SH/T 0079-1991 Preparation methods of reagent solutions for petroleum product testing

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Incomplete source card: Sections 10, 11, 12, 13, 14 are absent from the available source. Only available content is translated; source completion is pending.

Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: SH/T 0079-91
• Full name: Preparation methods of reagent solutions for petroleum product testing
• English name: not provided in the available source
• Replacement relationship: replaces SY 2002-76 (confirmed in 1988)
• Approval/implementation: approved by China Petrochemical Corporation 1991-11-26, implemented on 1992-12-01

2. Scope of application and non-applicability

• Scope of application: This standard specifies the preparation and standardization of standard volumetric solutions for petroleum product testing, as well as the preparation methods of reference solutions, other solutions, commonly used indicator liquids, and indicators.
• Not applicable: not provided in the available source.

3. Method principle

• Not provided in the available source (this standard is a reagent solution preparation method and does not have a separate method principle section).

4. Reagents and materials (purity / preparation)

• 3.1 The water used in this standard, unless otherwise specified, shall comply with the grade three water specifications in GB 6682. The ethanol used refers to 95% ethanol (analytical reagent).
• 3.2 Except for solutions for which the solvent has been specified, all solutions in this standard are aqueous solutions.
• 3.3 The reagents used in this standard for standardizing standard volumetric solutions and preparing reference solutions are volumetric analysis reference reagents. The purity of reagents used for preparing solutions shall not be lower than analytical reagent.
• 3.5 The mass of reagent weighed in this standard shall be within ±10% of the specified mass.
• 3.6 Standard volumetric solutions with a concentration equal to or lower than 0.02 mol/L in this standard shall be prepared immediately before use, and may be prepared by diluting a higher-concentration standard volumetric solution with boiled and cooled water, and restandardized if necessary.
• 3.8 The concentration values of standard volumetric solutions and reference solutions in this standard shall be taken to four significant figures.
• 3.9 The difference between the concentration value of the standard volumetric solution prepared in this standard and the specified concentration value shall not be greater than ±5% of the specified concentration value.
• 3.11 The validity period at room temperature (15~25℃) of standard volumetric solutions and reference solutions in this standard: potassium hydroxide-ethanol (or isopropanol) standard volumetric solution and hydrochloric acid-ethanol (or isopropanol) standard volumetric solution are 15 d, and other standard volumetric solutions and reference solutions are two months.

Preparation and standardization of each standard volumetric solution (Chapter 4):

