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GB/T 5750.11-2006 English PDF (GBT5750.11-2006)

GB/T 5750.11-2006 English PDF (GBT5750.11-2006)

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GB/T 5750.11-2006: Standard examination methods for drinking water -- Disinfectants parameters

This standard specifies the use of iodometric method for the determination of available chlorine in chlorine disinfectants. This method is applicable to the determination of available chlorine in solid or liquid chlorine-containing disinfectants.
GB/T 5750.11-2006
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 13.060
C 51
Partially replacing GB/T 5750-1985
Standard examination methods for drinking water -
Disinfectants parameters
ISSUED ON. DECEMBER 29, 2006
IMPLEMENTED ON. JULY 01, 2007
Issued by. Ministry of Health of PEOPLE Republic of China;
Standardization Administration of PRC.
Table of Contents
Foreword . 3
1 Free residual chlorine .. 5
2 Available chlorine in chlorine disinfectant . 11
3 Chloramine . 13
4 Chlorine dioxide .. 13
5 Ozone . 27
6 Chlorate . 34
Appendix A (Normative) References .. 35
Foreword
GB/T 5750 ?€?Standard examination methods for drinking water?€? is divided into the following parts.
- General principles;
- Collection and preservation of water samples;
- Water analysis quality control;
- Organoleptic and physical parameters;
- Nonmetal parameters;
- Aggregate organic parameters;
- Organic parameters;
- Pesticides parameters;
- Disinfection by-products parameters;
- Disinfectants parameter;
- Microbiological parameters;
- Radiological parameters.
This standard replaces the residual chlorine in Part II of GB/T 5750-1985 Standard examination methods for drinking water.
As compared with GB/T 5750-1985, the main changes are as follows.
- ADJUST the structure in accordance with GB/T 1.1-2000 Directives for
standardization-Part 1. Rules for the structure and drafting of standards and GB/T 20001.4-2001 Rules for drafting standards - Part 4. Methods of
chemical analysis;
- REVISE the quantity and unit of measurement in accordance with the
requirements of national standards;
- CHANGE the equivalent concentration into the molar concentration (the redox part still retains the equivalent concentration);
- CHANGE the mass concentration symbol C into ??, CHANGE the content
symbol from M into m;
Standard examination methods for drinking water -
Disinfectants parameters
1 Free residual chlorine
1.1 N,N-Diethyl-p-phenylenediamine (DPD) spectrophotometry
1.1.1 Scope
This standard specifies the use of N,N-diethyl-p-phenylenediamine (DPD) spectrophotometric method to determine free residual chlorine in drinking water and its source water.
This method is applicable to the determination of free residual chlorine and combined residual chlorine in various forms in drinking water and its source water after chlorination and disinfection.
The minimum detection mass of this method is 0.1 ??g. If a 10 mL water sample is taken for the determination, the minimum detection mass concentration is 0.01 mg/L.
High concentrations of monochloramine interfere with the determination of free residual chlorine, arsenite or thioacetamide can be used to control the reaction to remove interference. Manganese oxide interference can be eliminated from making the water sample blank. Chromate interference can be eliminated with thioacetamide.
1.1.2 Principle
DPD reacts rapidly with free chlorine in water to produce red color. Under the catalysis of iodide, monochloramine also reacts with DPD to develop color. When iodide is added prior to the addition of the DPD reagent, a portion of the trichloramine is developed with the free residual chlorine, and the concentration of trichloramine can be determined by changing the order of addition of the shift reagent. This method can use potassium permanganate solution to prepare a permanent standard series.
1.1.3 Reagents
1.1.3.1 Potassium iodide crystals.
1.1.3.2 Potassium iodide solution (5 g/L). WEIGH 0.50 g of potassium iodide (Kl), DISSOLVE it in fresh boiled cold purified water, DILUTE it to 100 mL. permanganate in the standard solution is similar to the DPD and the red color of the indicated residual chlorine.
1.1.3.9 Chlorine standard use solution [p(Cl2) = 1 ??g/mL]. PIPETTE 10.0 mL of chlorine standard stock solution (1.1.3.8), ADD pure water to dilute it to 100 mL. MIX it uniformly, TAKE 1.00 mL and DILUTE it to 100 mL.
1.1.4 Instruments
1.1.4.1 Spectrophotometer.
1.1.4.2 Stoppered colorimetric tube, 10 mL.
1.1.5 Analytical procedure
1.1.5.1 Standard curve drawing. PIPETTE 0, 0.1, 0.5, 2.0, 4.0, 8.0 mL of chlorine standard use solution (1.1.3.9) into six 10 mL stoppered colorimetric tubes, USE water requiring no chlorine (1.1.3.7) to dilute it to the mark. Respectively ADD 0.5 mL of phosphate buffer solution (1.3.3.3) and 0.5 mL of DPD solution (1.1.3.4), MIX it uniformly. DETERMINE the absorbance at a wavelength of 515 nm in a 1 cm cuvette with pure water as a reference. DRAW a standard curve.
