Norimasa Yoza

Flow injection analysis of inorganic polyphosphates

Abstract Flow injection analysis is applied to the determination of orthophosphate and polyphosphates, such as diphosphate and triphosphate. A strongly acidic solution containing molybdenum(V) and molybdenum(VI) is used as the carrier so that hydrolysis of polyphosphates and color development of the resultant orthophosphate can be achieved simultaneously. For complete chemical reaction, the temperature of the reaction coil is maintained at 140° C. Application of a back-pressure coil is then necessary to eliminate the noise caused by gas bubbles. Total amounts of inorganic polyphosphates can be determined at a sampling rate of 45 samples per hour with a relative standard deviation of less than 1%. In addition, the flow injection system is shown to be useful as a post-column detector for high-performance liquid chromatography of inorganic polyphosphates. The efficiency of this system is compared with that of an air-segmented flow system.

Effect of column temperature on high-performance liquid chromatographic behaviour of inorganic polyphosphates : I. Isocratic ion-exchange chromatography

Abstract The isocratic elution conditions, column temperature and eluent concentration, at pH 10 for the analysis of inorganic polyphosphates were optimized to minize analysis time and to maximize resolution. The retention time was described as a function of eluent concentration. The column temperature affected drastically both the retention time and the band broadening of polyphosphates. The enthalpy change associated with the retention was calculated to be positive. A computer-assisted retention prediction system based on these relationships was successfully applied to the optimization of the elution conditions. The graphical presentation of the optimal elution conditions provided a simple technique for obtaining an adequate set data on the column temperature and eluent concentration for the complete separation and rapid analysis of inorganic polyphosphates.

Flow injection system as a post-column reaction detector for high-performance liquid chromatography of phosphinate, phosphonate and orthophosphate

Abstract A flow injection system was developed for the rapid flow analysis of lower oxo acids of phosphorus, such as phosphinate and phosphonate. A sodium hydrogen sulphite solution was used as an oxidizing agent for phosphinate and phosphonate, and a strongly acidic solution containing molybdenum(V) and molybdenum(VI) was used as a colour-forming reagent for the resultant orthophosphate. Lower oxo acids of phosphorus can be determined at a sampling rate of 60 samples per h with a relative standard deviation of less than 1%. The flow injection system was found to be useful as a post-column reaction detector for high-performance liquid chromatography of lower oxo acids phosphorus and orthophosphate.

Characterization of enzymatic hydrolysis of inorganic polyphosphates by flow injection analysis and high-performance liquid chromatography

Abstract A flow injection system using a molybdenum(VI) reagent and a high-performance liquid chromatographic system using a molybdenum(V)-molybdenum(VI) reagent were designed to characterize the substrate specificity and the metal ion specificity in the hydrolysis of polyphosphates by inorganic pyrophosphatase (EC 3.6. 1.1). The rapid reaction with a half-life of the order of 2 min was easily measured. The enzyme was quite specific for inorganic pyrophosphate of the ten polyphosphates tested at pH 7.2 and 30°C in the presence of magnesium ion. Magnesium ion activated the enzymatic reaction, while calcium and strontium ions inhibited the effect of magnesium ion.

Gel and ion-exchange chromatographic purification of the reaction products between diphosphate and diphosphonate

Abstract Gel and ion-exchange chromatographic techniques were applied to the separation of lower oxo acids of phosphorus, and , produced by the substitution reaction between (diphosphonate) and (diphosphate). Sephadex G-25 and Bio-Rad AG1-X8 columns were used. Hydrolysis of in the process of preparative separation is also discussed.

The Application of Atomic Absorption Method as a Flow Detector to Gel Chromatography

Abstract The applicability of atomic absorption method as a flow detector to gel chromatography was discussed. The effluent from the outlet of a Sephadex G-15 column was directly introduced into a nebulizer of atomic absorption spectrometer. It was found that the atomic absorption flow detector was sensitive and highly selective so as to permit the quantitative determination of metal ions. Some advantageous aspects of this detector were also discussed.

Gel chromatographic behavior of the oxo acids of phosphorus

Abstract A number of oxo anions of phosphorus which contain one to four phosphorus atoms in the molecule were eluted with potassium chloride solutions on Sephadex columns. The Kd values of the oxo anions of phosphorus were measured as functions of the concentration and pH of the eluents, sample concentration and gel prosoity. Kd values obtained by both the column and batch method were compared to each other. The main conclusions are as follows. (1) When pure water was used as an eluent, extremely low Kd values were observed because of the electrostatic repulsion between the sample anions and the negatively charged gel matrix. (2) The Kd values increased with increasing concentration of potassium chloride. This may be due to the variation in the degree of hydration of sample anions. (3) At sample concentrations lower than 10−2 gram atom P per 1 the elution curves were symmetrical, while unsymmetrical elution curves were obtained at the higher sample concentrations. (4) The Kd values did not depend on the pH values of the eluent. (5) The most satisfactory separation of ortho-, di- and triphosphate anions was carried out on a Sephadex G-25 column. (6) The effective sizes of the oxo anions of phosphorus in aqueous solution were stimated from the gel chromatographic data.

Gel chromatographic behavior of some metal ions

Abstract Some metal ions were chromatographed on Sephadex G-15 columns. Solutions of potassium chloride, sodium sulfate, sodium nitrate, and sodium perchlorate were used as eluting agents, i.e., as background electrolytes. It was found that the elution volumes of the metal ions depend very much on the nature of the background electrolytes employed. These phenomena were explained in terms of the penetrating ability of the background electrolytes into the gel phase and direct and indirect interaction between the metal ions and the gel matrix.

Chromatographic behavior of alkaline earth metal ions on sephadex G-15 columns

Abstract Alkaline earth metal ions were chromatographed on Sephadex G-15 columns with two different eluents, viz. , a 0.1 M sodium chloride solution and a 0.1 M sodium chloride—0.01 M hydrochloric acid solution. Separation of barium ions from the other alkaline earth metal ions was almost complete. The peak skewing of the elution curves of the alkaline earth metal ions, excepting magnesium, was ascribed to two factors: (1) the multicomponent character of the metal ions in solution and (2) the polyfunctional character of the gel phase due to incomplete penetrating ability of the background electrolyte into an inner part of the gel phase. Elution order could be explained in terms of the different sizes of the hydrated metal ions.

Gel chromatographic behavior of linear phosphates

Abstract Linear phosphates with degrees of polymerization of 1 to 13 were chromatographed on a Sephadex G-25 column with a 0.1 M potassium chloride solution and the following results were obtained. (1) The K av values of the linear phosphates did not depend on pH of the eluents. (2) A linear relationship was observed between the K av values and the logarithms of the degrees of polymerization. (3) Average degrees of polymerization of polyphosphate fractions determined by pH titration agreed approximately with those calculated from the gel chromatographic data.