• 4.1 Hydrochloric acid standard volumetric solution: c(HCl)=0.5, 0.1, 0.05 mol/L. Preparation: measure hydrochloric acid [36%~38%(m/m)] 45, 9.0, 4.5 mL and inject into 1L water, shake well. Standardization: reference anhydrous sodium carbonate is ignited at 270~300℃ to constant weight; for 0.5 mol/L take 0.8 g, for 0.1 mol/L take 0.17 g, for 0.05 mol/L take 0.08 g, accurate to 0.0002 g, dissolve in 50 mL water, add 10 drops of bromocresol green-methyl red mixed indicator liquid (clause 7.5), titrate until the color changes from green to dark red, boil for 2~3 min, after cooling continue titrating until dark red appears again, and perform a blank test at the same time. Comparison: measure 30.00~35.00 mL sodium hydroxide standard volumetric solution, add 50 mL carbon dioxide-free water and 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate, and when near the endpoint heat to 80℃, continue titrating until the color changes from pink to colorless.
• 4.2 Hydrochloric acid-ethanol (or isopropanol) standard volumetric solution: c(HCl)=0.2, 0.1, 0.05 mol/L. Preparation: measure hydrochloric acid [36%~38%(m/m)] 18, 9.0, 4.5 mL and inject into 1L ethanol (or isopropanol), shake well. Standardization: reference anhydrous sodium carbonate is ignited at 270~300℃ to constant weight; for 0.2 mol/L take 0.4 g, for 0.1 mol/L take 0.17 g, for 0.05 mol/L take 0.08 g, accurate to 0.0002 g, dissolve in 50 mL water, add 10 drops of bromocresol green-methyl red mixed indicator liquid (clause 7.5), titrate until the color changes from green to dark red, boil for 2~3 min, after cooling continue titrating until dark red appears again, and perform a blank test at the same time. Comparison: measure 30.00~35.00 mL sodium hydroxide standard volumetric solution, add 50 mL carbon dioxide-free water and 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate, and when near the endpoint heat to 80℃, continue titrating until the color changes from pink to colorless.
• 4.3 Sulfuric acid standard volumetric solution: c(½H₂SO₄)=0.1 mol/L. Preparation: measure 3 mL sulfuric acid [96%~98%(m/m)] and slowly inject into 1L water, cool, and shake well. Standardization: weigh 0.2 g reference anhydrous sodium carbonate ignited at 270~300℃ to constant weight, accurate to 0.0002 g, dissolve in 50 mL water, add 10 drops of bromocresol green-methyl red mixed indicator liquid (clause 7.5), titrate until the color changes from green to dark red, boil for 2~3 min, after cooling continue titrating until dark red appears again, and perform a blank test at the same time. Comparison: measure 30.00~35.00 mL sodium hydroxide standard volumetric solution [c(NaOH)=0.1 mol/L], add 50 mL carbon dioxide-free water and 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate, and when near the endpoint heat to 80℃, continue titrating until the color changes from pink to colorless.
• 4.4 Sodium hydroxide standard volumetric solution: c(NaOH)=0.5, 0.1, 0.05 mol/L. Preparation: prepare sodium hydroxide into a saturated solution with carbon dioxide-free water, place in a polyethylene container, seal and let stand until the solution is clear. Measure the supernatant liquid 26, 5.2, 2.6 mL and inject into 1L water. Standardization: reference potassium hydrogen phthalate is dried at 105~110℃ to constant weight; for 0.5 mol/L take 3.0 g, for 0.1 mol/L take 0.6 g, for 0.05 mol/L take 0.3 g, accurate to 0.0002 g, dissolve in 80 mL carbon dioxide-free water, add 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate until pink appears, and perform a blank test at the same time. Comparison: measure 30.00~35.00 mL hydrochloric acid standard volumetric solution, add 50 mL carbon dioxide-free water and 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate, and when near the endpoint heat to 80℃, continue titrating until pink appears.
• 4.5 Potassium hydroxide standard volumetric solution: c(KOH)=0.1, 0.05, 0.025 mol/L. Preparation: weigh potassium hydroxide 5.6, 2.8, 1.4 g, dissolve in 1L carbon dioxide-free water, and shake well. Standardization: reference potassium hydrogen phthalate is dried at 105~110℃ to constant weight; for 0.1 mol/L take 0.6 g, for 0.05 mol/L take 0.3 g, for 0.025 mol/L take 0.15 g, accurate to 0.0002 g, dissolve in 80, 80, 50 mL carbon dioxide-free water, add 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate until pink appears, and perform a blank test at the same time. Comparison: measure 30.00~35.00 mL hydrochloric acid standard volumetric solution, add 50 mL carbon dioxide-free water and 2~3 drops of phenolphthalein-ethanol indicator liquid (10 g/L), titrate, and when near the endpoint heat to 80℃, continue titrating until pink appears.
