Flow injection spectrophotometric determination of silicate based on the formation of the ion associate between molybdosilicate and Malachite Green

Abstract

A flow injection method is proposed for the determination of silicate. The method is based on the formation of an ion associate between molybdosilicate and Malachite Green. A three-channel manifold was used in the development of the reaction. The sample injected into a water carrier reacts with a molybdate solution and finally the ion associate is formed from merging molybdosilicate and Malachite Green solutions. The influence of chemical, physical and flow variables on the absorbance was studied spectrophotometrically at 645 nm. Experimental conditions to avoid the adsorption of the ion-associate complex on the surfaces of the flow system were also investigated. The precision of the method is better than 2.0% and the detection limit is 14 ng of SiOz per millilitre. The sample throughput is 70 samples h-l. The method proposed has been applied to the determination of silicate in natural waters. Results are in a good agreement (within 2%) with those obtained by the standard spectrophotometric method.

Spectrophotometric Determination of Arsenic in Water Samples Based on Micro Particle Formation of Ethyl Violet- Molybdoarsenate

“…22,23 It has also been used in the determination of silicate. [24][25][26] Matsubara et al reported on the collection of aggregates on a membrane filter in their work on the determination of phosphate and arsenate using Malachite Green. 27 Light-scattering detection was also studied for the determination of phosphate using tetrakis(1-methyl-pyridinium-4-yl)porphyrin.…”

Novel flow injection-fluorometric method for the determination of trace silicate and its application to ultrapurified water analysis

“…Silicate present at sub-ppm levels did not form molybdosilicate at temperatures below 40 o C. As the temperature is raised above 40 o C, There is a gradual increase in the amount of molybdosilicate which reach the required value at about 100 o C [14,18]. The effect of temperature was examined from 40 o C to 110 o C and the results were displayed in Fig.5.…”

Determination of heavy metals in milk by potentiometric stripping analysis using a home-made flow cell

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