Jiang Zhiliang

Catalytic spectrophotometric methods for the determination of oxalic acid

Abstract A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described, based on its catalytic effect on the redox reaction between dichromate and rhodamine B, measured at the maximum absorption wavelength of 555 nm in sulphuric acid. Under the optimum conditions of 0.05 mol l −1 H 2 SO 4 0.003 mol l −1 K 2 Cr 2 O 7 3.28 × 10 −6 mol l −1 rhodamine B at 90°C for 8 min, a calibration graph from 0.06 to 4 μg ml−1 oxalic acid and a detection limit of 20 ng ml−1 was obtained. No serious interferences were identified. Oxalic acid in spinach leaves and waste water was determined by this method, with satisfactory results.

Catalytic determination of ultratrace amounts of ruthenium with oscillopolarographic detection

The oscillopolarographic behaviour of Methyl Red in sodium hydroxide medium has been studied, and the results show that the wave at -0.79 V is an irreversible two-electron adsorption wave. A very sensitive and selective catalytic reaction-oscillopolarographic method for the determination of Ru down to 3 ng/l. is described, based on the Ru(III)-catalysed redox reaction of Methyl Red and potassium periodate in hydrochloric acid medium. Potassium thiocyanate is used to quench the reaction and the oscillopolarography is then performed with sodium hydroxide as the supporting electrolyte. The influence of 41 foreign ions has been examined. Ruthenium in ore samples has been determined by the method, with satisfactory results.

Polarographic determination of osmium with the osmium(VIII)-cerium(IV)-arsenic(III) system

A highly sensitive and novel polarographic method has been developed for determination of ultratrace amounts of osmium, based on the catalysis of the cerium(IV)-arsenic(III) reaction by osmium(VIII). The reaction rate is monitored by measuring the arsenic(III) with a single-sweep oscillopolarograph. Osmium concentrations from 7.0 x 10(-11) to 5.0 x 10(-9)M can be determined by the initial rate method. The method has been applied to determination of osmium in refined ore and chlorination residues with satisfactory results.

A novel and highly sensitive catalytic method with oscillopolarographic detection for the determination of ultratrace amounts of iridium

Iridium(IV) has a strong catalytic effect on the slow redox reaction between Malachite Green and periodate ion in pH 4.2 acetate buffer solution at 100 degrees , and Malachite Green exhibits a sensitive single-sweep oscillopolarographic wave at -0.65 V vs. SCE. This provides the basis for a novel and highly sensitive and selective catalytic method with oscillopolarographic detection for iridium. The effect of pH, potassium periodate and Malachite Green concentrations, reaction temperature and reaction time and other variables are investigated. The detection limit is 8 ng/l. with a fixed-reaction time of 10 min. A linear calibration graph from 24 to 1600 ng/l. is obtained. Possible interferences by co-existing ions are examined.

A new catalytic kinetic spectrophotometric method for determination of iron.

The catalytic effect of iron(III) on the oxidation of reduced Rhodamine B with hydrogen peroxide in acetic acid medium has been studied. The reaction is highly accelerated by potassium thiocyanate. A new catalytic kinetic spectrophotometric method for the determination of iron has been developed. Iron(III) can be determined by the fixed time method with a detection limit of 4 x 10(-11) g/ml.

Catalytic determination of ultratrace amounts of ruthenium with oscillopolarography monitoring

Abstract The single sweep oscillopolarographic behaviour of Rhodamine B in sulphuric acid medium was investigated. A novel, sensitive and selective catalytic method with oscillopolarography monitoring for the determination of ultratrace amounts of ruthenium was described, based on the catalytic effect of Ru(III) on the slow redox reaction occuring between Rhodamine B and potassium periodate in sulphuric acid medium at 25 °C. Single sweep oscillopolarography is used to monitor the changes in concentration of Rhodamine B by means of the second derivative wave at -0.55 V vs. SCE. The determination range from 8.2×10−10 to 2.5×10−8 M Ru was obtained by the initial rate procedure. Influence of 30 foreign ions was considered. Ru in ore samples was analysed by this method, with satisfactory results.

Catalytic kinetic determination of ultratrace amounts of nitrite with detection by linear scan voltammetry at a dme

Nitrite has a very strong catalytic effect on the bromate oxidation of Methyl Orange in dilute sulphuric acid medium. The oxidation product of methyl orange exhibits a well derivative voltammetric wave at -0.41 V vs. SCE in sodium hydroxide medium. The linear scan voltammetric behaviour for the product at a DME has been studied, and it was selected as indicator component for the indicator reaction. Based on these studies, a novel and highly sensitive and selective catalytic reaction-voltammetric method for nitrite is proposed. A detection limit of 2 x 10(-9)M and calibration graph from 4 x 10(-7) to 4 x 10(-7)M nitrite are obtained. Nitrite in water samples was determined by this method, with satisfactory results.

Catalytic method for the determination of traces of tungsten by linear scan voltammetry

Abstract A novel, sensitive and selective catalytic method for the determination of tungsten is described, based on the W(VI-catalysed redox reaction between methyl red and Ti(III) in a hydrochloric acid medium; methyl red exhibits a sensitive oscillopolarographic wave at −0.68 V vs. SCE in NaOH solution. A calibration graph from 3.2 to 72 ng ml −1 W (detection limit 1.1 ng ml −1 ) is obtained by the fixed-reaction time procedure. The influence of 29 foreign ions on the catalytic determination of W was examined; none interfered at