Sequential injection analysis determination of sulphate in wastewaters by ultraviolet-spectrophotometry

Abstract

Foi desenvolvido um sistema de análise por injeção sequencial, baseado na formação do cátion FeSO 4 + e detecção espectrofotométrica a 355 nm, para a determinação de sulfato em águas residuais. Os principais interferentes foram avaliados. O sistema proposto é totalmente automático e permite o monitoramento de sulfato em amostras. O desvio padrão relativo (RSD) obtido foi inferior a 2,4%. O sistema apresentou uma resposta linear entre 10 e 1000 mg L -1 . A velocidade de amostragem obtida foi de 72 amostras por h.A sequential injection analysis system based on the formation of the cation FeSO 4 + and the spectrophotometric measuring of the absorbance at 355 nm has been developed for the determination of sulphate in wastewaters. The main interferents were also evaluated. The proposed system is fully automatized and is able to monitor sulphate in samples. The relative standard deviation (RSD) obtained was smaller than 2.4%. The linearity of response was obtained between 10 and 1000 mg L -1 . The sampling rate was 72 samples per hour.

Sequential injection analysis

“…Aluminium and mercury were employed as complexing agents to mask interferences from fluoride and chloride, respectively, in the determination of sulfate in wastewaters. 189 The agreement of the results with those achieved using a reference method was good provided that a background subtraction step was incorporated to allow for colorimetric interferences.…”

A review on sequential injection methods for water analysis

“…As a major dissolved component of rain water, sulfate is also commonly found in natural waters. All of the methods described for the determination of sulfate used spectrophotometric detection [86,116,122,150] were based on the turbidimetric reaction between sulfate and barium chloride. Only Lapa et al [122] described an alternative to turbidity measurement, namely the determination of sulfate by direct UV detection.…”