pH-Metric method for acid number determination in hydraulic oils without titration.

A heptane-mediated extraction of acids from hydraulic oils is proposed for pH-metric acid number determination without titration. The acids are extracted in the reagent consisting of triethanolamine and potassium nitrate dissolved in water and isopropanol. The use of heptane allows us to overcome the influence of additives in the hydraulic oil on the glass electrode.

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.

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.

Microcell for anodic stripping voltammetry of trace metals.

A microcell for batch injection stripping voltammetry of trace metals with the use of a rotating disk working electrode has been developed and tested for samples of 0.2-0.3 mL.