Studies on some heteropoly blues—I the reduction of 12-molybdophosphoric acid with stannous chloride

El-Shamy, H. K.; Iskander, Magdi F.

doi:10.1016/0022-1902(73)80195-2

Cited by 7 publications

(10 citation statements)

References 14 publications

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“…At a given acid concentration, the amount of 12-MPA formation and reduction increases sharply with increasing Mo(VI) concentration, until a certain critical Mo(VI) concentration is reached. At this point, the further formation of PMB tapers off and the direct reduction of Mo(VI) to form isopolymolybdenum blues begins [40]. Thus, it can be seen that whilst the Mo(VI) concentration can be easily optimised for each acidity, sensitivity is quickly lost at higher acidities ( Fig.…”

Section: Spectral Features Of Pmbmentioning

confidence: 89%

“…Thus, if one attempts to simply dissolve solid 12-MPA in acid and reduce it without adding Mo(VI), very low apparent absorptivities will be obtained [40], as most of the 12-MPA will in fact decompose in accordance with its formation equilibria ( Fig. 3) [40,60]. Thus, sufficient Mo(VI) must be present to stabilise 12-MPA against hydrolytic decomposition.…”

Section: Spectral Features Of Pmbmentioning

confidence: 96%

“…The difficulty lies in the nature of MB chemistry as one complex equilibrium system; rather than stoichiometric reactions occurring, sufficient reagent must be introduced to perturb the equilibria to a desirable extent. Thus, if one attempts to simply dissolve solid 12-MPA in acid and reduce it without adding Mo(VI), very low apparent absorptivities will be obtained [40], as most of the 12-MPA will in fact decompose in accordance with its formation equilibria ( Fig. 3) [40,60].…”

Section: Spectral Features Of Pmbmentioning

confidence: 97%

“…The molar absorptivities of the strong IVCT bands are significantly higher for PMB(4e À ) than PMB(2e À ) [54,55,57], but excessive reduction yields PMB(6e À ) which immediately decomposes in acid [40,42,58]. This demonstrates that whilst a higher degree of reduction is desirable for improving analytical sensitivity, overwhelming reducing power should be avoided.…”

Section: Spectral Features Of Pmbmentioning

confidence: 97%

“…SnPMB(4e À ) may ultimately be hydrolysed to [H 4 PMo 12 O 40 ] 3À over time, although this process is accelerated with either heating [62,94] or further acidification [40], indicated by the emergence of the 820 nm peak (Fig. 6).…”

Section: Metallic Reductantsmentioning

confidence: 98%

See 4 more Smart Citations

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

Nagul

McKelvie

Worsfold

et al. 2015

Analytica Chimica Acta

321

247

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The molybdenum blue reaction, used predominantly for the determination of orthophosphate in environmental waters, has been perpetually modified and re-optimised over the years, but this important reaction in analytical chemistry is usually treated as something of a 'black box' in the analytical literature. A large number of papers describe a wide variety of reaction conditions and apparently different products (as determined by UV-visible spectroscopy) but a discussion of the chemistry underlying this behaviour is often addressed superficially or not at all. This review aims to rationalise the findings of the many 'optimised' molybdenum blue methods in the literature, mainly for environmental waters, in terms of the underlying polyoxometallate chemistry and offers suggestions for the further enhancement of this time-honoured analytical reaction.

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Section: Spectral Features Of Pmbmentioning

confidence: 89%

Section: Spectral Features Of Pmbmentioning

confidence: 96%

Section: Spectral Features Of Pmbmentioning

confidence: 97%

Section: Spectral Features Of Pmbmentioning

confidence: 97%

Section: Metallic Reductantsmentioning

confidence: 98%

See 3 more Smart Citations

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

Nagul

McKelvie

Worsfold

et al. 2015

Analytica Chimica Acta

321

247

View full text Add to dashboard Cite

show abstract

Heteropolyacids — new efficient initiators of cationic polymerization

et al. 1989

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929Heteropolyacidsnew efficient initiators of cationic polym e r i z a t i o n a ) Dedicated to Professor Paul Rempp on the occasion of his 60th birthday SUMMARYWe have found, that heteropolyacids (HPA) are efficient initiators of cationic polymerizations, including polymerizations of cyclic ethers and acetals, providing high-molecular-weight polymers. In several systems (e g. THF, 1,3dioxolane) the degree of polymerization is given by the ratio of concentrations of monomer and initiator, as for the living system. In the polymerization of cyclic formaldehyde trimer: 1,3,5-trioxane, the comparable polymerization rates may be obtained with 25 times less an initiator consumption on weight basis (= lo3 times less on molar basis) than for typical initiators like BF, . OR,.

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The nature of the salt error in the Sn(II)-reduced molybdenum blue reaction for determination of dissolved reactive phosphorus in saline waters

Nagul

McKelvie

Kolev

2015

Analytica Chimica Acta

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Studies on some heteropoly blues—I the reduction of 12-molybdophosphoric acid with stannous chloride

Cited by 7 publications

References 14 publications

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

Heteropolyacids — new efficient initiators of cationic polymerization

The nature of the salt error in the Sn(II)-reduced molybdenum blue reaction for determination of dissolved reactive phosphorus in saline waters

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