Y. Krishna Reddy

Precipitation of zinc ammonium phosphate from homogeneous solution.

Urea hydrolysis has been employed to raise the pH for homogeneous precipitation of zinc ammonium phosphate. From 30 to 100 mg of zinc can conveniently be determined by this technique (relative standard deviation 0.2% for 89 mg). The interference of nickel was minimized by using ammonium tartrate as masking agent, but copper could not be effectively masked with the same tartrate. Ammonium tartrate obtained from a different source was found to mask the copper more effectively. Investigations showed that the latter tartrate contained an appreciable amount of ammonium oxalate.

Amperometric determination of copper with resacetophenone-phenylhydrazone

An amperometric method for determination of copper (II) with resacetophenone-phenylhydrazone is described. The method is useful to determine the metal in amounts ranging from 1·0–16·0 mg with an accuracy of ±1 per cent. Ten-fold excess of zinc, cadmium and nickel did not interfere. Iron which interefered both polarographically and chemically was complexed with sodium fluoride and the determination was successfully carried out. The method was applied for the determination of the metal in german silver.

Simultaneous amperometric determination of nickel and copper.

A method is described for the amperometric titration of nickel and successive amperometric determination of copper and nickel. Nickel (1.0-16.0 mg) and copper (1.0-11.0 mg) could be determined with an average error of less than 1%. Cobalt interferes but chloride does not. Interference by aluminium, iron(III) and chromium can be eliminated. Zinc and manganese do not interfere if the correct applied voltage is chosen. The procedures can be utilized in the analysis of alloys such as nichrome, Raney nickel, constantan, german silver and manganin. It is best to use the standard addition method for less than 3 mg of nickel.

Kinetic-spectrophotometric determination of manganese

A simple and fairly selective kinetic method has been developed for the determination of manganese(II) based on its catalytic activity on the autoxidation ofo-hydroxyphenylthiourea (ohptu). It is found that the rate of the reaction is proportional to the concentration of manganese(II) ions. The reaction is carried out in a borate buffer of pH 7.5 and determined effectively in the range of 0.05–0.50 μg of manganese per ml. The methods of tangents and of fixed time are employed. The former method is more accurate than the latter. The present method has been applied to foodstuff like cabbage, tomato and potato wherein manganese plays a vital role in various physiological functions. Many associated metal ions do not interfere in the determination.

Precipitation of bismuth quinolin-8-olate from homogeneous solution by urea hydrolysis

The precipitation of bismuth quinolin-8-olate by the conventional method could not be employed for the gravimetric determination of the metal owing to uncertainty of its stability at higher temperatures. These difficulties were overcome by precipitating bismuth quinolin-8-olate from homogeneous solution utilising urea hydrolysis to increase the pH of the acidic solution in the presence of sodium acetate. Results obtained from gravimetric and thermogravimetric measurements showed that the precipitate could be weighed as the monohydrate after drying at 105 °C, as the anhydrous complex after drying at 150 °C or as an oxide after ignition of the complex above 540 °C.

Titrimetric determination of dissolved oxygen in waste water

Winklers procedure for the determination of dissolved oxygen has been modified to cope with substantial amounts of oxidizing or reducing substances in the samples. The manganese(III) is treated with an excess of hydroquinone, the unconsumed part of which is then titrated with standard ceric sulphate solution. A blank determination is also carried out, in which the order of addition of reagents is reversed so that the solution is always acidic, to allow for the interfering substances present. Results obtained by using this modified procedure on clean samples are in good agreement with results obtained by the usual Winkler method.

Amperometric determination of palladium

Palladium (II) can be determined within + 0.5% in presence of nickel by amperometric titration with resacetophenone oxime either by (i) adding an excess of the oxime and titrating the excess with copper (II) in sodium acetate-acetic acid buffer; or by (ii) a direct titration using chloroform to prevent the palladium complex coming in contact with the mercury pool. However, this method cannot be adopted for the simultaneous determination of Pd and Ni.

GALLACETOPHENONE OXIME AS A REAGENT FOR GRAVIMETRIC DETERMINATION OF COPPER AND ITS SEPARATION FROM OTHER ELEMENTS.

ConclusionGallacetophenone oxime is a more useful analytical reagent for the determination of copper in presence of nickel, cadmium, zinc, manganese, selenium and iron than either salicylaldioxime or resacetophenone oxime. It is more soluble in water and its gravimetric factor (0.1486) is more favourable than with either salicylaldioxime (0.1895) or resacetophenone oxime (0.1607).

Amperometric estimation of copper with resacetophenone-oxime

The amperometric estimation of copper with resacetophenone-oxime was carried out by titration in 10% aqueous alcoholic medium at pH 4·8 and an applied voltage of − 0·60V (vs. merucry pool anode). Results within ± 1% error were obtained for amounts ranging from 2·0 to 10·0 mg. and as much as five times its weight of cadmium or nickel did not interfere.