• 4.6 Potassium hydroxide-ethanol (or isopropanol) standard titration solution: c(KOH)=1.0, 0.5, 0.2, 0.1, 0.05 mol/L. Preparation (ethanol): The ethanol used must be refined (Note: weigh 1.5 g silver nitrate, 3 g potassium hydroxide, dissolve each in 10 mL water, pour into 1L 95% ethanol or anhydrous ethanol, shake for 3~4 min, after standing filter into a distillation flask and distill, collect the 78℃ fraction, store in a brown glass-stoppered bottle). Weigh potassium hydroxide 56, 28, 12, 6, 3 g, dissolve in 100 mL water, then dilute with 900 mL refined ethanol, shake well, store in a brown glass-stoppered bottle, after standing for 24 h take the supernatant liquid for standardization. Preparation (isopropanol): weigh potassium hydroxide according to the amount specified in 4.6.1.1, add to a flask containing 1L anhydrous isopropanol (water content less than 0.9%), install a reflux condenser, heat and shake continuously, slowly boil for 20 min, after potassium hydroxide is completely dissolved cool for a moment, then add at least 2 g barium hydroxide (generally 4~5 g), then slowly boil for at least 30 min, cool to room temperature, stand, after the upper solution becomes clear carefully pour the supernatant into a brown bottle, preferably attach an alkali asbestos drying tube at the bottle mouth. Standardization: reference potassium hydrogen phthalate dried at 105~110℃ to constant weight, 1.0 mol/L take 6.0 g, 0.5 mol/L take 3.0 g, 0.2 mol/L take 1.2 g, 0.1 mol/L take 0.6 g, 0.05 mol/L take 0.3 g, accurate to 0.0002 g, dissolve in 80 mL carbon dioxide-free water, add 2~3 drops of phenolphthalein-ethanol indicator solution (10 g/L), titrate until pink, and simultaneously perform a blank test.
• 4.7 Sodium thiosulfate standard titration solution: c(Na₂S₂O₃)=0.1, 0.05 mol/L. Preparation: weigh sodium thiosulfate 26, 13 g, dissolve in 1L water, slowly boil for 10 min, add chloroform 0.25~0.40, 0.20 mL, shake well, store in a brown bottle, after standing for two weeks filter or take the supernatant liquid for standardization. Standardization: reference potassium dichromate dried at 120℃ to constant weight, 0.1 mol/L take 0.15 g, 0.05 mol/L take 0.08 g, accurate to 0.0002 g, place in a glass-stoppered conical flask, dissolve with 25 mL water, add 2 g potassium iodide and 20 mL sulfuric acid solution [18%(m/m)], shake well, place in the dark for 10 min then add 150 mL water, titrate until light yellow then add 3 mL starch indicator solution (5 g/L), continue titrating until the color changes from blue to bright green, and simultaneously perform a blank test.
• 4.8 Potassium bromate-potassium bromide standard titration solution: c(⅙KBrO₃)=0.5, 0.1, 0.05 mol/L. Preparation: weigh potassium bromate 14, 2.8, 1.4 g and potassium bromide 51, 10, 5 g, dissolve in 1L water, shake well. Standardization: measure 30.00~35.00 mL potassium bromate-potassium bromide solution into an iodine flask, add 2 g potassium iodide and 5 mL hydrochloric acid solution [19%(m/m)], shake well, place in the dark for 5 min, add 30 mL water, titrate with sodium thiosulfate standard titration solution until light yellow, add 3 mL starch indicator solution (5 g/L), continue titrating until the blue color disappears, and simultaneously perform a blank test.
• 4.9 Iodine standard titration solution: c(½I₂)=0.1 mol/L. Preparation: weigh 13 g iodine and 35 g potassium iodide, dissolve in 100 mL water, dilute to 1L, shake well, store in a brown glass-stoppered bottle. Standardization: weigh 0.15 g reference arsenic trioxide previously dried in a sulfuric acid desiccator to constant weight, accurate to 0.0002 g, place in an iodine flask, dissolve with 4 mL sodium hydroxide (40 g/L), add 50 mL water, add 2 drops of phenolphthalein-ethanol indicator solution (10 g/L), neutralize with sulfuric acid solution [5%(m/m)], then add 3 g sodium bicarbonate and 3 mL starch indicator solution (5 g/L), titrate until light blue, and simultaneously perform a blank test. Comparison: measure 30.00~35.00 mL of the prepared iodine solution into an iodine flask, add 150 mL water, titrate with sodium thiosulfate standard titration solution [c(Na₂S₂O₃)=0.1 mol/L] until light yellow, add 3 mL starch indicator solution (5 g/L), continue titrating until the blue color disappears; blank test: take 250 mL water, add 0.05 mL of the prepared iodine solution and 3 mL starch indicator solution (5 g/L), titrate with sodium thiosulfate standard titration solution [c(Na₂S₂O₃)=0.1 mol/L] until the blue color disappears.
