Thermometric titration in investigation of the formation of polyanions of molybdenum(VI), tungsten(VI), vanadium(V), and chromium(VI). III. Titration of molybdic acid with sodium hydroxide solution
To define the propenties of molybdenum-containing species which appear in the acidification of neutral molybdate solution with mineral acid, the reverse process (i.e., the titration of molybdic acid of acidified molybdate solution with sodium hydroxide) was examined and the titration curves were obtained thermometrically as well as potentiometrically. In the thermometric titration curves there are inflections not found on the pH-titration curves of the same systems. Titration curves of both methods change with molybdenum concentration, the reaction process being found to be responsible for the change. Polymolybdate anions were identified with the aid of the ultraviolet spectrophotometry of Punger et al. A neutral salt such as sodium perchlorate or lithium perchlorate was found to affect the shape of the thermometric titration curve, since in the presence of such salt octamolybdate ion was readily converted into heptamolybdate ion. (auth) l5305 The adaptation of a tantalum filament vaporization system as sample introduction device for the inductively coupled plasma is described. The potential advantages of this analytical system for simultaneous multielement determinations of elements at the ng/ml level are discussed and a comparison of the plasma system with the filament techniques utilized in atomic absorption or fluorescence spectroscopy is presented. For one set of operating cnditions, detection limits for 16 elements were in the ng/ml to fractional ng/ml range for 100- mu l samples. Typical precision data and an analytical curve for the determination of Be in the range of 0.001 to l0 mu g/m1 are included. (auth)
- Research Organization:
- Nagoya Univ. (Japan)
- NSA Number:
- NSA-29-015304
- OSTI ID:
- 4345201
- Journal Information:
- Bull. Chem. Soc. Jap., v. 46, no. 10, pp. 3086-3090, Other Information: Orig. Receipt Date: 30-JUN-74; Bib. Info. Source: JA (JA)
- Country of Publication:
- Japan
- Language:
- English
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