A HIGHLY EFFICIENT IONIC LIQUID-ASSISTED CLOUD POINT EXTRACTION TECHNIQUE FOR PRECONCENTRATION AND SPECIATION ANALYSIS OF TELLURIUM IN ENVIRONMENTAL SAMPLES USING ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY

LLAVER, MAURICIO; WUILLOUD, RODOLFO G.

Mendoza

Simposio; 15th RIO SYMPOSIUM ON ATOMIC SPECTROMETRY; 2019

Universidad Nacional de Cuyo

Despite being one of the rarest elements in the earth?s crust, tellurium has lately found several technological applications which have vertiginously augmented its demand.1 Furthermore, Te is a toxic heavy metal with significant differences in the toxicity of its species.2 Thus, the determination of Te in the environment is an increasingly important task, not only in terms of its total concentration, but also concerning its speciation analysis. In this work, a novel, efficient and highly sensitive ionic liquid-assisted cloud point extraction (IL-CPE) and preconcentration technique was developed for the determination and speciation analysis of Te, using 1-octyl-3-methylimidazolium chloride as an additive for improving the extraction efficiency obtained with Triton X-114. Te(IV) was complexed with ammonium pyrrolidine dithiocarbamate, extracted into the micellar IL/surfactant phase and then directly measured by electrothermal atomic absorption spectrometry (ETAAS). Total Te concentration was obtained after a pre-reduction step of Te(VI), while Te(VI) was calculated by subtracting Te(IV) from total Te. Different parameters related to the extraction and measurement processes, such as the type and concentration of IL and surfactant, time and temperature during the IL-CPE procedure and ETAAS conditions were thoroughly evaluated and optimized. An enhancement factor of 87 and a 90% extraction efficiency were achieved under optimal conditions. Limits of detection of 1.1 and 1.7 ng L-1 for Te(IV) and Te(VI), respectively, and relative standard deviations of 3.9% and 5.0% were obtained. Furthermore, the action mechanism of the IL on CPE was studied using the fluorescence of LAURDAN as a polarity probe and a decrease in the internal polarity of the extractant micelles was observed. The developed IL-CPE technique was successfully applied for Te speciation analysis in different water samples (tap, underground and seawater) and in soil and sediment leachates. Acknowledgements This work was supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Agencia Nacional de Promoción Científica y Tecnológica (FONCYT) and Universidad Nacional de Cuyo (Argentina).References [1] Dong, J., Jia, J., Cao, B., Wu, J., Materials Research Bulletin 115 (2019) 65-69. [2] Zare, B., Nami, M., Shahverdi, A.R., Biological Trace Element Research 180(2) (2017) 171-181.