GB/T 629-2026Chemical reagent - Sodium hydroxide (English PDF)

6.2 Sodium hydroxide

6.2.1 Preparation of test solution Quickly weigh 25g of sample, place it in an Erlenmeyer flask, add.200mL of carbon dioxide-free water, and immediately stopper with a rubber stopper fitted with a soda lime tube. After dissolving, cool and transfer to a 250 mL volumetric flask, then dilute to the mark.

6.2.2 Determination Method Measure

10.00 mL of the test solution and pour it into a stoppered conical flask. Add 95 mL of carbon dioxide-free water and 5 mL of barium chloride solution. (100 g/L), shake well, and let stand for 15 minutes. Add 2 drops of phenolphthalein indicator solution (10 g/L), and titrate with standard hydrochloric acid solution [c(HCl) = 1 mol/L]. Titrate until the red color of the solution disappears. Retain the solution and continue to determine the sodium carbonate content. The mass fraction (w1) of sodium hydroxide is calculated according to formula (1).

6.3 Carbonates Add 10 drops of bromocresol green-methyl red indicator to the solution after sodium hydroxide determination (6.2.2), and titrate with standard hydrochloric acid solution. [c(HCl)=1mol/L] Titrate until the solution changes from green to dark red, boil for 2 minutes, cool, and continue titrating until the solution turns dark red. The mass fraction of sodium carbonate (w2) is calculated according to formula (2).

6.4 Clarity Test Take 100 mL of the test solution (6.2.1), and its turbidity should not exceed that of grade 2 (superior purity) and grade 4 as specified in Table 2 of HG/T 3484-1999. Clarity standard No. 6 (analytical grade) or No. 6 (chemically pure).

6.5 Chloride

6.5.1 Turbidimetric method (arbitration method) Take 5 mL of the test solution (6.2.1), neutralize it with nitric acid solution (25%), dilute it to 20 mL, and then test it according to the provisions of GB/T 9729. The turbidity of the solution should not exceed that of the standard turbidity solution. The standard turbidity solution is prepared by taking

0.010 mg (analytical grade),

0.025 mg (analytical grade), or

0.050 mg (chemically pure) chloride solution. (Cl) standard solution, diluted to 20 mL, and treated simultaneously with the same volume of test solution.

6.5.2 Ion Chromatography

6.5.2.1 Reagents, Materials and Instruments Comply with the provisions of Chapters 5 and 6 of GB/T 34672-2017.

6.5.2.2 Instrument Conditions Chromatographic column. 250 mm long, 4 mm inner diameter; polystyrene-divinylbenzene polymer with quaternary ammonium salt functional groups, particle size... 9µm, pH tolerance range 0~14, or other chromatographic columns that can achieve similar separation results. Rinsing solution. 15 mmol/L potassium hydroxide solution.

6.5.2.3 Determination Method Weigh

0.5 g to

1.0 g (accurate to 0.0001

g) of the sample into a 100 mL volumetric flask, dilute to the mark, shake well, and purify by hydrogen column chromatography. Then, the supernatant was filtered through a 0.22 µm filter membrane and used as the test solution. The determination was performed according to the provisions of

10.5.1 in GB/T 34672-2017, and a blank test was also performed. test.

6.5.2.4 Calculation The mass fraction of chloride (w3) is calculated according to formula (3).

6.6 Sulfates Take 10 mL (3 mL for chemically pure solutions, diluted to 10 mL) of the test solution (6.2.1), neutralize with 20% hydrochloric acid solution, and dilute to [the appropriate concentration]. 20 mL of solution was acidified with

0.5 mL of hydrochloric acid solution (20%) and then tested according to GB/T 9728.The turbidity of the solution should not exceed that of the standard ratio. Turbid solution. The standard turbidity solution is prepared by taking

0.02 mg (analytical grade),

0.05 mg (analytical grade), or

0.06 mg (chemically pure) of sulfate. (SO4) standard solution, diluted to 20 mL, was treated simultaneously with the same volume of test solution.

