pH-Metric determination of acid numbers in petroleum oils without titration.

A new pH-metric method without titration has been developed for determination of acid numbers lower than 0.1 mg (KOH) g(-1) (oil) in petroleum oils such as White, Transformer and Basic oils. The method is based on rapid and complete extraction of acids from an oil test portion into the novel reagent and measurement of the conditional pH in the ;oil-reagent' mixture by a glass electrode.

Simultaneous voltammetric determination of uric and ascorbic acids in urine.

Anodic voltammetric method for simultaneous determination of uric acid (UA) and ascorbic acid (AA) in urine has been developed with the use of a commercial working rotating glassy carbon electrode. UA may be determined in a sample diluted by the buffer supporting electrolyte (HOAc+NH(4)OH; pH 5.1-5.

Corrosion behavior of PIRAC nitrided Ti-6Al-4V surgical alloy.

Hard titanium nitride (TiN) coatings were obtained on the surface of Ti-6Al-4V alloy using an original PIRAC nitriding method, based on annealing the samples under a low pressure of monatomic nitrogen created by selective diffusion of N from the atmosphere. PIRAC nitrided samples exhibited excellent corrosion resistance in Ringer's solution in both potentiodynamic and potentiostatic tests. The anodic current and metal ion release rate of PIRAC nitrided Ti-6Al-4V at the typical corrosion potential values were significantly lower than those of the untreated alloy.

pH-metric determination of acid numbers of petroleum oils without titration.

A pH-metric method was developed for determination of the acid numbers of oils containing organic and inorganic acids at levels <0.1 mg KOH/g oil. The method is based on rapid and complete extraction of acids from a test portion of oil into a special reagent, and measurement of the conditional pH of the mixture "oil-reagent" by a glass electrode.

Simultaneous determination of water and enediols or thiols in chemical products and drugs not amenable to direct Karl Fischer titration.

A method proposed for determining water and enediols or thiols is based on consecutive titration of the enediols or thiols by a novel reagent and of water by the conventional Karl Fischer reagent in the same cell. The time for both titrations is 8-20 min. The novel reagent consists of iodine, sodium acetate as a base, and potassium iodide in a nonaqueous solvent system.