ASTM D4045 Test Method for Sulfur in Petroleum Products
ASTM D4045 Standard Test Method for Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry
10. Procedure
10.1 Advance the tape and inject the unknown sample. After a stable reading is obtained record this average value as Rs in 11.1.
10.2 Proceed with additional samples. Every 2 h, or as needed, verify blank and span values.
10.3 To measure sulfur below 1 mg/L, inject the sample at the maximum rate, normally 6 µL/min, that does not form carbon or gums to obtain the best signal to noise ratio. Samples above 1 mg/L require proportionally lower injection rates or span adjustment. A sharp fall in response at high sulfur levels indicates color saturation of the tape, which can be prevented by slower injection rates.
11. Calculations and Report
11.1 Calculate the concentration of the sulfur in the sample as follows:
S, mg/L = Cstd x (Rs - Rb)/(Rstd - Rb)
where:
Cstd = concentration of sulfur in the standard, mg/L,
Rb = response for blank run using no sample or for solvent known to be sulfur-free,
Rs = response for unknown sample, and
Rstd = response for standard reference material.
11.2 Report mass of parts per million of sulfur as follows:
S, ppm = (mg/L)/(density) = mg/kg
since density of sample is in grams per cubic centimetres.
