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
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 stron...