• 4.10 Potassium permanganate standard titration solution: c(⅕KMnO₄)=0.1 mol/L. Preparation: weigh 3.3 g potassium permanganate, dissolve in 1L water, slowly boil for 15 min, after cooling stand in the dark for two weeks, take the supernatant liquid and store in a brown glass-stoppered bottle. Standardization: weigh 0.2 g reference sodium oxalate dried at 105~110℃ to constant weight, accurate to 0.0002 g, dissolve in 100 mL sulfuric acid solution (sulfuric acid and water in a volume ratio of 8:92), titrate, when near the endpoint heat to 65℃, continue titrating until a pink color persists for 30 s, and simultaneously perform a blank test.
• 4.11 Disodium ethylenediaminetetraacetate (EDTA) standard titration solution: c(EDTA)=0.2, 0.1, 0.05 mol/L. Preparation: weigh disodium ethylenediaminetetraacetate 80, 40, 20 g, dissolve with heating in 1L water, shake well. Standardization: reference zinc oxide ignited at 800℃ to constant weight, 0.2 mol/L take 0.50 g, 0.1 mol/L take 0.25 g, 0.05 mol/L take 0.13 g, accurate to 0.0002 g, moisten with a small amount of water, add 2 mL hydrochloric acid solution [19%(m/m)] to dissolve, add 10 mL water, neutralize with ammonia solution [10%(m/m)] to pH 7~8, then add 10 mL ammonia-ammonium chloride buffer solution (pH~10) and about 0.1 g Eriochrome Black T indicator (7.9 strips), titrate until the color changes from purple to pure blue, and simultaneously perform a blank test. Note: The preparation of ammonia-ammonium chloride buffer solution (pH~10) is to weigh 54.0 g ammonium chloride dissolve in water, add 350 mL ammonia water, dilute to 1 L.
• 4.12 Magnesium chloride standard titration solution: c(MgCl₂)=0.1 mol/L. Preparation: weigh 21 g magnesium chloride, dissolve in 1L hydrochloric acid solution (hydrochloric acid and water in a volume ratio of 0.5:999.5), after standing for one month take the supernatant liquid for standardization. Standardization: measure 30.00~35.00 mL of the prepared magnesium chloride solution, add 70 mL water and 10 mL ammonia-ammonium chloride buffer solution (pH~10), add about 0.1 g Eriochrome Black T indicator (7.9 strips), titrate with disodium ethylenediaminetetraacetate standard titration solution [c(EDTA)=0.1 mol/L] until the color changes from purple to pure blue, and simultaneously perform a blank test.
• 4.13 Potassium thiocyanate standard titration solution: c(KCNS)=0.05 mol/L. Preparation: weigh 4.9 g potassium thiocyanate, dissolve in 1L water, shake well. Standardization: weigh 0.25 g reference silver nitrate dried in a sulfuric acid desiccator to constant weight, accurate to 0.0002 g, dissolve in 100 mL water, add 2 mL ferric ammonium sulfate indicator solution (80 g/L) and 10 mL nitric acid solution [25%(m/m)], titrate with shaking, before the endpoint shake the solution until completely clear, then continue titrating until a light brownish-red color persists for 30 s.
• 4.14 Silver nitrate standard titration solution: c(AgNO₃)=0.05 mol/L. Preparation: weigh 8.7 g silver nitrate, dissolve in 1L water, shake well, store in a brown glass-stoppered bottle. Standardization: weigh 0.1 g reference sodium chloride ignited at 500~600℃ to constant weight, accurate to 0.0002 g, dissolve in 70 mL water, add 5 mL starch indicator solution (5 g/L), titrate, near the end point add 3 drops of fluorescein indicator solution (5 g/L), continue titrating until the color changes from yellow to pink, and simultaneously perform a blank test.
• 4.15 Perchloric acid-glacial acetic acid standard titration solution: c(HClO₄)=0.1 mol/L. Preparation: pour 8.5 mL perchloric acid into 500 mL glacial acetic acid with stirring, add 20 mL acetic anhydride at room temperature, stir until uniform, after cooling dilute to 1L with glacial acetic acid, shake well. Standardization: weigh 0.6 g reference potassium hydrogen phthalate dried at 105~110℃ to constant weight, accurate to 0.0002 g, place in a dry conical flask, add 50 mL glacial acetic acid, dissolve with warming, add 4~5 drops of crystal violet-glacial acetic acid indicator solution (2 g/L), titrate until the color changes from purple to blue (slightly purple), and simultaneously perform a blank test. Note: This solution should be standardized before use, and the temperature during standardization should be the same as the temperature when using this standard titration solution.

