Use of a single air segment to minimise dispersion and improve mixing in sequential injection: turbidimetric determination of sulphate in waters

Abstract

In this work, we propose the use of an air segment in a sequential injection system to simultaneously improve the overlapping of the stacked zones and minimise dispersion. This strategy was developed for the determination of sulphate in natural and wastewaters. Barium chloride was used as a precipitating agent and the turbidity of the suspension formed was measured at 420 nm. Analysis was performed without sample pre-treatment and the system was able to monitor sulphate concentration at a rate of at least 20 determinations per hour. Slightly different analytical sequences were developed for natural and wastewaters in order to minimise specific interferences. Direct determination of sulphate was possible within a concentration range of 10-100 and 16-100 mg SO(4)(2-) L(-1) for natural and wastewaters, respectively. Results obtained were comparable with those of the reference method with relative deviations lower than 5%. Relative standard deviations between 1.6% and 3.3% were found.

Development and validation of an analytical method for the extraction and quantification of soluble sulfates in red clay

“…Turbidimetric conditions: In order to select the most favorable turbidimetric conditions for the determination of soluble sulphates in clays, different wavelengths used in diverse studies were tested for the determination of sulphates by turbidimetry methods in matrices like water and soils [25][26][27][28][29][30][31][32][33][34][35]. Such conditions were tested and modified to obtain better results.…”

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.…”

Indirect determination of chloride and sulfate ions in ethanol fuel by X-ray fluorescence after a precipitation procedure

“…The reaction kinetic, the extent of interference (from both cationic and anionic species) as well as the structure and solubility of the BaSO 4 and AgCl precipitates formed are influenced by solution acidity [14][15][16]. Therefore, different nitric acid concentrations in the precipitant reagent solution were tested: 0.01 mol L −1 , 0.05 mol L −1 and 0.1 mol L −1 .…”