Properties and analytical applications of the heteropolymolybdates of phosphorus, arsenic, silicon and germanium?III1Examination of two- and three-component systems without separation

Halász, A.

doi:10.1016/0039-9140(71)80090-5

Cited by 26 publications

(8 citation statements)

References 5 publications

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“…Reduction methods to heteropoly blues suffer problems of longer reaction time, deviations from Beer's law, unstable reagents and products, and high blank absorbances. Alternatively, another procedure measures the 12-MPA formed and then the combined 12-MPA and 12-MSA concentrations in a less acidic solution (24). However, since the 12-MSA, 12-MPA, and other heteropolymolybdate concentrations vary with acidity, this procedure can also be prone to error.…”

Section: Literature Citedmentioning

confidence: 99%

Simultaneous reaction-rate determinations of phosphate and silicate

Kircher¹,

Crouch²

1983

Anal. Chem.

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Section: Literature Citedmentioning

confidence: 99%

Simultaneous reaction-rate determinations of phosphate and silicate

Kircher¹,

Crouch²

1983

Anal. Chem.

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“…It is known that silicate ion also forms HPC with molybdate. To eliminate the silicate artifact, arising due to HPC formation during molybdate interaction with the quartz capillary matter, well‐known masking agent, sodium perchlorate 13, was introduced into the electrolyte. Using the ratio of molybdate to perchlorate equal to 1:1 we did not detect the HPC of silicate.…”

Section: Resultsmentioning

confidence: 99%

“…There are a few publications concerning the application of the chemical reactions of arsenate or arsenite ions for their photometric determination 10–23; as for MMA and DMA the similar reactions are not mentioned in literature. According to published data molybdoarsenic complexes of arsenate, MMA and DMA ions are synthesized and structurally characterized.…”

Section: Introductionmentioning

confidence: 99%

Arsenic speciation in natural and contaminated waters using CZE with in situ derivatization by molybdate and direct UV‐detection

2009

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A simple and sensitive procedure for simultaneous determination of arsenate, arsenite, monomethylarsonate and dimethylarsinate (DMA) ions in waters using CZE with chemical derivatization in situ and UV-detection at 250 nm was developed. The separation was performed in a fused-silica capillary using solution containing sodium molybdate and sodium perchlorate as electrolyte. Molybdate forms heteropolycomplexes with arsenic species in low acidic media, while sodium perchlorate masks silicate ion. The analysis conditions were optimized; the best results were achieved with the electrolyte consisting of 10 mM Na(2)MoO(4) and 10 mM NaClO(4) at pH 3.0 using negative voltage and pneumatic injection of the sample. Nevertheless, the signal of arsenite ion was not detected, probably because of its instability. Arsenite ion was quantified as a difference between arsenate ion contents after and before oxidation by bromine water. The detection limits for the fresh water at the level of 5.0 microg/L for As(III) and As(V), 16 microg/L for DMA and 20 microg/L for MMA were achieved. The reproducibility varied in the range of 0.06-0.25 relative units. To reduce the interferences of the sample salinity an addition of organic substances and isotachophoretic effect were used.

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“…Numerous studies have been performed to develop the sensitivity [2][3][4][5] and selectivity [6][7][8][9][10][11] of the polyheteromolybdic acid and polyheteromolybdenum blue procedure, which is a wellknown method to determine the silicate and phosphate. However, the selectivity for the determination of phosphate and silicate in the presence of each other was not sufficient for a direct determination of these anions in material samples.…”

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Simultaneous Determination of Phosphate and Silicate by First-Derivative Spectrophotometry

2001

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Phosphate and silicate have been involved in an environmental problem. The problem has serious consequence in view of the widespread utilization of phosphate and silicate in water softening, surfactants and many other applications. Phosphates were introduced into lakes from inadequately treated sewage containing detergents and water from humans and animals. If in excess quantity, they lower the quality of lake water and cause the death of living organisms by stimulating the growth of alga. Silicate serves as a micronutrient for diatomaceous algae. This type of algae converts soluble silicate to solid silicate, and thus increases the insoluble material percentage of water if used finallys for drinking. 1 Numerous studies have been performed to develop the sensitivity 2-5 and selectivity 6-11 of the polyheteromolybdic acid and polyheteromolybdenum blue procedure, which is a wellknown method to determine the silicate and phosphate. However, the selectivity for the determination of phosphate and silicate in the presence of each other was not sufficient for a direct determination of these anions in material samples. Two well-known procedures were utilized for the simultaneous determination of phosphate and silicate. One was based on kinetic differences in the rates of the formation of two molybdoheteropoly acid 12 and molybdoheteropoly blue. 13 The other procedure was based on utilizing segment flow analysis (FIA). 14 However, these procedures require careful control of the experimental conditions. Derivative spectrophotometry has been found to useful for the direct analysis of mixtures. 15,16 The simultaneous determination of phosphate and silicate in material samples by a simple and inexpensive method was difficult, due to mutual interference between two anions. The main purpose of the present work was the simultaneous determination of phosphate and silicate by a simple, sensitive and selective method utilizing a relatively inexpensive and popular apparatus. Experimental MaterialsAll chemicals were of analytical-reagent grade and were stored in polyethylene bottles to prevent silicate leaching. Twice-distilled water was used throughout. A phosphate stock solution (1 mg PO4 3-mL -1 : a 0.3582 g of oven-dried KH2PO4) was dissolved in 250 mL of water. A silicate stock solution (1 mg SiO3 2-mL -1 : a 0.6969 g of Na2SiO3·5H2O) was dissolved in 250 mL of water. A molybdenum(VI) solution (0.02 M: a 6.1790 g of (NH4)6Mo7O24·4H2O) was dissolved in 250 mL of water. An acidic molybdate solution (1.6 × 10 -2 M (≈2%): a 2.0 g of (NH4)6Mo7O24·4H2O) was dissolved in 100 mL of 0.6 M hydrochloric acid. 1-Amino-2-naphthol-4-sulfonic acid reagent (ANSA) (3.0 × 10 -3 M) was prepared as reported elsewhere. 1 Stannous chloride (1.3 × 10 -2 M (0.25%): a 0.625 g of SnCl2) was dissolved in 250 mL of 0.15 M hydrochloric acid. Detergent and wastewater samples were obtained from Lang Silicate, and sulfonation factories for synthetic detergents, Tenth of Ramadan City, Egypt. Tap water was obtained from the municipal water of the cities Cairo a...

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Properties and analytical applications of the heteropolymolybdates of phosphorus, arsenic, silicon and germanium?III1Examination of two- and three-component systems without separation

Cited by 26 publications

References 5 publications

Simultaneous reaction-rate determinations of phosphate and silicate

Simultaneous reaction-rate determinations of phosphate and silicate

Arsenic speciation in natural and contaminated waters using CZE with in situ derivatization by molybdate and direct UV‐detection

Simultaneous Determination of Phosphate and Silicate by First-Derivative Spectrophotometry

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