Emission spectrometric methods of analysis

Determination of zirconium, molybdenum, hafnium, and tungsten in niobium and tantalum by x-ray fluorescence spectrometry after separation from matrix and preconcentration

“…Optical emission spectrography using a dc arc and involving the conversion of the metals into oxides before the analysis can detect these elements only at the 10 µg/g level (3,4). By addition of certain substances, e.g., AgCl and CdS in the determination of tungsten (5), or by separations (6), the limits of detection can be improved by about 1 order of magnitude.…”

“…Usually low levels of NAD+ are measured by an enzymatic cycling procedure which amplifies a small quantity of coenzyme. One previously described cycling procedure utilized alcohol dehydrogenase and malic dehydrogenase (7) and has been applied to immunoassay techniques (2)(3)(4). However, as pointed out by O'Sullivan (8), these methods are of poor practical interest due to interference from biological samples which affect the enzymatic cycling step and the final fluorimetric measurement.…”

“…a OES without matrix separation(3,4).b XRFS after extraction of matrix with MIBK and coprecipitation of Zr with Co(OH)3 (12). c Instrumental proton AA (14).…”

Radiochemical multielement neutron activation analysis of high-purity niobium with short-lived indicator radionuclides

“…1980, 52, 2403-2406. (14) Vogel, A. I., "A Textbook of Quantitative Inorganic Analysis"; 3rd ed. ; Longmans: London, 1961; p 35.…”

Nonferrous metallurgy. II. Zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten

“…Tungsten was determined in niobium metal and oxide by Brooks (65,66) who used both the powder-d.c. arc technique in which he mixed the sample with an equal weight of silver chloride and the fusion-d.c. arc technique in which the sample is fused with potassium pyrosulfate. Buyanov, Ivanova, and Sukhova (80) used either an arc or low voltage spark for the determination of tungsten in heat-resistant alloys with a quantometer.…”