COLORIMETRIC METHOD DETECTING PRESENCE OF DEPRESSANT ADDITIVES IN DIESEL FUELS Russian patent published in 2003 - IPC

FIELD: determination of chemical composition of diesel fuel with use of color indicator. SUBSTANCE: proposed method employs indicator which changes color depending on chemical composition of diesel fuel and helps to make decision on presence of depressant additives in diesel fuel. Invention can find use in oil and gas production, in production of diesel fuels of winter type carrying depressant additives, in making decision on utilization of such fuels in equipment operating under conditions of negative temperatures. To detect presence or absence of depressant additive in diesel fuel this fuel is in accordance with invention is added in proportion 2-5:1 with mixture of aqueous solution of copper ammoniate [Cu(NH₃)₄]Cl₂ and isopropyl alcohol taken in proportion 1:2-3. This mixture is stirred and cured at temperature 60-80 C in the course of 60-100 s. After phase separation presence of depressant additive is detected by appearance of yellow-green or green color of aqueous phase. Starting concentration of copper ammoniate is 150-200 mg/cu. dm in terms of copper. Observed change of color of aqueous phase takes place as result of process of complexing of components of depressant additive with heating of copper ammoniate. EFFECT: acceleration and simplification of method, increased reliability of detection of presence of depressant additives which as consequence reduces time of determination of fuel brand and of making decision on utilization of fuel. 4 tbl