ASTM D5291 Instrumental Determination of Carbon, Hydrogen, and Nitrogen
ASTM D5291 Standard Test Methods for Instrumental Determination of Carbon, Hydrogen, and Nitrogen in Petroleum Products and Lubricants
8. Preparation of Apparatus
8.1 Prepare the instrumental system (in its entirety) in strict accordance to the manufacturer's instructions.
8.2 Calibrate the system using acetanilide or other suitable calibration standard mentioned in Table 1, using the standardization procedure specified by the manufacturer. This procedure, with respect to the actual analytical process involved, must not differ from that specified for the samples.
8.3 Tubes/Columns Preparation (see Note 2) - Clean all quartz and glass parts prior to use with soap and water followed by acetone, and dry fingerprints must be removed with a grease solvent such as acetone, prior to insertion of the tubes into the furnace. Handle the tubes using appropriate gloves, such as lint-free cotton gloves, that will not leave fingerprints.
NOTE 2 - All combustion tubes and absorption tubes need to be periodically replaced after 50 to 300 sample runs. The exact intervals of change should be determined as recommended by the manufacturer.
8.3.1 Test Method A:
8.3.1.1 Combustion Tube - Pack 5 cm of quartz wool in the bottom of the tube on the primary (inlet) side. Set a ceramic crucible on top of the quartz wool on the primary side. Pack 3.1 cm of quartz wool in the bottom of the tube on the secondary (outlet) side. Fill 6.3 cm of furnace reagent on top of the quartz wool. Pack 11.9 cm of quartz wool on top of the furnace reagent.
8.3.1.2 Reduction Tube - Insert a small copper plug in the bottom. Fill up to 8.8 cm of N-catalyst on top of the copper plug. Add 13.8 cm of copper turnings on top of the N-catalyst.
8.3.2 Test Method B:
8.3.2.1 Combustion Tube - Precondition EA 1000 and silver tungstate on magnesium oxide by preheating it at 900°C for 10 to 30 min. Roll a strip of silver gauze to fit into the combustion tube. Clean the rolled gauze by either ultrasonically washing it in detergent and water, and drying it, or by passing it rapidly over a flame several times until the smoke disappears. Slide 2.5 cm of quartz wool into the tube from the outlet so that the end of the wool meets with the indentations in the tube. Add 5 cm of EA 1000 reagent. Top with a small wad of quartz wool. Add 5 cm of silver tungstate on magnesium oxide. Top with a small wad of quartz wool. Add 2.5 cm of silver vanadate. Top with a small wad of quartz wool. Slide a roll of silver gauze into the combustion tube, so that there is about 1.2 cm empty space left in the tube. Insert 1.2 cm of quartz wool into the inlet end of the combustion tube, and another into the vial receptacle, and place the receptacle into the combustion tube.
8.3.2.2 Reduction Tube - Insert a small wad of quartz wool into the inlet end of the tube to where the tube widens. Then insert a conditioned roll of silver gauze. Fill the tube from the outlet end. Fill with copper powder, occasionally tapping till the copper column is 23.8 cm deep. Insert a small wad of quartz wool, then add 1.2 cm of cuprox (copper oxide), and add another small wad of quartz wool. Insert the copper plug into the outlet end of the reduction tube.
8.3.3 Test Method C:
8.3.3.1 Combustion Reactor - First place a 2 mm plug of quartz wool in the bottom of the tube. Fill the tube with 50 mm of silver coated cobalt oxide. Insert a 10 mm thick plug of quartz wool. Add 120 mm of chromic oxide. Inset a 10 mm thick plug of quartz wool. Slide the combustion tube into the combustion furnace and secure with the o-ring fittings.
8.3.3.2 Reduction Reactor - First place a 5 mm plug of quartz wool in the bottom of the tube. Fill the tube with reduced copper. Insert a 10 mm thick plug of quartz wool. Slide the reduction tube into the reduction furnace and secure with the o-ring fittings.
8.3.3.3 Water Trap - First place a 10 mm plug of quartz wool in the bottom of the tube. Fill the tube with 3A 1/16 in. (1.6 mm) molecular sieve or magnesium perchlorate. Insert a 10 mm thick plug of quartz wool. Secure the tube in the water trap bracket.
8.3.3.4 Carbon Dioxide Trap - First place a 10 mm plug of quartz wool in the bottom of the tube. Fill the tube with 50 mm of magnesium perchlorate. Add 130 mm of sodium hydroxide coated silica. Add 50 mm of magnesium perchlorate. Insert a 10 mm thick plug of quartz wool. Secure the tube in the carbon dioxide trap bracket.
