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US 8,557,589 B2Granted
Method for quantitatively determining the dye content in dyed oils
AssigneeUnited Technologies Corporation
InventorsHolly S. Eccleston, Mimi Nguyen-Vu, Philip H. Ratliff
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Abstract
A new method to determine by quantitative analysis the amount of dye present in dyed engine oils is provided. The method uses imaging techniques, such as spectrophotometry, and a combination of dilution and standard addition techniques to quantitatively determine the concentration of dye in the engine oil to ascertain whether dye concentrations in engine oil have decreased as compared with original specifications, and to quantify the amount of dye to be added to the dyed engine oil to bring dye concentrations to original concentrations.
Claims25
A method for quantitative analysis of engine oil having an unknown concentration of dye, the method comprising:
- preparing a diluted test sample by diluting a test sample of the engine oil with a non-reactive solvent, and calculating the dilution factor by the formula:
- dilution factor of test sample equals Total Mass of diluted test sample (grams) divided by mass of original test sample (grams);
- preparing a stock solution by adding a known weight of dye to a known weight of new engine oil;
- preparing two or more standard solutions by adding incrementally-increasing weights of said stock solution to said diluted test sample;
- measuring absorbance values of said two or more standard solutions by spectrophotometry;
- measuring by spectrophotometry the absorbance values of the diluted test sample;
- determining the concentration of the dye in the test sample based upon the measured values of said two or more standard solutions and the concentrations of dye added;
- and
- comparing the concentration of dye in the test sample with a desired concentration of dye in the engine oil to quantify the amount of dye to be added to said engine oil to bring the dye concentration to the desired concentration.
6 more elements
A method to determine dye content of an engine oil having an unknown amount of dye, the method comprising:
- preparing a stock solution by taking a known amount of dye and diluting it approximately 100-fold with a known weight of new engine oil, and calculating the concentration of the stock solution by the equation:
- [concentration of stock solution, parts per million (ppm)]=(mass of dye, grams (g)÷mass of new engine oil, g)*106 ppm;
- preparing a diluted test sample by diluting a test sample of the engine oil between eight-fold and twelve-fold with a non-reactive solvent of similar polarity to said dyed engine oil, and wherein a dilution factor may be calculated by the equation:
- dilution factor of test sample equals Total Mass of diluted test sample (grams) divided by mass of original test sample (grams);
- preparing two or more standard solutions of said engine oil, wherein the two or more standard solutions contain incrementally-increasing weights of the stock solution which are then diluted to the same final weight by addition of said diluted test sample, and the actual concentration of each standard solution calculated by the equation:
- mass of stock solution (grams)*[concentration of stock solution, ppm]÷mass of diluted test sample, (grams);
- measuring by spectrophotometry the absorbance values of each of said two or more standard solutions at the pre-selected peak wavelength;
- plotting the maximum measured absorbance values of said standard solutions versus concentrations of dye added in said standard solutions;
- plotting a best-fit line or calculating the equation of a best-fit line by linear regression analysis through the data points corresponding to said two or more standard solutions, wherein the best-fit line is expressed as an equation of the form y=mx+b, where x is said concentration of the dye in the standard solution, y is said absorbance value, m is the slope of said best-fit line, and b is the y-axis intercept corresponding to a standard solution with zero dye added;
- calculating the concentration of the dye in said test sample as the slope m of said intercept b, and the concentration of dye in the engine oil is calculated by:
- [concentration of dye]=b÷m*dilution factor;
- and
- calculating a mass and volume of dye to be added to the engine oil to bring the concentration of dye in said dyed engine oil within a desired dye concentrations by the following equations:
- A=amount of dye to be added=desired concentration of dye in dyed engine oil (approximately 150 ppm)−present calculated concentration of dye;
- B=mass of 1 gallon of oil=3766 grams;
- C=mass of dye to add (grams)=B times A divided by 106 (parts per million);
- and
- D=amount of dye in milliliters (mL) to add per gallon of oil=C÷0.96 (g/mL), wherein the density of the oil is 0.96 g/mL.
15 more elements
Dependencies are inferred from the claim text.