Desenvolvimento de procedimento analítico para determinação fotométrica de mercúrio em sedimentos e águas doces empregando os processos fluxo-batelada e multicomutação em fluxo

Abstract

DEVELOPMENT OF AN ANALYTICAL PROCEDURE FOR PHOTOMETRIC DETERMINATION OF MERCURY IN SEDIMENT AND DRINKING WATER EMPLOYING THE FLOW-BATCH AND FLOW MULTICOMMUTATION PROCESSES: This work deals with a multicommuted flow-batch setup and a photometric procedure for the determination of mercury in waters and sediments. The setup was designed to exploit facilities achieved by associating flow-batch and multicommuted flow analysis approaches, thus allowing the implementation of a versatile solvent extraction and pre-concentration strategy. The method was based on the reaction of Hg(II) with dithizone in chloroform medium, which was used as a extracting organic solvent. The flow analysis system constituted by a homemade syringe pump module, a set of solenoid valves, two mini-pumps and a flow-batch chamber. The homemade photometer comprised a light emitting diode (LED), a photodiode and a homemade flow cell (50 mm long). The flow system and the photometer were controlled through an Arduino Due board, running a software wrote for this purpose. After selecting the better operational conditions, the effectiveness of the proposal was evaluated by determining mercury in waters. Aiming to accuracy assessment, sample were also analyzed employing an independent method. Accuracy was accessed using the spiking methodology and recovery ranging from 92 to 108 % was observed. Other profitable features such as a linear response ranging from 0.5 to 10.0 µg L-1 (r = 0.9984); a limit of detection 0.38 µg L-1 Hg(II) (n = 10); consumption of dithizone and chloroform 0.18 mg L-1, and 800 µL per determination, respectively; coefficient of variation (n = 10) 2%; and a sampling rate of 20 determination h-1 were also achieved.