledge, this is the first attempt that HG-MIP OES was performed for lead determination with a promising performance for trace analysis.