HYDRIDE GENERATION OPTIMIZATION APPLIED TO As DETERMINATION IN WATER BY MICROWAVE PLASMA-ATOMIC EMISSION SPECTROMETRY

R. V. AZCARATE; S.M. AZACARATE; J.M. CAMIÑA; M. SAVIO

Florianópolis

Congreso; 18 Encontro Nacional de Química Analítica; 2016

Universidad Federal de Santa Catarina

A highly sensitive and simple method, based on hydridegeneration and atomic emission detection, for the determination of As in watersamples, has been developed. For this purpose, experimental design and optimizationtechniques were applied in order to optimize the hydride generation atomicemission spectrometry (HG?MPAES) procedure. Multivariate optimization by usingthe desirability function was used to find experimental conditions where thesystem generates desirable results. The effects of several factors affectingthe hydride generation efficiency -hydrochloric acid (1-20%), sodiumtetrahydroborate (0.2-2%), and potassium iodide (0.5-2%) concentrations andflow rates (0.5-10 ml.min-1) - were studied on the As signalintensity (193.695 nm). In addition, parameters affecting the hydridemeasurement -nebulizer gas pressure (80-240 kPa), viewing position ((-20)-20) -have been also investigated. This latter response was taken into account inorder to improve the quality of figures of merit. The ruggedness was evaluatedby means of an experimental 2-level fractional factorial design, in which theaccuracy was assessed when small changes were set in the studied parameters 1.The As determination was carried out by microwaveplasma atomic emission spectrometry (MPAES). Hydride generation was performedby the Multimode Sample Introduction System (MSIS), which uses thin filmhydride technology for significantly better performance than conventional nebulization2,3.Systematic optimization procedures was carried out byselecting an objective function, finding the most important factors andinvestigating the relationship between responses and factors by the so-calledresponse surface methods (RSM) 4. Acentral composite design was used, consisting of 30 experiments: combinationsof the (selected) independent variables. The accuracy of methods has beenverified by using Standard Reference Material 1643e, Trace Elements in Water.The developed method was applied to underground water of La Pampa, Argentina. 1 Leardi R, Experimental design in chemistry: A tutorial, AnalyticaChimica Acta, 652 (2009) 161?172.2 Dìdina J, Tsalev DL, Hydride Generation Atomic Absorption Spectrometry,Wiley, Chichester, 1995.3 www.agilent.com/chem/RunsOnAir4 Bezerra MA, Erthal Santelli R, Padua Oliveira E, Silveira Villar L ,Escaleira LA, Response surface methodology (RSM) as a tool for optimization inanalytical chemistry, Talanta , 76 (2008) 965?977.