ASTM D3120 for trace quantities of sulfur in light liquid peroleum hydrocarbons
ASTM D3120 test method for Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry
13. Procedure
13.1 Obtain a test sample using the procedure described in Section 9. The sulfur concentration in the test sample shall be less than the concentration of the highest standard and greater than the concentration of the lowest standard used in the calibration. If required, a dilution should be performed on either a weight or volume basis.
13.1.1 Gravimetric Dilution, (mass/mass) - Record the mass of the test sample and the total mass of the sample and solvent.
13.1.2 Volumetric Dilution, (mass/volume) - Record the mass of the test sample and the total volume of the test sample and solvent.
13.2 Flush the sampling syringe several times with the unknown sample. Determine the sulfur concentration using one of the procedures described in 11.3 - 11.5.5.
13.3 Inspect the combustion tube and other flow path components to verify complete oxidation of the test sample.
13.3.1 Boat Inlet Systems - Reduce the boat drive introduction rate, sample size, or both, if coke or soot is observed on the exit end of the pyrolysis tube. Increase the residence time for the boat in the oxidation zone of the furnace if coke or soot is observed on the boat after the analysis is finished.
13.3.2 Syringe Inlet Systems - Reduce the sample size, rate of injection, or both, for the direct injection the test sample into the furnace if coke or soot is observed on the exit end of the pyrolysis tube.
13.3.3 Cleaning and Recalibration - Clean any coked or sooted parts per the manufacturer's instructions. Assemble and leak check the apparatus per the manufacturer's instructions after any cleaning or adjustment. Repeat instrument calibration prior to reanalysis of test samples.
13.4 To obtain one result measure each test sample solution three times and calculate the average value.
13.5 If the sample size is determined by volume, density values needed for calculations are to be measured (using Test Method D1298, Test Method D4052, or equivalent) at the temperature at which the sample was tested. If the sample size was determined by weight, density values are not required.
