ISO INTERNATIONAL STANDARD 3012 Third edition 1999-05-01 Petroleum products Determination of thiol (mercaptan) sulfur in light and middle distillate fuels Potentiometric method Produits pétroliers -Determination de la teneur en soufre sous forme de potentiometrie ISO Referencenumber ISO 3012:1999(E) by IHS under lic itted without license from IHS Not for Resale ISO 3012:1999(E) Foreword ISO(theInternationalOrganizationforStandardization)isaworldwidefederationofnationalstandardsbodies(lSO memberbodies).The work ofpreparingInternational Standards is normally carriedout throughISO technical liaison with ISO, also take part in the work. isO collaborates closely with the International Electrotechnical Commission(lEC)onallmattersofelectrotechnicalstandardization International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. International Standard ISO 3012 was prepared by Technical Committee ISO/TC 28, Petroleum products and lubricants. revision. @ISO1999 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic nternationalOrganizationforStandardization Casepostale56·CH-1211Geneve20·Switzerland Internet [email protected] Printed in Switzerland ional Organization for Standardizatior INTERNATIONAL STANDARD@ISO ISO 3012:1999(E) Petroleum products Determination of thiol (mercaptan) sulfur in light and middle distillate fuels Potentiometric method WARNING - The use of this International Standard may involve hazardous materials, operations and with its use. It is the responsibility of the user of this International Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope This International Standard specifies a method for the determination of thiol (mercaptan) sulfur in light distillates: suchasgasolinesandnaphthafractions,andmiddledistillatefuels,suchaskerosinesandgasoils,intherangeot 0,000 3 % (m/m) to 0,010 0 % (m/m) (3 mg/kg to 100 mg/kg). Organic sulfur compounds such as sulfides, disulfides and thiophene do not interfere. Elemental sulfur does not interfere at contents less than 0,ooo 5 % (m/m). Hydrogen sulfideinterferes,if notremovedasdescribedin8.2. NOTE For the purposes of this International Standard, the term "% (m/m)" is used to represent the mass fraction of a material. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigatethepossibilityof applyingthemost recenteditionsofthenormativedocumentsindicatedbelow.Fol undated references, the lates edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. IsO 3170:1988, Petroleum liquids -Manual sampling. IsO 3171:1988, Petroleum liquids -Automatic pipeline sampling. Iso 3675:1998, Crude petroleum and liquid petroleum products - Laboratory determination of density - Hydrometer method IsO 3696:1987, Water for analytical laboratory use - Specification and test methods. IsO 12185:1996, Crude petroleum and petroleum products -Determination of density-Oscillating U-tube method. 3 Principle A hydrogen sulfide-free sample is dissolved in an alcoholic sodium acetate titration solvent and the solution potential between a glass reference electrode and a silver/silver sulfide indicating electrode. Under these conditions point in the curve of titrated volume versus cell potential. Copyright Intern nal Organization for Standardizatior 1