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GB/T 5750.1-2023 English PDF (GBT5750.1-2023)

GB/T 5750.1-2023 English PDF (GBT5750.1-2023)

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GB/T 5750.1-2023: Standard examination methods for drinking water - Part 1: General principles
This document stipulates the basic principles and requirements for drinking water quality inspection. This document applies to drinking water quality inspection, as well as water quality inspection of source water and drinking water that has been treated, stored, and transported.
GB/T 5750.1-2023
GB
NATIONAL STANDARD OF THE
PEOPLE'S REPUBLIC OF CHINA
ICS 13.060
CCS C 51
Replacing GB/T 5750.1-2006
Standard examination methods for drinking water - Part 1:
General principles
ISSUED ON: MARCH 17, 2023
IMPLEMENTED ON: OCTOBER 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 7
4 Selection of inspection methods ... 8
5 Report of test results ... 8
6 Reagents and concentration indication ... 9
7 Experimental water ... 10
8 Glassware and washing ... 11
9 Operation requirements for testing instruments and equipment ... 13
10 Laboratory safety ... 13
Standard examination methods for drinking water - Part 1:
General principles
1 Scope
This document stipulates the basic principles and requirements for drinking water quality inspection.
This document applies to drinking water quality inspection, as well as water quality inspection of source water and drinking water that has been treated, stored, and transported.
2 Normative references
The following documents contain the provisions which, through normative reference in this document, constitute the essential provisions of this document. For the dated referenced documents, only the versions with the indicated dates are applicable to this document; for the undated referenced documents, only the latest version (including all the amendments) is applicable to this document.
GB 4789.28 National food safety standard - Food microbiology testing - Quality Requirements for Media and Reagents
GB/T 6682 Water for analytical laboratory use - Specification and test methods GB 15603 General rules for the hazardous chemicals warehouse storage
GB 19489 Laboratories - General requirements for biosafety
JJG 196 Working Glass Container
3 Terms and definitions
The following terms and definitions apply to this document.
3.1 constant mass
Except for total dissolved solids, the mass difference after two consecutive dryings is less than 0.2 mg.
3.2 measure
The operation of using a measuring cylinder to take water samples or test solutions. 3.3 pipetting
The operation of taking water samples or testing liquid with plain pipets, graduated pipettes (also called pipets), or pipettes.
3.4 constant volume
The operation of diluting to the mark with pure water or other solvents in a volumetric flask.
3.5 minimum detectable mass
The lowest mass of the test object that can be accurately measured.
NOTE: The units are milligrams (mg), micrograms (μg), etc.
3.6 minimum detectable mass concentration
The mass concentration of the analyte corresponding to the minimum detectable mass. NOTE: The units are milligrams per liter (mg/L), micrograms per liter (μg/L), etc. 3.7 total minimum detectable mass concentration
The sum of 1/2 of the minimum detection mass concentration of all indicators for which the total quantity is limited.
4 Selection of inspection methods
If there are two or more inspection methods for the same project, the corresponding inspection method can be selected and used according to the equipment and technical conditions.
5 Report of test results
5.1 Test results that are lower than the minimum detectable mass concentration of the method shall be reported as "less than the minimum detectable mass concentration". 5.2 When reporting test results involving indicators required for total quantity limit, if the test result of each indicator is less than its minimum detectable mass concentration, report the result as "less than the total minimum detectable mass concentration"; if any indicator is detected, report as "the sum of the test results of the detected indicators and 1/2 of the minimum detectable mass concentration of the undetected indicators". third-grade water is used for general chemical analysis.
7.4 All grades of pure water shall be stored in sealed, dedicated containers. New containers shall be treated before use. They are usually soaked in 20% hydrochloric acid solution for 2 to 3 days, then rinsed repeatedly with pure water, filled with pure water and soaked for more than 6 hours, and then drained before use.
7.5 Since pure water may be contaminated by CO2, NH3, microorganisms, and other substances in the laboratory air as well as pollutants from the container wall during storage, the first-grade water cannot be stored and shall be prepared before use; the second-grade water and third-grade water can be prepared in appropriate amounts and stored in corresponding containers that have been pre-cleaned with water of the same grade.
