METHOD OF DETERMINING CITRIC ACID AND CITRATES IN PROCESS FLUIDS CONTAMINATED WITH OIL PRODUCTS Russian patent published in 2024 - IPC G01N33/00 G01N33/84 

FIELD: measuring; chemistry.

SUBSTANCE: invention relates to a method for evaluating composition of process fluids. Method of determining concentration of citric acid and citrates in technical liquids based on ethylene glycol, contaminated with oil products, is characterized by that 100 ml of a sample of technical solution is separated, 20 ml is separated and several drops of concentrated hydrochloric acid, which do not contain iron ions, are added to pH = 2 and the concentration of iron ions is determined, then 80 ml of an unpreserved sample is placed in a separating funnel, extracted 3 times with 15 ml of hexane, lower layer is separated, 2 ml is collected and placed in a reaction flask, 2 ml of distilled water, 0.5 ml of 30 vol.% H₂SO₄, 0.5 ml of solution of 30 wt.% KBr and 1 ml of solution of 2.5 wt.% KMnO₄ are successively added, obtained mixture is shaken for 30 seconds and left for 5 minutes for oxidative bromination reaction, at the end of reaction 1 ml of a reducing agent is added to the mixture – solution of 5 wt.% ascorbic acid, turbidity of the obtained solution is determined on a spectrophotometer, at wavelength of 550 nm against a blank solution, a calibration curve is plotted in the concentration range from 0 to 5 g/l of citric acid in solution of 50 vol.% ethylene glycol with addition of iron ions in the concentration obtained at the first stage, and concentration of citric acid and citrates in the sample is determined.

EFFECT: invention enables to take into account the content of iron in the analysed solution, as well as determine the concentration of citric acid and citrates in the analysed sample.

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