Abstract: A reagent for pH-metric acid number determination in a petroleum oil with low acid numbers (AN≦0.03 mg KOH/g oil) includes a salt of a strong base and a weak acid, and, an alkali in a mixture of water and an alcohol. The salt of a strong base and a weak is, preferably, sodium benzoate in a concentration of 0.02 to 0.1 M. The alcohol is, preferably, isopropanol in a concentration of from 50% to 80% by volume. The alkali is, preferably, an hydroxide and, most preferably, potassium hydroxide. The alkali should be adjusted to provide a pH′o, which is the pH of an equivalence-point on a titration curve of a strong acid added to a test portion of sodium benzoate, water and isopropanol.

Abstract: A novel method for preparation of electrodes at a low temperature from electroconducting refractory powder materials. The electrodes are useful for analytical purposes. The method is based on cold pressing of the powders, wetted with solution of a polymer and placed into a disposable frame of the same polymer, with the help of a laboratory hand device producing a relatively small pressure. Control of the end of pressing is done by means of measurement of the electrode resistance. A puncheon serves as a current conductor. Electrodes thus prepared have a low resistance, a high sensitivity and stability. In comparison with glassy carbon electrodes, the most widely applied ones in electroanalytical chemistry, the novel electrodes are cheaper, yet not inferior to such glassy carbon electrodes, and even sometimes better.