EXPLANATION
These test methods cover the determination of lead in gasoline in the range of 0.0026 to 1.32 g lead/L. These test methods compensate for the normal variation in gasoline composition and are independent of lead alkyl type. Three parts of this test method had different designations earlier. Test Method A was formerly Methods ASTM D2599 Sections 5-9; Test Method B was ASTM D2599 Sections 10-14; and Test Method C was D3229 Sections 15-19.
TEST SUMMARY
Test Method A Bismuth Internal Standard Method for High Concentration - One volume of the sample is mixed with an equal volume of bismuth internal standard solution. The mixture is placed in an X-ray beam and radiations at 1.75 A for lead and 1.144 A for bismuth are measured. By comparing the ratio of intensities to that of known standards, the lead content of gasoline is calculated.
Test Method B Scattered Tungsten Radiation Method - The ratio of the net X-ray intensity of lead radiation to the net intensity of the incoherently scattered tungsten radiation is obtained on a portion of the sample. By comparing this to the intensity of a known lead standard, the lead content of gasoline is calculated.
Test Method C Bismuth Internal Standard Method for Low Concentration - This test method is the same as in Test Method A, but additionally a background radiation at 1.194 Å is also measured. A blank made with isooctane and bismuth internal standard is run using the same procedure. The lead content of gasoline is calculated based on comparing the ratio of lead to bismuth radiation intensities to that of known standards, after subtracting the blank ratio.
TEST PRECISION
Where X is the average result expressed in g lead/L at 15° C in Test Methods A and B, and in g lead/US gallon at 15.5° C in Test Method C.
These test methods have no bias.