7.6 Water used at all grades shall not be contaminated during transportation. 8 Glassware and washing
8.1 General requirements for glassware
8.1.1 Inspection and calibration of glassware: Volumetric flasks, burettes, plain pipets, graduated pipettes, etc. shall be inspected and calibrated in accordance with JJG 196. 8.1.2 When preparing a standard color array, a complete set of colorimetric tubes shall be used. The inner diameter and graduation of each tube shall be consistent, and the volume shall be corrected if necessary.
8.1.3 Glassware shall be thoroughly washed before use. For washing, the glassware can first be soaked and rinsed with tap water, then soaked and washed with washing liquid, then rinsed with tap water, and finally rinsed with pure water three times. The inner wall of the washed vessel shall be evenly wetted by water. If there are small water droplets or areas that do not touch water, it means there is grease on the wall of the vessel and it shall be washed again.
8.1.4 When washing glassware, new contamination shall be prevented. For example, glassware used for measuring iron cannot be washed with a wire handle brush, but can be washed with a plastic rod tied with foam plastic; glassware used for measuring zinc and iron cannot be rinsed with tap water after pickling and shall be rinsed directly with pure water; the vessels used for measuring ammonia and iodide shall be soaked in pure water after being washed.
8.1.5 If there are special requirements for the washing of vessels in the inspection method, the provisions in the inspection method shall prevail.
8.2 Preparation and use of washing liquid
8.2.1 A potassium dichromate cleaning solution is prepared and used as follows. a) Preparation of potassium dichromate washing solution: Prepare it with potassium dichromate solution and concentrated sulfuric acid. Weigh 100 g of finely ground potassium dichromate into a beaker, add about 100 mL of pure water, and slowly add concentrated sulfuric acid along the wall of the beaker while stirring with a glass rod (note: this process is an exothermic reaction, so sulfuric acid needs to be prevented from splashing out). When adding sulfuric acid, a red precipitate will precipitate; continue adding sulfuric acid until the precipitate is just dissolved.
b) Potassium dichromate washing liquid shall be stored in a glass bottle with a ground stopper to avoid absorbing water, and can be poured back into the bottle after use. After repeated use, the potassium dichromate in the washing liquid is reduced, and the color of the washing liquid changes to green-brown; the washing liquid is no longer oxidizing, and cannot be used again.
c) Potassium dichromate washing liquid is a strong oxidant, but its action is relatively slow. Therefore, the washed vessels shall be in full contact with the washing liquid and soaked for several minutes to several hours. After the vessels are washed with potassium dichromate washing liquid, they need to be fully washed with tap water (usually 7 to 10 times), and finally rinsed with pure water 3 times. For vessels washed with the washing liquid, special attention shall be paid to the interference of chromium and other impurities adsorbed on the walls of the vessel, especially the frosted parts, which may interfere with the test.
8.2.2 Alkaline potassium permanganate washing solution: Weigh 4 g of potassium permanganate, dissolve it in a small amount of water, add 10 g of potassium hydroxide, and dilute to 100 mL with water. It can be used to clean oil stains or other organic substances. After washing, brown manganese dioxide precipitates in the stained area of the container, which can be removed with hydrochloric acid (1+1) solution or oxalic acid lotion, ferrous sulfate, sodium sulfite, and other reducing agents. 8.2.3 Acidic oxalic acid or acidic hydroxylamine washing solution: Weigh 10 g of oxalic acid or 1 g of hydroxylamine hydrochloride and dissolve it in 100 mL of hydrochloric acid solution (1+4). It can be used to wash oxidizing substances.
8.2.4 Potassium hydroxide alcohol solution: Weigh 100 g of potassium hydroxide, add 50 mL of water to dissolve, and add alcohol to 1000 mL. It can be used to clean grease, resin, etc.
8.2.5 Nitric acid solution: When measuring metal ions, nitric acid solutions of different concentrations [commonly used (1+9)] can be used to soak and wash glassware.
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