ASTM D612 Standard Test Method for Carbonizable Substances in Paraffin Wax
5. Apparatus
5.1 Test Tube, as shown in Fig. 1, of heat-resistant glass fitted with a well-ground glass stopper, the stopper and the tube bearing identical and indestructible numbers. The tube shall be 140 +/- 2 mm in length and between 14.5 and 15.0 mm in outside diameter, and shall be calibrated at the 5 +/- 0.2-mL and 10 +/- 0.2-mL liquid levels. The capacity of the tube with stopper inserted shall be between 13.6 and 15.6 mL. A rolled edge may be provided for suspending the tube on the cover of the water bath.
5.2 Water Bath, suitable for immersing the test tube above the 10-mL line and equipped to maintain a temperature of 158 +/- 1.0°F (70 +/- 0.5°C). The bath shall be provided with a cover of any suitable material, with holes approximately 16 mm in diameter through which the test tubes may be suspended.
5.3 Color Comparator, of a suitable type for observing the color of the acid layer in comparison with the reference standard color solution. The size and shape of the comparator are optional, but the size and shape of the apertures shall conform to the dimensions prescribed in Fig. 1.
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 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean distilled water, such as reagent water corresponding to Specification D1193, Type III, or water of equal purity.
6.3 Cobaltous Chloride Solution (0.5 N) - Dissolve about 65 g of cobaltous chloride (CoCl2·6H2O) in enough diluted hydrochloric acid (HCl, 1 + 39) (Warning - Hydrochloric acid (concentrated) causes burns, vapor extremely irritating. See A1.2) to make 1000 mL of solution. Transfer exactly 5 mL of this solution to a flask; add 15 mL of sodium hydroxide (NaOH, 1 + 5) (Warning - Sodium hydroxide, corrosive, can cause severe burns or blindness. Evolution of heat produces a violent reaction or eruption upon too rapid a mixture with water. See A1.4), and 5 mL of hydrogen peroxide. Boil for 10 min, cool, and add 2 g of potassium iodide (KI) and 20 mL of sulfuric acid (H2SO4, 1 + 4) (Warning - Sulfuric acid (concentrated) causes burns, vapor irritating, strong oxidizer. See A1.3). When the precipitate has dissolved, titrate the liberated iodine with 0.1 N sodium thiosulfate (Na2S2O3) solution using starch solution as an indicator. Each millilitre of 0.1 N Na2S2O3 solution consumed is equivalent to 0.023799 g of CoCl2·6H2O. Adjust the final volume of CoCl2 solution by the addition of diluted HCl (1 + 39) so that 1 mL contains 59.5 mg of CoCl2·6H2O.
6.4 Colorimetric Reference Standard Solution - Prepare a reference standard pale amber solution for color comparison by mixing together 1.5 parts of CoCl2 solution, 3.0 parts of FeCl3 solution, and 0.5 parts of CuSO4 solution. Measure 5 mL of this mixture into a test tube as specified in 3.1. This pale amber reference standard shall then be overlaid with 5 mL of white mineral oil.
6.5 Cupric Sulfate Solution (0.5 N) - Dissolve about 65 g of cupric sulfate (CuSO4·5H2O) in enough diluted HCl (1 + 39) (Warning - Hydrochloric acid (concentrated) causes burns, vapor extremely irritating. See A1.2) to make 1000 mL of solution. Transfer exactly 10 mL of this solution to a flask, add 50 mL of water, 4 mL of acetic acid (Warning - Acetic acid (glacial) is corrosive, combustible, vapor irritating. See A1.5), and 3 g ofKI. Allow the mixture to stand for 5 min, then titrate the liberated iodine with 0.1 N Na2S2O3 solution, using starch solution as an indicator. Each millilitre of 0.1 N Na2S2O3 solution is equivalent to 0.02497 g of CuSO4·5H2O. Adjust the final volume of CuSO4 solution by the addition of diluted HCl (1 + 39) so that 1 mL contains 62.4 mg of CuSO4·5H2O.
6.6 Ferric Chloride Solution (0.5N) - Dissolve about 55 g of ferric chloride (FeCl3·6H2O) in enough diluted HCl (Warning - Hydrochloric acid (concentrated) causes burns, vapor extremely irritating. See A1.2) (1 + 39) to make 1000 mL of solution. Transfer exactly 10 mL of the solution to a flask, add 5 mL of HCl (sp gr 1.19), 25 mL of water, and about 3 g of KI. Stopper and allow the mixture to stand for 5 min. Dilute the mixture with 50 mL of water, and titrate the liberated iodine with 0.1 N Na2S2O3 solution, using starch solution as an indicator. Each millilitre of 0.1 N Na2S2O3 solution is equivalent to 0.02703 g of FeCl3·6H2O. Adjust the final volume of the FeCl3 solution by the addition of diluted HCl (1 + 39) so that 1 mL contains 45.0 mg of FeCl3·6H2O.
6.7 Sulfuric Acid (94.7 +/- 0.2 %) - The sulfuric acid (H2SO4) (Warning - Sulfuric acid (concentrated) causes burns, vapor irritating, strong oxidizer. See A1.3) shall be nitrogen-free when analyzed in accordance with the following procedure: Dilute a small amount of the acid with an equal volume of water and superimpose 10 mL of the cooled liquid upon diphenylamine solution (1 g of diphenylamine in 100 mL of concentrated H2SO4). A blue color should not appear at the zone of contact within 1 h. This test detects as little as 0.0002 % NO3.
