3856/5 International Standard (ISO) ANs Inrmt Do Se Paints and varnishes - Determination of "soluble" metal content Part 5: Determination of hexavalent chromium content of the pigment portion of the liquid paint or the paint in powder form - Diphenylcarbazide spectrophotometric method Peintures et vernis -- Détermination de la teneur en metaux 《 solubles>) -- Partie 5: Détermination du chrome hexavalent contenu dans le pigment de la peinture liquide ou de la peinture en poudre - Methode spectrophotométrique a la diphenylcarbazide Second edition --- 1984-11-01 UDC 667.6 : 543.42 : 546.766 Ref. No. ISO 3856/5-1984 (E) 1-G/GO Descriptors : paints, varnishes, printing inks, pigments, chemical analysis, determinationofcontent,chromium, spectrophotometry, diphenylcarbazide. ISU Price based on 3 pages romIHS Not for Resal Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (Iso member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the 1so Council. They are approved in accordance with IsO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 3856/5 was prepared by Technical Committee ISO/TC 35, Paints and varnishes. IS0 3856/5 was first published in 1980. This second edition cancels and replaces the first edition, of which it constitutes a thorough revision. @ International Organization for Standardization, 1984 Printed in Switzerland Copyright InternationalOrganizationfor Standardization nsefromIHS Not for Resale ISO 3856/5-1984 (E) INTERNATIONAL STANDARD Paints and varnishes -- Determination of ""soluble'" metal content Part 5: Determination of hexavalent chromium content of the pigment portion of the liquid paint or the paint in powder form --- Diphenylcarbazide spectrophotometric method O Introduction 3 Principle This International Standard is a part of ISO 3856, Paints and Formation of a coloured complex from hexavalent chromium and diphenylcarbazide solution. After addition of ortho- varnishes -- Determination of"soluble"metal content. phosphoric acid and sulfuric acid, spectrophotometric measurement of the colour at a wavelength in the region of Scope and field of application 540 nm. This part of ISO 3856 describes a diphenylcarbazide spec- trophotometric method for the determination of the "soluble" Reagents hexavalent chromium content of the hydrochloric acid extract of the pigment portion of the liquid paint or of the paint ir During the analysis, use only reagents of recognized analytical powder form, prepared in accordance with sub-clause 8.2.3 of grade and only water of at least grade 3 purity according to IS0 6713 or other suitable International Standards. ISO 3696. The method is applicable to paints having hexavalent chromium contents in the range of about 0,05 to 5 % (m/ m). 4.1 Diphenylcarbazide, solution. Other methods can be used by agreement between the Dissolve 0,25 g diphenylcarbazide in a mixture of 50 ml of interested parties, provided that the methods are specific fo acetone and 50 ml of water. hexavalent chromium but this spectrophotometric method is the referee method in cases of dispute. 4.2 Sodium hydroxide, c(NaOH) = 2 mol/I solution. References 4.3 Sulfuric acid, c(H2SO4) = 1 mol/l. IsO 385/1, Laboratory glassware Burettes Part 1: General requirements. i) 4.4 Orthophosphoric acid, approximately 85 % (m/m) (o approximately 1,69 g/ml). Iso 1042, Laboratory glassware One-mark volumetric flasks. 4.5 Hydrochl