ASTM D6920 Standard Test Method for Total Sulfur in Naphthas, Distillates, Reformulated Gasolines, Diesels, Biodiesels, and Motor Fuels by Oxidative Combustion and Electrochemical Detection
1. Scope
1.1 This test method covers the determination of total sulfur in liquid hydrocarbons, boiling in the range from approximately 25 to 400°C, with viscosities between approximately 0.2 and 10 cSt (mm/S) at room temperature. This test method is applicable to naphthas, distillates, and motor fuels such as gasolines, reformulated gasolines, gasohols, diesels and biodiesels containing approximately 1 to 100 mg/kg total sulfur in gasoline type products, and approximately 1 to 40 mg/kg sulfur in diesel type products.
1.2 The detector response for this technique within the scope of this test method is linear with sulfur concentration.
1.3 Based on interlaboratory study, the pooled limit of quantitation of this test method is 3 mg/kg for gasoline and <0.5 mg/kg for diesel samples.
1.4 This test method meets the U.S. EPA requirements for measuring sulfur in ultra low sulfur diesel fuels by the designated Test Method D 6428, as published in the U.S. Federal Register § 80.520(a)(1).
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Sections 8 and 9.
2. Referenced Documents
2.1 ASTM Standards:
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance Techniques to Evaluate Analytical Measurement System Performance
D6428 Test Method for Total Sulfur in Liquid Aromatic Hydrocarbons and Their Derivatives by Oxidative Combustion and Electrochemical Detection
D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories
2.2 U. S. Federal Register:
§ 80.520(a)(1) Vol. 68, No. 100(4)
3. Terminology
3.1 Definitions:
3.1.1 oxidative combustion, n - process in which a sample undergoes combustion in an oxygen rich environment at temperatures greater than 650°C and compounds decompose to carbon dioxide, water, and elemental oxides.
3.1.2 quartz combustion tube devitrification, n - process in which samples containing alkali-metals (that is, elements from the Periodic Table Group IA, for example, sodium, potassium, etc.) or alkaline earth (that is, elements from the Periodic Table Group IIA, for example, calcium, magnesium, etc.) will cause quartz to devitrify (that is, become milky white and brittle) at elevated temperatures.
3.1.2.1 Discussion - It is suggested that the quartz combustion tube temperature be kept <1200°C in order to minimize or eliminate the possibility of quartz combustion tube devitrification from occurring.
