7875/2 (TSO nternational Standard Water quality - Determination of surfactants Part 2: Determination of non-ionic surfactants using Dragendorff reagent Qualite de I'eau - Dosage des agents de surface -- Partie 2: Dosage des agents de surface non ioniques a I'aide du reactif de Dragendorff First edition - 1984-12-15 Ref. No. ISO 7875/2-1984 (E) UDC 543.3 : 661.185.1 Descriptors : water, quality, tests, determination, non-ionic surfactants. Price based on 6 pages Copyright International Organization for Standardization Not for Resale 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 ISo Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7875/2 was prepared byTechnical Committee iSo/Tc 147, Water quality. International Organization for Standardization, 1984 Printed in Switzerland r networking permitted without license from IHS No reproductio Not for Resale INTERNATIONAL STANDARD ISO 7875/2-1984 (E) Water quality -- Determination of surfactants Part 2: Determination of non-ionic surfactants using Dragendorff reagent 4 Principle 0 Introduction Air stripping of surfactants from the sample and collection in ethyl acetate. Removal of ethyl acetate and precipitation of the Anionic and non-ionic surface active substances, generally non-ionic surfactants with Dragendorff reagent (KBil4 + BaCi2 called surfactants, are used in synthetic products for general + acetic acid). cleaning purposes. Isolation and dissolution of the precipitate, and potentiometric ISo 7875 consists of the following parts : determination of the concentration of bismuth equivalent to the concentration of non-ionic surfactant with sodium pyrrolidin- Part 1: Determination of anionic surfactants by the 1-yl dithiocarboxylate solution. methylene blue spectrometric method. Part 2: Determination of non-ionic surfactants using Alternative methods for the determination of the bismuth ion Dragendorff reagent. are, among others, atomic absorption and UV spectrometry (see the annex), Scope 1 This part of IS0 7875 specifies a method for the determination Reagents of non-ionic surfactants in aqueous media using Dragendorff reagent. During the analysis, unless otherwise stated, use only reagents of recognized analytical grade, and only distilled water or water 2 Field of application of equivalent purity. This part of iso 7875 applies to the determination of low con- 5.1 Sodium chloride (NaCl). centrations of bismuth active substances (BiAS), i.e. non-ionic surfactants of the alkylphenol-alkylene oxide and alcohol- alkylene oxide adduct types, as long as they can be stripped 5.2 Sodium hydrogencarbonate (NaHCO3). and precipitated with Dragendorff reagent (for example eth- oxylates with about 5 to 30 ethylene oxide groups per 5.3 Ethyl acetate (C,HgO2), freshty distilled. molecule). The method is suitable for influents and effluents of sewage treatment plants and waste water. When investigating CAUTION -- Ethyl acetate is flammable and toxic. surface waters it may be necessary to handle large sample volumes (up to 5 000 ml). 5.4 Methanol (CHOH), freshly distilled, stored in a glass The detection limit is 0,05 mg/I for a 1 litre sample and the op- bottle. timum range of application is 250 to 800 μg. 5.5 Glacial-acetic acid (CHgCOOH), Q - 1,05 g/ml References 3 Lower