ASTM D1840 Test Method for Naphthalene Hydrocarbons in Aviation Turbine Fuels
ASTM D1840 Standard Test Method for Naphthalene Hydrocarbons in Aviation Turbine Fuels by Ultraviolet Spectrophotometry
11. Procedure B - Alternative 100-mL Dilution
11.1 Discussion - The incorporation of the single dilution procedure has been included as an alternative procedure to reduce: test time, glassware, cleaning, and dilution errors.
11.2 For recommended techniques, refer to Practices E 169. Check carefully sections on handling and cleaning of cells and glassware, instrument adjustments, and method of absorbance measurement.
11.3 Sample Preparation - Add an appropriate weight of sample to a clean, dry, tared 100-mL volumetric flask. Record the weight to the nearest 0.0001 g. Dilute to the mark with spectroscopic grade isooctane, stopper and mix thoroughly.
11.3.1 Refer to Table 2 for lists of sample weights associated with naphthalene(s) concentrations that give 0.2 to 0.8 absorbance readings as directed in Note 7. A 60-mg sample will be appropriate for typical jet fuels in the range of 0.8 to 3.0 % volume naphthalenes.
NOTE 6 - A micropipette is a convenient tool for adding an appropriate volume. If the fuel density is not known at the time of sample preparation, use 0.8 as an approximation.
11.4 Measurement of Absorbance - Proceed as written in 10.3.
11.5 Determination of Cell Correction - Proceed as written in 10.4.