1.1.5.2 PIPETTE 10 mL of water sample into a 10 mL colorimetric tube, ADD 0.5 mL phosphate buffer solution (1.1.3.3), 0.5 mL of DPD solution (1.1.3.4), MIX it uniformly; immediately DETERMINE the absorbance at a wavelength of 515 nm in a 1 cm cuvette with pure water as a reference, RECORD the reading as A, meanwhile MEASURE the sample blank value, DEDUCT it from the
reading.
Note. If the content of monochloramine in the sample is too high, the water sample can be treated with arsenite or thioacetamide.
1.1.5.3 CONTINUE adding a small crystal of iodinated crystal (about 0.1 mg) to the above test tube. After mixing it uniformly, MEASURE the absorbance, RECORD the reading as B.
Note. If the content of dichloramine in the sample is too high, it may add 0.1 mL of freshly prepared potassium iodide solution (1 g/L).
1.1.5.4 Then ADD potassium iodide crystal (about 0.1 g) to the above tube, MIX it uniformly. After 2 min, MEASURE the absorbance and RECORD the reading as C.
1.1.5.5 Take another two 10 mL colorimetric tubes, TAKE 10 mL of water sample in one of the colorimetric tubes, then ADD a small amount of potassium iodide crystal (about 0.1 mg), MIX it uniformly; ADD 0.5 mL of buffer solution (1.1.3.3) and 0.5 mL of DPD solution (1.1.3.4) into the second colorimetric tube, POUR 4.1.1 Scope
This standard specifies the use of N,N-diethyl-p-phenylenediamine (DPD)- ammonium ferrous sulfate titration method for the determination of chlorine dioxide in drinking water.
This method applies to the determination of chlorine dioxide in drinking water. The method requires that the total available chlorine (Cl2) of the water sample be no higher than 5 mg/L. Once above this value, the sample must be diluted. The determination scope of this method is 0.025 mg/L ~ 9.5 mg/L, the minimum detection concentration is 0.025 mg/L (ClO2).
Oxidized manganese and chromate can make DPD produce color, resulting in high measurement results, it may add sodium arsenite or thioacetamide to the water sample to correct it; since the entering of titration solution into iron ion can activate chlorite and interfere with the titration end, it can add
ethylenediaminetetraacetic acid disodium to inhibit it.
4.1.2 Principle
Glycine converts free chlorine in water to glycine chloride without disturbing the determination of chlorine dioxide. Chlorine dioxide in water reacts with DPD in red. It is titrated with ammonium ferrous sulfate standard solution. The addition of phosphate buffer salt will keep the water sample neutral. Under this condition, chlorine dioxide gets only 1 mol of electrons and is reduced to ClO2-. The amount of ammonium ferrous sulfate in the water sample can be used to
calculate the mass concentration of the oxygen dioxide.
4.1.3 Reagents
4.1.3.1 Potassium dichromate standard solution [c(1/6K2Cr2O7) = 0.1000 mol/L]. WEIGH 4.904 g of the dried reference potassium dichromate, DISSOLVE it in distilled water, MAKE its volume reach to 1000 mL, STORE it ground glass bottles.
4.1.3.2 Bismuth diphenylamine sulfonate solution (1 g/L). WEIGH 0.1 g of diphenylamine sulfonic acid hydrazine [(C6H5NHC6H4-SO3)2Ba] in 100 mL of distilled water.
4.1.3.3 Ammonium ferrous sulfate standard solution {c[(NH4)2Fe(SO4)2] = 0.003000 mol/L}. WEIGH 1.176 g of ammonium ferrous sulfate
[Fe(NH4)2(SO4)2?€?6H2O] into the distilled water containing 1 mL of sulfuric acid solution (1 + 3), USE the newly boiling and cooled distilled water to dilute it to 1000 mL. USE the potassium dichromate standard solution to calibrate the concentration in accordance with the following method, this solution can be c - Concentration of ammonium ferrous sulfate standard solution, in moles per liter (mol/L);
V2 - The volume of the ammonium ferrous sulfate solution consumed during the titration of the water sample, in milliliters (mL);
V1 - Volume of ammonium ferric [translator note. should be ferrous] sulfate standard solution consumed by the oxidized manganese and chromate in
water, in milliliters (mL);
V - Volume of water sample, in milliliters (mL);
13.49 ?? 5 - The actual mass of chlorine dioxide in milligrams equivalent to 1.00 mL of ammonium ferrous sulfate {c[(NH4)2Fe(SO4)2] = 1.000 mol/L.
4.2 Iodometric method
4.2.1 Scope
This standard specifies the use of iodometric method for the determination of chlorine dioxide in pure chlorine dioxide aqueous solution.
This method is applicable to the determination of chlorine dioxide in pure chlorine dioxide solution.
The minimum detection mass of this method is 10 ??g (by ClO2). If 500 mL of aqueous solution is used, the minimum detection mass concentration is 20 ??g/L (by ClO2). Temperature and strong-light can affect the stability of the solution, so the chlorine dioxide stock solution shall be protected from light, sealed, and stored refrigerated. In order to minimize the loss of chlorine dioxide, the preparation and calibration procedures are required to be performed at room temperature not exceeding 20 ??C and in non-direct light.
4.2.2 Principle
Sodium chlorite solution (NaClO2) reacts with dilute sulfuric acid to produce chlorine dioxide. Impurities such as chlorine are removed ...

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