Molybdenum determination

Taylor SR, McLennan SM (1985) The Continental Crust Its Composition and Evolution. Blackwell, Boston Tuit CB, Ravizza G (2003) The marine distribution of molybdenum. Geochim Cosmochim Acta 67 A4950 Tumlund JR, Keyes WR, Peiffer GL (1993) Isotope ratios of molybdenum determined by thermal ionization mass spectrometry for stable isotope studies of molybdenum metabolism in humans. Anal Chem 65 1717-1722... 

Quinolinol-Methyl isobutyl ketone solution, 0.5% for molybdenum determination Dissolve 0.5g of 8-quinolinol in 100ml of MIBK prepare fresh daily. 

The graphite furnace technique for atomic absorption spectrophotometry permits molybdenum determination at the ng level with small sample volumes. This technique is, however, prone to matrix interferences when used for molybdenum analysis. The boiling point of molybdenum is about 4600°C, about 1800°C above the maximum temperature obtained in the graphite furnace. Therefore, molybdenum atomization can only take place by a mechanism which includes the formation of a compound that is volatile at 2800°C. Molybdenum atoms will only be produced if the volatile molybdenum compound dissociates at this temperature. Any ions or compounds which affect the complicated atomization mechanism will alter the sensitivity of the method. This crucial fact is the primary reason for the extreme matrix sensivity of the method. 

Analytical Techniques for Molybdenum Determination in Plants and Soils... 

Clark, L. J., and Axley, J. H. (1955). Molybdenum determination in soils and rocks with dithiol. Anal. Chem. 27 2000-3. 

In this procedure (Soltanpour et al., 1982) the NH4HCO3 acts as both an extractant of Mo and a buffer, in a manner similar to the extraction of PO4. During extraction, the pH of the soil-AB-DTPA mixture increases to pH 8.5, dissolving calcium (Ca), aluminum (Al), and Fe molybdates (Soltanpour, 1991). Also, the HCO3- ions desorb molybdates from the surfaces of soil colloids. The DTPA may aid the Mo extraction process, but is included primarily for the extraction of multiple cations. Molybdenum determination is accomplished through use of inductively coupled plasma spectrometry (ICPS). The procedure has not been tested extensively on acid soils, but is outlined for use on alkaline or Mo-contaminated soils or spoils. 

Spectrophotometric determination of molybdenum can be accomplished by reaction with thiocyanate in an acid medium in the presence of tin(II) chloride (465 nm). Toluene-3,4-dithiol, usually referred to as dithiol, can also be used as a spectrophotometric reagent for molybdenum determination. In an acid medium, it forms a green complex that can be extracted using organic solvents. 

E. Fernandez and D. Prada, Multivariate optimisation for molybdenum determination in environmental solid samples by slurry extraction-ETAAS, Anal. Chim. Acta, 2005, 553, 208-213. 

USE In molybdenum determination by spectrophotometry [6964] in uranium determination by spectrophotometry [6965]. 

Figure 4.7 Matrix effect of humic substances the accuracy of molybdenum determination by IDMS and by external calibration with a standard solution. 1994 Springer-Verlag.

Schramel, P., and Wendler, I. (1995). Molybdenum determination in human serum (plasma) by ICP-MS coupled to a graphite furnace. Fresenius J. Anal. Chem. 351(6), 567. 

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