Fluorescence spectroscopy, molybdenum

Monien et al. [515] have compared results obtained in the determination of molybdenum in seawater by three methods based on inverse voltammetry, atomic absorption spectrometry, and X-ray fluorescence spectroscopy. Only the inverse voltammetric method can be applied without prior concentration of molybdenum in the sample, and a sample volume of only 10 ml is adequate. Results of determinations by all three methods on water samples from the Baltic Sea are reported, indicating their relative advantages with respect to reliability. 

Laser Fluorescence Spectroscopy of Molecular Molybdenum Isolated in Rare Gas Matrices... 

Gravimetric methods and chemical methods, such as colorimetric measurements based on the arsenic-molybdenum blue complex (1,2,3) and arsine generation in combination with silver diethyldithiocarbamate (4, 5, 6,7), have been used to measure arsenic in aqueous media. Various instrumental methods such as differential pulse polarography (8), heated vaporization atomic absorption (9), arsine generation in combination with atomic absorption spectroscopy (10, 11, 12) or non-dispersive atomic fluorescence spectroscopy (13), and optical emission spectroscopy (14) can be used to determine arsenic in aqueous solutions. 

Numerous methods for determining macro concentrations of molybdenum are available. Optical emission spectroscopy has been used in survey-type analyses (2), but it does not have adequate sensitivity to measure part-per-billion levels. X-ray fluorescence has been applied for part-per-million levels but cannot be readily extended to the lower levels of interest to the Project. Kinetic methods (3) and colorimetry with suitable pre-concentration (4) are capable of measuring part-per-billion levels of molybdenum but have not been applied to petroleum analysis. Molybdenum has been determined by atomic absorption techniques in such materials as sea water, biological tissue, and soils (5,6,7), Although a procedure for determining metals including molybdenum in petroleum by atomic absorption has been reported (8), no actual data are given for molybdenum. Flame and heated vaporization atomic absorption of aqueous solutions of ashed samples were selected by the Project for concurrent study in two separate laboratories. 

---