Spectrophotometric determination of phosphorus acid

Journal Article · Sun Mar 01 04:00:00 EST 1987 · Ind. Lab. (Engl. Transl.); (United States)

OSTI ID:6290535

Domin, A V; Domina, N G; Zakharov, Yu A; Shechkov, G T

A number of procedures have been proposed to determine phosphorus acid and its salts, the phosphites, in the presence of hypophosphorus acid and its salts, the hypophosphites. Among these procedures, iodometric back-titration has produced the most reliable results. In this paper, the authors propose an improved iodometric determination of phosphorus acid that enables the sensitivity to be increased by at least two orders of magnitude. The essence of this improvement is that excess iodine that did not react with phosphite ion is determined not volumetrically but spectrophotometrically. To eliminate the effect of iodine ion that is liberated when iodine reacts with phosphite ion on the optical density of the solution, a 200-fold excess of potassium iodide is added before the photometric measurement. The working iodine solution is prepared by diluting 10 m of 0.025 N iodine titrant and 50 ml of phosphate buffer, pH 6.7-7.2, to 1 liter with distilled water in a coulometric flask. To construct the calibration curve, 5, 10, 15, 20, and 25 ml, respectively of working iodine solution, and 10 ml of 2% aqueous potassium iodide are placed into five 100-ml volumetric flasks, and the solutions are made up to volume with water. After 10 min the photometric measurements are carried out at 380 nm using curvets and the reference solution is obtained by diluting 10 ml of 2% aqueous potassium iodide to 100 ml with distilled water.

• Research Organization: I.I. Polzunov Polytechnic Institute, Altai, USSR
• OSTI ID: 6290535
• Journal Information: Ind. Lab. (Engl. Transl.); (United States), Journal Name: Ind. Lab. (Engl. Transl.); (United States) Vol. 52:9; ISSN INDLA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
ACTIVATION ENERGY
ALKALI METAL COMPOUNDS
CALIBRATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DISPERSIONS
ELEMENTS
ENERGY
HALIDES
HALOGEN COMPOUNDS
HALOGENS
HYDROGEN COMPOUNDS
HYPOPHOSPHOROUS ACID
INORGANIC ACIDS
INORGANIC PHOSPHORS
INTERFERING ELEMENTS
IODIDES
IODINE
IODINE COMPOUNDS
IODOMETRY
KINETICS
MASS NUMBER
MATERIALS TESTING
MIXTURES
MOLECULAR WEIGHT
NONMETALS
OXIDATION
PHOSPHOROUS ACID
PHOSPHORS
PHOSPHORUS
POTASSIUM COMPOUNDS
POTASSIUM IODIDES
PROCESS SOLUTIONS
REACTION KINETICS
REAGENTS
SENSITIVITY
SOLUTIONS
SPECTROPHOTOMETRY
TESTING
TITRATION