Electrochemical generation of antimony volatile species, stibine, using gold and silver mercury amalgamated cathodes and determination of Sb by flame atomic absorption spectrometry Jessenia Ordoñes a , Lenys Fernández b,n , Hugo Romero a , Patricio Carrera c , José Alvarado b a Facultad de Ciencias Químicas y de la Salud, Universidad Técnica de Machala, Apartado, 070151 Machala, Ecuador b Departamento de Química, Universidad Simón Bolívar, Apartado 89000, Caracas 1080-A, Venezuela c Hidroecuador, Apartado, EC1701 Quito, Ecuador article info Article history: Received 19 February 2015 Received in revised form 6 April 2015 Accepted 7 April 2015 Available online 16 April 2015 Keywords: Electrochemical antimony hydride genera- tion Atomic absorption spectrometry Stibine Marine sediment samples abstract The electrochemical generation of antimony volatile species (stibine) using Au and Ag mercury amal- gamated cathodes is described. Compared with some other cathode materials commonly used for electrochemical hydride generation, performance of the amalgamated cathodes is substantially better in the following aspects: higher interference tolerance, higher erosion resistance and longer useful working time. Using the amalgamated cathodes, it could be shown that interferences from major constituents at high concentrations, especially from transition metals, affecting stibine generation are not as significant as they are using other cathode types in regards to sensitivity and useful working time. Results obtained using the Ag/Hg amalgamated cathode showed a slightly higher sensitivity than the corresponding results obtained using the Au/Hg cathode. The Au/Hg cathode, which to our knowledge has not pre- viously been used to generate stibine, showed considerably longer useful working time than the Ag/Hg one. The optimum catholytes for electrolytic generation of stibine (SbH 3 ) from Sb(III) and Sb(V) using the Au/Hg electrode were aqueous solutions containing 0.5 mol L À1 H 2 SO 4 and 0.5 mol L À1 HCl, respectively. Under optimized conditions, using the Au/Hg cathode and comparing to aqueous standards calibration curves, detection limits (3s) of 0.027 mgL À1 for Sb(III) and 0.056 mgL À1 for Sb(V), were obtained. To check accuracy a marine sediment reference material (PACS-2, NRC) was analyzed using a method purportedly developed for this task. Good agreement, 95% confidence, was found between the certified and the experimental values for Sb. The proposed method was also applied to the determination of Sb in aqueous solutions of marine sediments samples from Comuna de Bajo Alto Provincia de El Oro—Ecuador. Recoveries of five replicate determinations of these samples were in the range of 98–103% thus showing acceptable accuracy in the analysis of real samples. & 2015 Elsevier B.V. All rights reserved. 1. Introduction Antimony and its derivatives are amongst the compounds to which EPA and ECC have given high priority as contaminants [1]. Antimony contamination by exposition seems to be significantly higher than contamination by ingestion due to the fact that the content of Sb in food and drinkable water is generally considerably lower than its content in air or in waters including those located near industrial areas [2]. Existence of Sb in the ambient is a con- sequence of the use of Sb containing substances employed in fabrication of glass, ceramics, car's brakes, flame retardants, etc. [3–6]. Long exposition to relatively low Sb concentrations in air, around 9 mg m À3 , could lead to skin and eye irritation, stomach ulcers and pulmonary affections [7]. Determination of Sb in ambient air is not a common procedure probably because the element is usually found at very low concentration levels in this type of sample. Antimony concentration in the earth crust is around 0.7 mgg À1 , in sea water is between 0.1 and 0.5 mgL À1 , in places near to lead and copper processing plants is 0.0005– 1.1 mg kg À1 , and 0.0001 mg g À1 , respectively [8]. Due to these low concentration levels Graphite furnace atomic absorption spectro- metry (GFAAS) has been the choice to determine Sb. However, GFAAS is a very expensive analytical approach to be used for routine analysis of large number of samples due to the high cost of the graphite tubes. Using chemical hydride generation, CHG, or electrochemical hydride generation, EcHG, for sample introduction into the spectrometer, in order to avoid the inefficiency of pneu- matic nebulization, makes flame atomic absorption spectrometry, Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/talanta Talanta http://dx.doi.org/10.1016/j.talanta.2015.04.025 0039-9140/& 2015 Elsevier B.V. All rights reserved. n Corresponding author: Tel.: þ58 212 9063979; fax: þ58 212 9063961. E-mail address: lfernandez@usb.ve (L. Fernández). Talanta 141 (2015) 259–266