Section 4: optical methods. Ultra-violet absorptiometric determination of arsenic as 12-molybdoarsenic acid

Wadelin, Coe W.; Mellon, M. G.

doi:10.1039/an9527700708

Cited by 23 publications

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“…12 It is also well known that solvent extraction with ethyl acetate, 1-butylalcohol, 2-methyl-1-propylalcohol, and so on, makes the sensitivity high. 5,[13][14][15][16][17][18][19][20][21] Motomizu et al reported that the formation of colored ionassociate between molybdophosphate and Malachite Green could be utilized to determine phosphorus in the ultra-trace range from 0.018 to 1.0 ng cm -3 . 22 These highly sensitive methods contain a few careful procedures and require skill to determine P-PO4 3-with both high accuracy and precision.…”

Section: Introductionmentioning

confidence: 99%

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

2001

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Extensive studies have been devoted to the determination of phosphorus as phosphate ion by the molybdenum blue method. There have been many reports on various modifications of this method in order to make the sensitivity and stability high. Various reductants, such as 1-amino-2-naphthol-4-sulfonic acid, stannous chloride(II), and ascorbic acid have been used to reduce the molybdophosphate complex. 1-11 However, it is known to be difficult for methods using 1-amino-2-naphthol-4-sulfonic acid and stannous chloride(II) to control both the pH and the temperature. 12 It is also well known that solvent extraction with ethyl acetate, 1-butylalcohol, 2-methyl-1-propylalcohol, and so on, makes the sensitivity high. 5,[13][14][15][16][17][18][19][20][21] Motomizu et al. reported that the formation of colored ionassociate between molybdophosphate and Malachite Green could be utilized to determine phosphorus in the ultra-trace range from 0.018 to 1.0 ng cm -3 . 22These highly sensitive methods contain a few careful procedures and require skill to determine P-PO4 3-with both high accuracy and precision. Molybdenum blue methods containing other metal ions, such as Sb(III), so-called phosphoantimonylmolybdenum blue method, has also usually been used as manual batch procedures. 2,3,23 Blomqvist and Westin reported in detail the effect of Cr(VI), Ge(VI), W(VI), and V(V) ions that have easily reacted with heteropolyoxometalate on the absorbance measurement in the phosphoantimonylmolybdenum blue method. 24 Various flowinjection analysis methods, that analyze phosphorus automatically, have also been developed. 2,3,25 It was also reported that organic phophorus and hydrolyzable phosphorus were converted into the orthophosphate ion for determining P-PO4 3-. 3,4,[25][26][27] In a previous report, the formation conditions of molybdophosphate and -arsenate complexes in aqueous solution were confirmed. 28 A few kinds of molybdophosphate complexes have been formed under high acidic conditions. The addition of water-miscible organic solvents, such as acetonitrile and acetone, made only 12-molybdophosphate stable. Maeda et al. examined the electrochemistry of 12-molybdophosphate in aqueous-organic solution. 29 The reduced form of 12-molybdophosphate was found to be more stable in aqueousorganic solution than in aqueous solution. Based on these results, optimizing the formation conditions of the reduced 12-molybdophosphate complex in aqueous-organic solution seems to enable one to determine a wider range of concentrations of P-PO4 3-than the phosphoantimonylmolybdenum blue method as a manual batch procedure. ExperimentalThe absorption spectra were recorded on a Hitachi Model U-2000 spectrophotometer using silica cells with path lengths of 0.1 and 1 cm. Spectroscopic measurements under various conditions were made at 25 ± 0.1˚C without any baseline correction; those under the optimum determining conditions were made at room temperature. All of the reagents were of analytical grade, and were used as received. Results and Discussion Optimizatio...

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Section: Introductionmentioning

confidence: 99%

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

2001

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“…The conditions for the formation of arsenomolybdate 6 are similar to those reported by Wadelin and Mellon, 8 except that sulfuric acid is used in place of hydrochloric acid.…”

Section: Formation and Collection Of Arsenomolybdatementioning

confidence: 61%

Membrane solubilization with tetramethylammonium hydroxide for the preconcentration and electrothermal atomic absorption spectrometric determination of trace amounts of arsenic in water

Hata¹,

Yamada²,

Kasahara³

et al. 1999

Analyst

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“…A modification of the procedure of Akkseev ( 7) is described by Wadelin and Mellon (9) for the removal of phosphorus prior to determining arsenic. Sodium molybdate in hydrochloric acid is added to a solution containing phosphate and arsenate ions to form the respective molybdic acids.…”

Section: Herbicide Residuesmentioning

confidence: 99%

Herbicide Residues, Determination of Small Amounts of Arsenic in Potatoes: Extraction and Reduction of Molybdoarsenic Acid

Lisk¹

1960

J. Agric. Food Chem.

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Section 4: optical methods. Ultra-violet absorptiometric determination of arsenic as 12-molybdoarsenic acid

Cited by 23 publications

References 0 publications

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

Determination of Phosphorus Based on the Formation of a Reduced Keggin-Type 12-Molybdophosphate Complex in an Aqueous-Organic Solution

Membrane solubilization with tetramethylammonium hydroxide for the preconcentration and electrothermal atomic absorption spectrometric determination of trace amounts of arsenic in water

Herbicide Residues, Determination of Small Amounts of Arsenic in Potatoes: Extraction and Reduction of Molybdoarsenic Acid

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