Foreword
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document is Part 11 of GB/T 5750 Standard examination methods for drinking water. The following parts of GB/T 5750 have been issued:
——Part 1: General principles;
——Part 2: Collection and preservation of water samples;
——Part 3: Water analysis quality control;
——Part 4: Organoleptic and physical indices;
——Part 5: Inorganic nonmetallic indices;
——Part 6: Metal and metalloid indices;
——Part 7: Aggregate organic indices;
——Part 8: Organic indices;
——Part 9: Pesticides indices;
——Part 10: Disinfection by-products indices;
——Part 11: Disinfectants indices;
——Part 12: Microbiological indices;
——Part 13: Radiological indices.
This document replaces GB/T 5750.11-2006 Standard examination methods for drinking water - Disinfectants parameter. In addition to structural adjustment and editorial changes, the following main technical changes have been made with respect to GB/T 5750.11-2006:
a) The clause "Terms and definitions" has been added (see Clause 3 hereof);
b) Two examination methods have been added (see 4.3 and 5.1 hereof);
c) One examination method has been changed (see 4.1 hereof; 1.1 of Edition 2006);
d) The name of one indice has been changed from "free chlorine residual" to "free chlorine" (see Clause 4 hereof; Clause 1 of Edition 2006).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This document was proposed by and is under the jurisdiction of the National Health Commission of the People's Republic of China.
The previous editions of this document are as follows:
——This document was firstly issued as GB/T 5750-1985 in 1985 and firstly revised as GB/T 5750.11-2006 in 2006;
——This is the second revision.
Introduction
The series of standards GB/T 5750 Standard examination methods for drinking water, as the recommended national standards for drinking water examination technology, are compatible with GB 5749 Standards for drinking water quality, and are also served as an important technical support of GB 5749. They provide examination methods for implementing GB 5749 and carrying out hygienic safety evaluation of drinking water.
GB/T 5750 consists of 13 parts.
——Part 1: General principles. It provides the basic principles and requirements for water quality examination.
——Part 2: Collection and preservation of water samples. It provides the basic principles, measures and requirements of water sample collection, preservation, management, transportation and sampling quality control.
——Part 3: Water analysis quality control. It provides quality control requirements and methods for water quality examination and testing laboratories.
——Part 4: Organoleptic and physical indices. It provides corresponding examination methods for organoleptic and physical indices.
——Part 5: Inorganic nonmetallic indices. It provides corresponding examination methods for inorganic nonmetallic indices.
——Part 6: Metal and metalloid indices. It provides corresponding examination methods for metal and metalloid indices.
——Part 7: Aggregate organic indices. It provides corresponding examination methods for aggregate organic indices.
——Part 8: Organic indices. It provides corresponding examination methods for organic indices.
——Part 9: Pesticides indices. It provides corresponding examination methods for pesticides indices.
——Part 10: Disinfection by-products indices. It provides corresponding examination methods for disinfection by-products indices.
——Part 11: Disinfectants indices. It provides corresponding examination methods for disinfectants indices.
——Part 12: Microbiological indices. It provides corresponding examination methods for microbiological indices.
——Part 13: Radiological indices. It provides corresponding examination methods for radiological indices.
Standard examination methods for drinking water - Part 11: Disinfectants indices
1 Scope
This document specifies the methods for determining free chlorine, total chlorine, chloramine, chlorine dioxide, and ozone in drinking water, the methods for determining free chlorine (using N,N-diethyl-p-phenylenediamine (DPD) spectrophotometry and 3,3',5,5'-tetramethylbenzidine colorimetry) and chloramine in water sources, as well as the methods for determining available chlorine in chlorine-containing disinfectants.
This document is applicable to the determination of disinfectants indices in drinking water and/or water sources.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 5750.1 Standard examination methods for drinking water - Part 1: General principles
GB/T 5750.3 Standard examination methods for drinking water - Part 3: Water analysis quality control
GB/T 5750.4-2023 Standard examination methods for drinking water - Part 4: Organoleptic and physical indices
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 5750.1 and GB/T 5750.3 apply.
4 Free chlorine
4.1 N,N-diethyl-p-phenylenediamine (DPD) spectrophotometry
4.1.1 Minimum detectable mass concentration
The minimum detectable mass of this method is 0.1μg. If 10mL of water sample is taken, the minimum detectable mass concentration is 0.01mg/L.
This method is applicable to the determination of free chlorine and various forms of chlorine compounds in drinking water and water sources treated with chlorine-containing disinfectants.
High concentration of monochloramine can interfere with the determination of free chlorine. This interference can be eliminated by using arsenite or thioacetamide to regulate the reaction. Interference from oxidized manganese can be subtracted by running a blank water sample, while interference from chromate can be eliminated using thioacetamide.
4.1.2 Principle
DPD may react rapidly with free chlorine in water, producing a red color. Under the catalysis of iodide, monochloramine can also react with DPD to develop color. By adding iodide before DPD reagent, a portion of trichloramine may develop color together with free chlorine and monochloramine. By changing the order of reagent addition, the concentration of trichloramine can be determined.
Foreword i
Introduction iii
1 Scope
2 Normative references
3 Terms and definitions
4 Free chlorine
5 Total chlorine
6 Available chlorine in chlorine-containing disinfectant
7 Chloramine
8 Chlorine dioxide
9 Ozone
