EXPLANATION
This test method was developed to provide for the enforcement of 26 CFR 48.4082-1(b), which mandates that all tax exempt diesel fuels be dyed with an amount of solvent Red 164 at a concentration that is spectrally equivalent to 11.1 mg/L of Solvent Red 26. The test is used to verify that the correct amount of dye has been added at terminals, or refineries before sale. Solvent Red 26 is considered as a reference standard because it is available in certified pure form. On the other hand, composition of solvent Red 164 dye varies but it has higher solubility and is relatively less expensive.
TEST SUMMARY
The absorbance of each sample is recorded over a specified wavelength range, and the scan is analyzed using derivative analysis software to determine the dye concentration.
TEST PRECISION
Where X is the mean dye concentration in mg/L of two results.
The bias of this test method has not been determined.