ASTM D565 Standard Test Method for Carbonizable Substances in White Mineral Oil
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 can 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 equipped to maintain a temperature of 100 +/- 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 can 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 or water of equal purity conforming to Type III of Specification D1193.
6.3 Cobaltous Chloride Solution (0.25 M) - Prepare a solution of hydrochloric acid (HCl) (Warning - Causes burns. Vapor extremely irritating.) by mixing 30 mL of concentrated HCl with 1170 mL of water. Slowly add the acid to the water. Dissolve 65 +/- 1 g of cobaltous chloride hexahydrate (CoCl2•6H2O) in the HCl solution to make 1000 mL of solution. Using a pipet, transfer 5 mL of this solution to a 250 mL iodine flask. Prepare a solution of sodium hydroxide (NaOH) (Warning - Corrosive. Can cause severe burns or blindness. Evolution of heat produces a violent reaction or eruption upon too rapid a mixture with water.) by mixing 5 g of NaOH with 20 mL of water. Add 15 mL of this NaOH solution to the iodine flask. Add 5 mL of hydrogen peroxide (H2O2) (3 % v/v). Boil for 10 +/- 1 min, cool, and add 2 g of potassium iodide (KI). Prepare a solution of H2SO4 (Warning - Causes burns. Vapor extremely irritating. Strong oxidizer.) by mixing 6 mL of H2SO4 with 18 mL of water. Slowly add the acid to the water (see Note 1). Add 20 mL of this H2SO4 solution to the flask.) When the precipitate has dissolved, titrate the liberated iodine with 0.100 M sodium thiosulfate (Na2S2O3) solution, using starch solution as an indicator. Each millilitre of Na2S2O3 solution is equivalent to 0.0238 g of CoCl2•6H2O. Adjust the final volume of CoCl2 solution by the addition of HCl solution so that 1 mL contains 59.5 mg of CoCl2•6H2O.
NOTE 1 - This freshly prepared H2SO4 solution will be hot. Allow to cool before continuing.
6.4 Cupric Sulfate Solution (0.25 M) - Prepare a solution of HCl (Warning - see 6.3) by mixing 30 mL of concentrated HCl with 1170 mL of water. Slowly add the acid to the water. Dissolve 65 +/- 1 g of cupric sulfate pentahydrate (CuSO4•5H2O) in enough HCl solution to make 1000 mL of solution. Using a pipet, transfet 10 mL of the solution to a 250-mL iodine flask, add 40 mL of water. Prepare a 6M acetic acid (CH3COOH) (Warning - Corrosive. Combustible. Vapor irritating.) solution by mixing 353 mL of concentrated CH3COOH with 1000 mL of water. Slowly add the acid to the water. Add 4 mL of 6M CH3COOH, 3 g of Kl and 5 mL of HCl to the flask. Titrate the liberated iodine with 0.100 M Na2S2O3 solution, using starch solution as an indicator. Each millilitre of Na2S2O3 solution is equivalent to 0.0250 g of CuSO4•5H2O. Adjust the final volume of the CuSO4 solution by the addition of diluted HCl solution so that 1 mL contains 62.4 mg CuSO4•5H2O.
6.5 Ferric Chloride Solution (0.166 M) - Prepare a solution of HCl (Warning - see 6.3) by mixing 30 mL of concentrated HCl with 1170 mL of water. Dissolve 55 +/- 1 g of ferric chloride hexahydrate (FeCl3•6H2O) in enough HCl to make 1000 mL of solution. Using a pipet, transfer 10 mL of this solution into a 250-mL iodine flask, add 15 mL water, 3 g KI and 5 mL HCl, and allow the mixture to stand for 15 +/- 1 min. Dilute with 100 mL of water and titrate the liberated iodine with 0.100 M Na2S2O3 solution, using starch solution as an indicator. Each millilitre of Na2S2O3 solution is equivalent to 0.0270 g of FeCl3•6H2O. Adjust the final volume of FeCl3 solution by the addition of the HCl solution so that 1 mL contains 45.0 mg of FeCl3•6H2O.
6.6 The solutions prepared in 6.3-6.5 may be prepared in different quantities, provided the ratios of components are equivalent.
6.7 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 the FeCl3 solution and 0.5 parts of the CuSO4 solution. Measure 5 mL of this mixture into a test tube as specified in 5.1. This pale amber reference standard shall then be overlaid with 5 mL of white mineral oil.
6.8 Sulfuric Acid (94.7 +/- 0.2 %) - The H2SO4 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 % nitric acid (HNO3).
