Overview

Methods using flow analysis automate wet chemical procedures and are particularly suitable for the processing of many analytes in water in large numbers of samples at a high analysis frequency (up to 100 samples per hour). Analyses can be made using flow injection analysis (FIA) and continuous flow analysis (CFA). Both methods share the feature of an automatic dosage of the sample into a flow system (manifold) where the analytes in the sample react with the reagent solutions on their way through the manifold. The sample preparation may be integrated in the manifold. The reaction product is measured in a flow detector (for example, a photometer). The detector produces a signal from which the concentration of the parameter is calculated. The MBAS (methylene blue active substances) index is an analytical convention (a method-defined parameter) used for water quality control purposes. It measures surfactants and other substances that react with methylene blue under specified conditions. Depending on the objective of the analysis, a check shall be made on a case-by-case basis as to whether and to what extent additional conditions will have to be specified. The user should be aware that particular problems could require the specification of additional conditions. This International Standard specifies a procedure for the determination of the methylene blue active substances (MBAS) index, in the ranges 0,05 mg/l to 0,5 mg/l and 0,5 mg/l to 5,0 mg/l, in various water samples (for example, ground water, drinking water, surface water, waste water and leachates). Anionic surfactants are the most important substances showing methylene blue activity. This method is therefore useful for estimating the anionic surfactant content (including anionic surfactants with carboxylate groups (for example, soaps)) of water. Other types of substance may also show methylene blue activity and contribute to the result. On a case-by-case basis, the range of the analysis may be changed and the method used for other concentration ranges provided they cover exactly one decade of concentration units. This document has been prepared by Technical Committee ISO/TC 147 "Water quality" of the International Organization of Standardization (ISO) and has been adopted by Technical Committee CEN/TC 230 "Water analysis", the secretariat of which is held by DIN. The responsible German committee is NA 119-01-03-01-05 AK "Fließanalysenverfahren" ("Flow analytics method") of NA 119-01-03 AA "Wasseruntersuchung" ("Water analysis") at the Water Practice Standards Committee (NAW).

Document: references other documents

Responsible national committee

NA 119-01-03 AA - Water quality (CEN/TC 230, ISO/TC 147)  

Responsible european committee

CEN/TC 230 - Water analysis  

Responsible international committee

ISO/TC 147/SC 2 - Physical, chemical and biochemical methods