6.7 Total Nitrogen Content Take 20 mL of the test solution (6.2.1), dilute to 140 mL, and determine according to the provisions of

4.4.1 in GB/T 609-2018. The yellow color should not be deeper than that of the standard colorimetric solution. The standard colorimetric solution is prepared by taking a nitrogen (N) standard containing

0.01 mg (analytical grade),

0.02 mg (analytical grade), or

6.10.1 Flame Atomic Absorption Spectrometry (Arbitration Method)

6.10.1.1 Reagents, Materials and Instruments Comply with the provisions of Chapters 5 and 6 of GB/T 9723-2007.

6.10.1.2 Instrument Conditions Light source. magnesium hollow cathode lamp. Wavelength. 285.2nm. Flame. Acetylene-air.

6.10.1.3 Determination Method Weigh 10g of sample, dissolve in water, neutralize with 20% hydrochloric acid solution, and dilute to 100mL. Take 20mL of each solution, for a total of 4 portions. The determination shall be made in accordance with the provisions of

7.2.2 in GB/T 9723-2007, and the results shall be calculated in accordance with the provisions of

7.2.3 in GB/T 9723-2007.

6.10.2 Inductively Coupled Plasma Atomic Emission Spectrometry

6.10.2.1 Reagents, Materials and Instruments Comply with the provisions of Chapters 5 and 6 of GB/T 23942-2009.

6.10.2.2 Instrument Conditions Recommended wavelength. 279.553nm for magnesium. Incident power. 1300W. Observation height. 15mm. Argon flow rate.

0.55 L/min for carrier gas and

0.2 L/min for auxiliary gas. Solution extraction rate.

1.5 mL/min. Analysis time. rinsing 10s, exposure 5s. Plasma gas flow rate. 11 L/min. The above instrument conditions can be optimized according to specific circumstances.

6.10.2.3 Determination Method Weigh 10g of the sample and place it in a beaker. Add an appropriate amount of water and then 50mL of hydrochloric acid. After cooling to room temperature, transfer the solution to a 250mL volumetric flask. Dilute to the mark and mix well. Take 20 mL, making four portions, and place each portion into a 50 mL volumetric flask. Follow the procedure in GB/T 23942-2009, section 7.3.3. The determination shall be carried out in accordance with the provisions of GB/T 23942-2009, and the results shall be calculated in accordance with the provisions of 7.3.4.

6.11 Aluminum

6.11.1 Colorimetric method (arbitration method) Weigh 1g of sample, dissolve in water, neutralize with 20% hydrochloric acid solution, dilute to 10mL, and determine according to GB/T 9734. The red color of the solution should not be deeper than that of the standard colorimetric solution. The standard colorimetric solution is prepared by taking

0.01 mg (analytical grade),

0.02 mg (analytical grade), or

0.05 mg (chemically pure) aluminum (Al) standard solution. The standard solution was diluted to 10 mL and treated simultaneously with the same volume of the test solution.

6.11.2 Inductively Coupled Plasma Atomic Emission Spectrometry See 6.10.2.The recommended wavelength is 396.152 nm for aluminum.

6.12 Potassium

6.12.1 Reagents, Materials and Instruments Comply with the provisions of Chapters 5 and 6 of GB/T 9723-2007.

6.12.2 Instrument Conditions Light source. Potassium hollow cathode lamp. Wavelength. 766.5nm. Flame. Acetylene-air.

6.12.3 Determination Method Weigh 1g of sample, dissolve in water, neutralize with 20% hydrochloric acid solution, and dilute to 100 mL. Take 10 mL of each solution, for a total of 4 portions. The determination shall be made in accordance with the provisions of

7.2.2 in GB/T 9723-2007, and the results shall be calculated in accordance with the provisions of

7.2.3 in GB/T 9723-2007.