Reference solutions (Chapter 5):

• 5.1 Potassium dichromate reference solution: c(⅙K₂Cr₂O₇)=0.2, 0.1 mol/L. Preparation: weigh reference potassium dichromate dried at 120℃ to constant weight 9.8060, 4.9030 g, accurate to 0.0002 g, dissolve with a small amount of water, transfer to a 1L volumetric flask, dilute to the mark, shake well.
• 5.2 Sodium oxalate reference solution: c(½Na₂C₂O₄)=0.1 mol/L. Preparation: weigh 6.7000 g reference sodium oxalate dried at 105~110℃ to constant weight, accurate to 0.0002 g, dissolve with a small amount of water, transfer to a 1L volumetric flask, dilute to the mark, shake well.
• 5.3 Zinc oxide reference solution: c(ZnO)=0.2, 0.05, 0.02 mol/L. Preparation: weigh reference zinc oxide ignited at 800℃ to constant weight 16.2760, 4.0690, 1.6276 g, accurate to 0.0002 g, add 20 mL hydrochloric acid solution [19%(m/m)] and 25 mL water to dissolve, transfer to a 1L volumetric flask, dilute to the mark, shake well.
• 5.4 Sodium chloride reference solution: c(NaCl)=0.1, 0.02 mol/L. Preparation: weigh reference sodium chloride ignited at 500~600℃ to constant weight 5.8445, 1.1689 g, accurate to 0.0002 g, dissolve with a small amount of water, transfer to a 1L volumetric flask, dilute to the mark, shake well.

