A flow injection procedure using Layered Double Hydroxide for on line pre-concentration of fluoride

Abstract

This work showed a flow system designed with solenoid valves for preconcentration of fluoride using SPADNS method in water samples. The analyte was preconcentrated in a mini-column coated with Layered Double Hydroxides (LDH) used as adsorbent. Then, the fluoride ions were eluted with 0.5molL sodium hydroxide and determined by spectrophotometry. The variables that affect the system such adsorbent mass, type of eluent, solutions flow rate, reagent concentration and pH effect were critically evaluated. Under optimized conditions, the detection limit, coefficient of variation, linear range and preconcentration factor were estimated at 15µgL (99.7% confidence level), 0.8% (500µgL, n = 10), 50-500µgL and 10, respectively. The accuracy of the method was evaluated by analysis of ALPHA APS 1076 (Simulated Rain Water) certified material, the values were not significantly different at a 95% level of confidence. The method was applied for fluoride determination in water samples and the levels found were below the maximum values established by Brazilian environmental and health legislations.

Estratégias de microextração em fases sólida e líquida para determinação de cobre e cromo em água empregando técnicas eletroanalíticas e espectrométricas

“…Esse material apresenta propriedades estruturais, químicas e físicas (capacidade de troca (Vieira, 2009), grande área superficial, muitas vezes a não dependência do ajuste de pH para a retenção de íons, uma vez que este material apresenta uma capacidade tamponante (Rocha et al, 2018) (Crepaldi e Valim, 1998): (Bezerra, 2017), (Maltez, 2003a), (J. Ruzicka, 1988.-a).…”