Mechanisms of atomization of molybdenum in graphite furnace atomic absorption spectrometry

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy 1986, Vol.41 (7), p.651-667
• Main Authors: Wu, Shaole, Chakrabarti, C.L., Marcantonio, F., Headrick, K.L.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/0584-8547(86)80081-7

Mechanisms of atomization of molybdenum in graphite furnace atomic absorption spectrometry have been investigated using platform technique along with X-ray diffraction spectrometry, scanning electron micrography, energy dispersive X-ray and Auger electron spectrometry. Three molybdenum oxides: MoO 2(s), MoO 3(s) and Mo 4O 11(s), have been identified—all formed at relatively low temperatures (< 1500 K). Crystallites of MoO 2 of relatively large size are formed on the pyrolytic graphite surface. When molybdenum is atomized from a pyrolytic graphite surface, the charring curve of molybdenum shows a dip in absorbance in the temperature range 1200–1800 K. Hence, a charring temperature < 1200 K should be used for determination of molybdenum when a pyrolvtically coated graphite tube or a platform made of pyrolytic graphite is used. Mo s, MoC s and Mo 2C (s) have been found on both pyrolytic graphite and electrographite surfaces in the charring step. Formation of Mo g, by direct sublimation of Mo (s) and/or dissociation of MoC (g) are all spontaneous reactions at the temperatures considered.