Other solutions (Chapter 6):

• 6.1 19%, 13%, 10%, 7%, 4%(m/m) hydrochloric acid solution: measure hydrochloric acid [36%~38%(m/m)] 490(500), 325(335), 245(250), 170(170), 95(85) mL, dilute with water to 1L, shake well.
• 6.2 98.5±0.5%, 95.0±0.5%(m/m) sulfuric acid solution: 98.5±0.5% preparation is to place the bottle containing sulfuric acid [95%~98%(m/m)] in a cooling bath, slowly pour fuming sulfuric acid (fuming sulfuric acid and sulfuric acid in a 1:3 volume ratio) into the sulfuric acid, shake well, let stand for 3 d; 95.0±0.5% preparation is to measure 980 mL sulfuric acid [95%~98%(m/m)] and add to 20 mL water, shake well. Standardization: use the decrement method to weigh 0.5 g of the prepared sulfuric acid solution (accurate to 0.0002 g) and place in a conical flask containing 50 mL water, mix uniformly, after cooling add 2~3 drops of phenolphthalein-ethanol indicator solution (10 g/L), titrate with sodium hydroxide standard titration solution [c(NaOH)=0.5 mol/L] until pink.
• 6.3 26%, 20%, 18%, 9%, 5%(m/m) sulfuric acid solution: measure sulfuric acid [95%~98%(m/m)] 175(165), 130(140), 120(110), 54(55), 30(28) mL slowly inject into 700 mL water, after cooling to room temperature dilute to 1L, shake well.
• 6.4 28%, 10%, 6%, 3%, 1%(m/m) nitric acid solution: measure nitric acid [65%~68%(m/m)] 350(335), 110(135), 66(66), 32(33), 10.6(6.6) mL, dilute with water to 1L, shake well.
• 6.5 10%, 4%(m/m) ammonia solution: measure ammonia water [25%~28%(m/m)] 380(400), 155(145) mL, dilute with water to 1L, shake well.
• 6.6 12%, 1%(m/m) glacial acetic acid solution: measure glacial acetic acid [99%(m/m)] 120(120), 9.6(12) mL, dilute with water to 1L, shake well.
• 6.7 85%, 60%, 20%(V/V) ethanol solution: measure 95% ethanol 900, 630, 210 mL, dilute with water to 1L, shake well.
• 6.8 200, 100, 80, 60, 40, 20, 8, 4 g/L sodium hydroxide solution: weigh sodium hydroxide 200, 100, 80, 60, 40, 20, 8, 4 g, dissolve with an appropriate amount of water and dilute to 1L, shake well. 200, 100 g/L sodium hydroxide solution should be stored in a glass bottle lined with paraffin on the inner wall or in an alkali-resistant plastic bottle.
• 6.9 20%(m/m) sodium hydroxide saturated brine: weigh 200 g sodium hydroxide in a 1L beaker, add 800 mL water, stir with a glass rod, after complete dissolution add refined table salt until no more dissolves, store in a glass bottle lined with paraffin on the inner wall or in an alkali-resistant plastic bottle.
• 6.10 100 g/L[10%(m/V)] lead acetate solution: weigh 100 g lead acetate, add 30 mL glacial acetic acid, dilute with water to 1L, shake well. Note: “10%(m/V)” is a solution concentration unit once used in relevant standards; now 100 g/L should be used to express the concentration of this solution, the same below.
• 6.11 150 g/L[15%(m/V)] acidic cadmium sulfate solution: weigh 150 g cadmium sulfate, dissolve with a small amount of water, add to 10 mL sulfuric acid solution [26%(m/m)], transfer to a 1L volumetric flask, dilute to the mark, shake well.
• 6.12 2.5 g/L[0.25%(m/V)] ammonium vanadate solution: weigh 2.5 g ammonium metavanadate, dissolve with heating in about 300 mL water, after cooling add 20 mL nitric acid [65%~68%(m/m)], transfer to a 1L volumetric flask, dilute to the mark, shake well.
• 6.13 50 g/L[5%(m/V)] ammonium molybdate solution: weigh 50 g ammonium molybdate in a 600 mL beaker, add about 300 mL water, dissolve with heating (temperature not exceeding 60℃), after cooling transfer to a 1L volumetric flask, dilute to the mark, shake well (filter if precipitate appears).
• 6.14 50 g/L[5%(m/V)] boric acid solution: weigh 50 g boric acid, add 1L water, heat to boiling and take the supernatant liquid.
• 6.15 20 g/L[2.0%(m/V)]8- hydroxyquinoline solution: weigh 20 g 8- hydroxyquinoline, dissolve in 80~100 mL glacial acetic acid, dilute with water to 1L, shake well.
• 6.16 250 g/L[25%(m/V)] stannous chloride solution: weigh 250 g stannous chloride containing 2 water of crystallization, dissolve in 250 mL hydrochloric acid [36%~38%(m/m)], heat until completely dissolved, then dilute with water to 1L, shake well.
• 6.17 81.2 g/L(0.5 M) iodine monochloride solution: weigh 55.5 g potassium iodide in a 250 mL beaker, transfer with a small amount of water to a 1L volumetric flask, add 400 mL water, 445 mL hydrochloric acid [36%~38%(m/m)], shake to dissolve and cool to room temperature, slowly add 37.5 g potassium iodate, while shaking and cooling under a tap water faucet, until the initially formed iodine redissolves, obtaining a clear orange-red solution, after cooling to room temperature dilute to the mark, shake well. Note: Rubber stoppers are prohibited for containers holding iodine monochloride solution. Under certain conditions, iodine monochloride can react with ammonium ions to form nitrogen triiodide, which is very explosive, so iodine monochloride is absolutely prohibited from contacting ammonia or ammonium salts.
• 6.18 100 g/L[10%(m/V)] cadmium dichloride solution: weigh 100 g cadmium dichloride, add 10 mL hydrochloric acid [36%~38%(m/m)], dilute with water to 1L, shake well.
• 6.19 75 g/L(0.2 M) disodium edetate (EDTA) solution: weigh 75 g disodium edetate, transfer with a small amount of water into a 1L volumetric flask, dilute to the mark, and shake well.

