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
5. Apparatus
5.1 Since a variety of instrumental components and configurations can be satisfactorily utilized for these test methods, no specifications are given here with respect to overall system design.
5.2 Functionally, however, the following are specified for all instruments:
5.2.1 The conditions for combustion of the sample must be such that (for the full range of applicable samples) the subject components are completely converted to carbon dioxide, water vapor (except for hydrogen associated with volatile halides and sulfur oxides), and nitrogen or nitrogen oxides. Generally, instrumental conditions that affect complete combustion include availability of the oxidant, temperature, and time.
5.2.2 Representative aliquots of the combustion gases must then be treated:
5.2.2.1 To liberate (as water vapor) hydrogen present as hydrogen halides and sulfur oxyacids, and
5.2.2.2 To reduce (to the element) nitrogen present as nitrogen oxides.
5.2.3 The water vapor and nitrogen so obtained must be included with the materials originally present in these aliquots.
5.2.4 Additional treatment of the aliquots (prior to detection) depends on the detection scheme utilized for the instrument (see Note 1).
NOTE 1 - These additional treatments can be provided by the instrumental components utilized to satisfy 5.2.2.
5.2.5 The detection system (in its full scope) must determine the analytical gases individually and without interference. Additionally, for each analyte, either:
5.2.5.1 The detectors must provide linear responses with respect to concentration over the full range of possible concentrations from the applicable samples, or
5.2.5.2 The system must include provisions for appropriately evaluating non-linear responses so that they can be accurately correlated with these concentrations.
5.2.6 Such provisions can be integral to the instrumentation, or they can be provided by (auxiliary) computation schemes.
5.2.7 Lastly, except for those systems where the concentration data are output directly, the instrument must include an appropriate readout device for the detector responses.
5.3 Additionally consumables needed for the analyses include:
5.3.1 Tin Capsules, large and small,
5.3.2 Ceramic Crucibles,
5.3.3 Copper Capsules,
5.3.4 Tin Plugs,
5.3.5 Tin Boats,
5.3.6 Copper Plugs,
5.3.7 Aluminum Capsules,
5.3.8 Combustion Tubes,
5.3.9 Adsorption Tubes,
5.3.10 Nickel Capsules, and
5.3.11 Reduction Tubes.
5.4 Analytical Balance, capable of weighing to the nearest 0.00001 g.
5.5 Syringes or Pipettes, to transfer the test specimens to capsules.
6. Reagents
6.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
6.2 Calibration Standards - Table 1 lists the pure organic compounds most commonly used to calibrate the instruments operated according to 3.4.1-3.4.3; other suitable pure compounds can also be used.
6.3 Carrier and Combustion Gases:
6.3.1 Oxygen, high purity (99.998 %),
6.3.2 Helium, high purity (99.995 %),
6.3.3 Compressed Air, Nitrogen, or Argon, for operating pneumatic valves, if needed, and
6.3.4 Carbon Dioxide.
6.4 Additional Reagents (as Specified by the Instrument Manufacturer) - This specification covers the reagents utilized to provide for the functional requirements cited in 5.2.2 and 5.2.3. These reagents can vary substantially for different instruments. Consequently, these reagents shall be those recommended by the manufacturer. Specifically, these reagents will be for:
6.4.1 Test Method A:
6.4.1.1 Sodium Hydroxide Coated Silica,
6.4.1.2 Quartz Wool,
6.4.1.3 Magnesium Perchlorate,
6.4.1.4 Copper Turnings,
6.4.1.5 Coated Calcium Oxide (Furnace Reagent),
6.4.1.6 Nitrogen Catalyst, and
6.4.1.7 Magnesium Oxide, for liquids.
6.4.2 Test Method B:
6.4.2.1 EA 1000 Reagent,
6.4.2.2 Silver Tungstate on MgO,
6.4.2.3 Silver Vanadate,
6.4.2.4 Quartz Wool,
6.4.2.5 Silver Gauze,
6.4.2.6 Copper Oxide,
6.4.2.7 Tungstic Oxide,
6.4.2.8 Cobalt Oxide,
6.4.2.9 Copper Powder,
6.4.2.10 Sodium Hydroxide Coated Silica,
6.4.2.11 Alumina,
6.4.2.12 Magnesium Perchlorate, and
6.4.2.13 Platinum Gauze.
6.4.3 Test Method C:
6.4.3.1 Quartz Wool,
6.4.3.2 Chromic Oxide (oxidation catalyst),
6.4.3.3 Silver Coated Cobalt Oxide,
6.4.3.4 Reduced Copper (reduction catalyst),
6.4.3.5 Magnesium Perchlorate,
6.4.3.6 Molecular Sieve, 3A 1/16 in. (1.6 mm),
6.4.3.7 Sodium Hydroxide Coated Silica,
6.4.3.8 Chromosorb, (Absorber, for liquid samples; calcined silica), and
6.4.3.9 Copper Grains.
7. Sampling, Test Specimens, and Test Units
7.1 Laboratory Sample - Take a representative sample as specified in Practices D4057 or D4177.
7.2 Test Specimen - Take an aliquot from the laboratory sample for analysis as follows:
7.2.1 Preparation - Warm viscous samples until they are fluid, and shake for 5 s.
7.2.2 Transfer - Use any convenient, clean syringe or pipet to transfer test specimens to the capsules as described in Section 9.
