Analytical application of the urease method for determination of urea in the presence of biuret.

Biuret does not interfere in the urease-catalysed hydrolysis of urea.

The effect of orthophosphate on the gravimetric determination of pyrophosphate.

The effect of orthophosphate on the precipitation of zinc pyrophosphate has been examined and it is shown that co-precipitation of the orthophosphate at pH 3.4-3.6 is serious if the orthophosphate concentration is >0.02M. Even with lower concentrations an error of up to +2% may occur.

Analytical applications of graphite electrode modified with Bis(diisopropyloxithiophosphon)Disulphide.

A modified graphite electrode was produced by adsorption the bis(diisopropyloxythiophosphone)disulphide {(i-PrO-)(2)P(S)S-}(2) under vacuum. Its electrochemical characteristics in flowing stream were described. The modified electrode has been used for simultaneous determination of Cu(II), Ag(I) by flow injection anodic stripping voltammetry.