GB 8538-2022 National food safety standard - Methods for examination of natural mineral drinking water English
This standard replaces GB 8538-2016 National food safety standard Methods for examination of drinking natural mineral water. The following main changes have been made with respect to GB 8538-2016:
——Contents on the confirmation test for pseudomonas aeruginosa are added;
——Methods and requirements for sampling and preservation of water specimens for microbiological examination in Annex B are added;
——Manifold zymotechnics inspection method and applicable scope are modified for coliform bacteria;
——Confirmation test, counting method and counting medium are modified for clostridium perfringens.
National food safety standard Methods for examination of drinking natural mineral water
1 Scope
This standard specifies the methods for determination of drinking natural mineral water in terms of chromaticity, taste and smell, state, turbidity, pH, total dissolved solids, total hardness, total alkalinity, total acidity, multi-element determination, potassium and sodium, calcium, magnesium, iron, manganese, copper, zinc, total chromium, lead, cadmium, total mercury, silver, strontium, lithium, barium, vanadium, antimony, cobalt, nickel, aluminum, selenium, arsenic, borate, metasilicic acid, fluoride, chloride, iodide, carbon dioxide, nitrate, nitrite, carbonate and bicarbonate, sulfate, oxygen consumption, cyanide, volatile phenolic compounds, anionic synthetic detergents, mineral oil, bromate, sulfide, phosphate, total β radioactivity, tritium, 226Ra radioactivity, coliform bacteria, streptococcus faecalis, pseudomonas aeruginosa and clostridium perfringens.
This standard is applicable to the determination for the indexes of drinking natural mineral water.
2 Chromaticity
2.1 Principle
Prepare a standard color serial with the same yellow hue as natural water using potassium chloroplatinate and cobalt chloride for visual colorimetric determination of water specimen. It is specified that the color of 1mg/L Pt [in the form of (PtCl6) 2-] is taken as one degree in chromaticity unit, which is called 1°. Even slight turbidity will interfere with the determination, so turbid water specimens shall be centrifuged until they are clear.
2.2 Reagents and materials
Unless otherwise specified, reagents used in this method are all analytically pure, and water is the Grade 3 water as specified in GB/T 6682.
2.2.1 Potassium chloroplatinate (K2PtCl6).
2.2.2 Cobaltous chloride (CoCl2·6H2O).
2.2.3 Platinum-cobalt standard solution: accurately weigh 1.246g of potassium chloroplatinate (K2PtCl6) and 1.000g of dry cobalt chloride (CoCl2·6H2O), dissolve them in 100mL of water, then add 100mL of hydrochloric acid (ρ20 = 1.19g/mL), and dilute the solution to a constant volume of 1,000mL with water. The chromaticity of this standard solution is 500°.
2.3 Apparatuses
2.3.1 Colorless colorimetric tube without stopper: 50mL.
2.3.2 Centrifuge.
2.3.3 Analytical balance: with a sensibility of 0.1mg.
2.4 Analysis procedure
2.4.1 Treatment of specimens
Pipet 50mL of transparent water specimen into a colorimetric tube. If the chromaticity of water specimen is too high, a small amount of water specimen may be taken and diluted with water and then the color is compared; the result is multiplied by the dilution factor.
2.4.2 Determination
Take another colorimetric tubes and add platinum-cobalt standard solution (2.2.3) of 0mL, 0.50mL, 1.00mL, 1.50mL, 2.00mL, 2.50mL, 3.00mL, 3.50mL, 4.00mL, 4.50mL and 5.00mL respectively, dilute the solution to the scale with water and shake well, i.e. standard chromaticity series of 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45° and 50°.
Comparing the water specimen with the platinum-cobalt standard color series, if the hue of the water specimen is inconsistent with that of the standard series, it is regarded that the water specimen is of different color, which may be described in words.
2.5 Expression of analysis results
The specimen chromaticity shall be calculated using Equation (1):
(1)
where,
Chromaticity——the unit is °;
V1——the taken volume of platinum-cobalt standard solution, mL;
V——the volume of water specimen, mL.
3 Taste and smell
3.1 Analysis procedure of the taste
Take a small amount of water specimen into the mouth (the water specimen shall be harmless to human body), don't swallow it but taste, and describe and record the results with appropriate words.
3.2 Analysis procedure of the smell
Take 100mL of water specimen, put the solution in a 250mL conical bottle, shake it and smell the water from the bottle mouth, and describe and record the results with appropriate words.
4 State
Shake the water specimen well, observe the solution directly with naked eyes and record the results.
Foreword i
1 Scope
2 Chromaticity
3 Taste and smell
4 State
5 Turbidity
6 pH
7 Total dissolved solids
8 Total hardness
9 Total alkalinity
10 Total acidity
11 Multi-element determination
12 Potassium and sodium
13 Calcium
14 Magnesium
15 Iron
16 Manganese
17 Copper
18 Zinc
19 Total chromium
20 Lead
21 Cadmium
22 Total mercury
23 Silver
24 Strontium
25 Lithium
26 Barium
27 Vanadium
28 Antimony
29 Cobalt
30 Nickel
31 Aluminum
32 Selenium
33 Arsenic
34 Borate
35 Metasilicic acid
36 Fluoride
37 Chloride
38 Iodide
39 Carbon dioxide
40 Nitrate
41 Nitrite
42 Carbonate and bicarbonate
43 Sulfate
44 Oxygen consumption
45 Cyanide
46 Volatile phenolic compounds
47 Anionic synthetic detergents
48 Mineral oil
49 Bromate
50 Sulfide
51 Phosphate
52 Total β radioactivity
53 Tritium
54 226Ra radioactivity
55 Coliform bacteria
56 Streptococcus faecalis
57 Pseudomonas aeruginosa
58 Clostridium perfringens
Annex A Culture medium and reagents
Annex B Collection and storage of drinking natural mineral water