6.13 Calcium

6.13.1 Colorimetric method (arbitration method) Weigh 1g of sample, dissolve in water, neutralize with 20% hydrochloric acid solution, and dilute to 100mL. Take 10mL (2mL for chemically pure samples) and dilute. Add 10 mL of ethanol (95%),

0.5 mL of mixed alkali, and 1 mL of glyoxal bis(o-aminophenol) ethanol solution (2 g/L), and shake. Mix well, let stand for 5 minutes, extract with 5 mL of chloroform (temperature not exceeding 30°C), and immediately measure the color. The red color of the organic layer should not be deeper than the standard. Colorimetric solution. The standard colorimetric solution is prepared by taking a standard solution containing

0.002 mg (analytical grade) or

0.010 mg (analytical grade, chemically pure) of calcium (Ca) standard solution. The solution was diluted to 10 mL and treated simultaneously with the same volume of the test solution.

6.13.2 Flame Atomic Absorption Spectrometry See 6.10.1.The light source is a calcium hollow cathode lamp; the recommended wavelength is 422.7 nm.

6.13.3 Inductively Coupled Plasma Atomic Emission Spectrometry See 6.10.2.The recommended wavelength is 317.933 nm for calcium.

6.14 Iron

6.14.1 Colorimetric method (arbitration method) Take 10 mL of the test solution (6.2.1), adjust the pH of the solution to 2 with hydrochloric acid solution (20%), and then measure according to the provisions of GB/T 9739. The red color of the solution should not be deeper than that of the standard colorimetric solution. The standard colorimetric solution is prepared by taking

0.005 mg (analytical grade),

0.010 mg (analytical grade), or

0.020 mg (chemically pure) of iron (Fe) standard solution. The standard solution was diluted to 10 mL and treated simultaneously with the same volume of the test solution.

6.14.2 Inductively Coupled Plasma Atomic Emission Spectrometry See 6.10.2.The recommended wavelength is 238.204 nm for iron.

6.15 Nickel

6.15.1 Colorimetric method (arbitration method) Weigh 0.5g of the sample, dissolve it in water, neutralize it with hydrochloric acid solution (20%), dilute to 25mL, and add 2mL of dimethylglyoxime hydroxide. Mix sodium solution (10 g/L) and 1 mL potassium persulfate solution (50 g/L) and shake well. The red color of the solution should not be deeper than that of the standard colorimetric solution. The standard colorimetric solution is prepared by taking a standard solution containing

0.005 mg of nickel (Ni), diluting it to 25 mL, and simultaneously mixing it with an equal volume of test solution. deal with.

6.15.2 Inductively Coupled Plasma Atomic Emission Spectrometry See 6.10.2.The recommended wavelength is 231.604 nm for nickel.

6.16 Zinc

6.16.1 Flame Atomic Absorption Spectrometry (Arbitration Method) See 6.10.1.The light source is a zinc hollow cathode lamp; the recommended wavelength is 213.9 nm.

6.16.2 Inductively Coupled Plasma Atomic Emission Spectrometry See 6.10.2.The recommended wavelength is 206-200 nm for zinc.

6.17 Arsenic Take 20 mL of the test solution (6.2.1), neutralize it with 20% hydrochloric acid solution, dilute it to 30 mL, and then proceed according to GB/T 610-2008. The determination shall be performed in accordance with the provisions of 4.2.The purple-red color of the absorbent solution should not be deeper than that of the standard colorimetric solution. The standard colorimetric solution is prepared by taking a standard solution containing

0.002 mg of arsenic (As), diluting it to 30 mL, and then mixing it simultaneously with an equal volume of the test solution. Sample processing.

6.18 Heavy metals Take 10 mL of the test solution (6.2.1), add 2 mL of nitric acid, evaporate to dryness in a water bath, dissolve the residue in water, and then dissolve in sodium hydroxide solution (5 g/L). Adjust the pH of the solution to 4, dilute to 20 mL, and then determine according to the provisions of

5.1 in GB/T 9735-2008.The solution should not appear dark. It is darker than the standard colorimetric solution. The standard colorimetric solution is prepared by diluting a lead (Pb) standard solution containing

0.01 mg (analytical grade) and

0.03 mg (analytical grade, chemically pure) to a concentration of 100 mg/mL. 20 mL, and treated simultaneously and in the same manner as the same volume of test solution.