a simple and rapid method has been developed for the determination of ascorbic acid in fruit and pharmaceutical products. the method is based on the measurement of the reaction rate between ammonium molybdate and ascorbic acid in acidic media. the reaction was monitored spectrophotometrically at 800 nm by fixed-time and variable-time methods. the calibration graph was linear in the range of 5 0...

The simultaneous spectrophotometric determination of phosphate and silicate ions in river water was examined by using ion-exclusion chromatography and post-column derivatization. Phosphate and silicate ions were separated by the ion-exclusion column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the H(+)-form (TSKgel Super IC-A/C) by using ultra pure water as an elu...

The range of inorganic acid normalities for maximum color formation of the phosphomolybdenum-blue complex (under heating) increases by elevating the ammonium molybdate concentra­ tion, and at a ratio of molybdate molarity/acid normality equal to 10, there is maximum color development at any acid normality in the range 1—4 n with either HC104 or H2S04 (or their mixtures). On the basis of these f...

A 1,10-phenanthroline (phen) chelated molybdenum(VI) citrate, [(MoO2)2O(H2cit)(phen)(H2O)2] x H2O (1) (H4cit = citric acid), is isolated from the reaction of citric acid, ammonium molybdate and phen in acidic media (pH 0.5-1.0). A citrato oxomolybdenum(V) complex, [(MoO)2O(H2cit)2(bpy)2] x 4H2O (2), is synthesized by the reduction of citrato molybdate with hydrazine hydrochloride in the presenc...

Hoher Terminund Budgetdruck, kürzere Entwicklungszeiten bei gleichzeitig komplexer werdenden Softwaresystemen, die zudem oft noch verteilt entwickelt werden: Die Anforderungen an die Entwicklung individueller Softwarelösungen steigen. Während auf die Optimierung von Prozessen in Entwicklungsprojekten bereits großer Wert gelegt wird, vernachlässigen viele Unternehmen die Produktqualität. Dabei m...

In microaerophilic or anaerobic environments, Pseudomonas aeruginosa utilizes nitrate reduction for energy production, a process dependent on the availability of the oxyanionic form of molybdenum, molybdate (MoO4 (2-)). Here, we show that molybdate acquisition in P. aeruginosa occurs via a high-affinity ATP-binding cassette permease (ModABC). ModA is a cluster D-III solute binding protein capab...

The great instability of creatine phosphate (Fiske & Subbarow, 1929), acetyl phosphate (Lipmann & Tuttle, 1944) and 1:3-diphosphoglyceric acid (Negelein & Bromel, 1939) in solutions containing molybdate has been known almost as long as these compounds themselves. It could not fail to attract the attention of the analyst who used a method of phosphate estimation ofthe Briggs (1922) or Fiske & Su...

Extracts of liver and muscle convert citric acid into laevo-rotatory isocitric acid [Martius, 1938]. As the rotation of isocitric acid, like that ofother ac-hydroxy acids, is much increased by (NH4)2MoO4*, the polarimeter can be used to measure low concentrations of isocitric acid in tissue extracts [Martius, 1938; Jacobsohn, 1940]. On applying this method to plant extracts we met with an unexp...

A sensitive solvent-free extraction protocol for the quantification of arsenic at trace level has been described. It is based on the reaction of arsenic (V) with molybdate in acidic medium in presence of antimony (III) and ascorbic acid as a reducing agent to form a blue-colored arsenomolybdenum blue complex. The complex has been extracted into surfactant phase using Triton X-114, and its absor...

Iron molybdate catalysts were prepared using a sol gel route with malonic acid and oxalic their performance for the selective oxidation of methanol to formaldehyde was evaluated.