Commonly used indicator solutions and indicators (Chapter 7):

• 7.1 1 g/L[0.1%(m/V)] cresol red-ethanol indicator solution: weigh 0.1 g cresol red, grind finely, dissolve in 100 mL 95% ethanol, boil under reflux in a water bath for 5 min, and while hot titrate with potassium hydroxide-ethanol solution (3 g/L) until it changes from orange-red to deep red, and upon cooling can return to orange-red.
• 7.2 10, 5, 2.5 g/L[1, 0.5, 0.25%(m/V)] starch indicator solution: weigh soluble starch 1, 0.5, 0.25 g, add 10 mL water, pour under stirring into 90 mL water, then simmer for 2 min until almost completely transparent, and use after filtration. This solution is prepared before use. If a few drops of toluene or chloroform are added during preparation, it can be used for several days.
• 7.3 20 g/L[2%(m/V)] alkali blue 6B- ethanol indicator solution: weigh 2 g alkali blue 6B, dissolve in 100 mL boiled 95% ethanol, reflux in a water bath for 1 h, and filter after cooling. If necessary, the boiled clear filtrate should be neutralized with potassium hydroxide-ethanol solution (3 g/L) or hydrochloric acid-ethanol solution until the addition of 1~2 drops of potassium hydroxide-ethanol solution (3 g/L) can make the alkali blue 6B- ethanol indicator solution change from blue to light red, and upon cooling can return to blue. Note: The preparation of hydrochloric acid-ethanol solution is to dilute 4.5 mL hydrochloric acid [36%~38%(m/m)] with ethanol to 1L.
• 7.4 1 g/L[0.1%(m/V)] bromothymol blue-ethanol indicator solution: weigh 0.1 g bromothymol blue, dissolve in 3.2 mL potassium hydroxide-ethanol solution (3 g/L), then dilute with 20% ethanol solution to 100 mL, and shake well.
• 7.5 bromocresol green-methyl red mixed indicator solution: measure 3 volume of the prepared bromocresol green-ethanol solution (1 g/L) and 1 volume of methyl red-ethanol solution (2 g/L), and shake well.
• 7.6 xylenol orange indicator: weigh 1 g xylenol orange and 100 g sodium chloride, mix and grind finely, then store in a ground-glass stoppered bottle.
• 7.7 80 g/L ferric ammonium sulfate indicator solution: weigh 8.0 g ferric ammonium sulfate, dissolve in water (add a few drops of sulfuric acid), and dilute to 100 mL.
• 7.8 5 g/L[0.5%(m/V)] eriochrome black T- ethanol indicator solution: weigh 0.5 g eriochrome black T and 2.0 g hydroxylamine hydrochloride, dissolve in ethanol, dilute with ethanol to 100 mL, and shake well. The validity period of this solution is 7 d.
• 7.9 eriochrome black T indicator: weigh 1 g eriochrome black T and 100 g sodium chloride, mix and grind finely, then store in a ground-glass stoppered bottle.
• 7.10 calcein indicator: weigh 1 g calcein indicator and 100 g sodium chloride, mix and grind finely, then store in a ground-glass stoppered bottle (shelf life of half a year).

5. Instruments and Equipment

• 3.4 The weights, burettes, volumetric flasks, and pipettes, etc. of the analytical balance used in this standard shall be periodically verified according to the requirements of metrological verification regulations.
• Other instruments and equipment: not provided in the available source.

6. Recommended Operating Conditions

• 3.11 Validity period of standard titration solutions and reference solutions at room temperature (15~25℃): potassium hydroxide-ethanol (or isopropanol) standard titration solution and hydrochloric acid-ethanol (or isopropanol) standard titration solution are 15 d, and other standard titration solutions and reference solutions are two months.
• 3.10 Whenever both the "standardization" and "comparison" methods are specified for standardizing concentration, in case of dispute, the standardization method shall prevail.
• 3.7 When standardizing the concentration of a standard titration solution, the difference between the concentration value of a single standardization and the arithmetic mean shall not exceed 0.2% of the arithmetic mean. The arithmetic mean of at least three standardization results shall be taken as the actual concentration of the standard titration solution.
• For other operating conditions, see the respective clauses.

7. Sampling and Sample Preparation

• not provided in the available source (this standard is a method for preparing reagent solutions and does not involve sample sampling and sample preparation).

8. Analytical Procedure

• See Section 4 for the preparation, standardization, and comparison procedures of each standard titration solution, Section 5 for the preparation procedures of reference solutions, Section 6 for the preparation procedures of other solutions, and Section 7 for the preparation procedures of indicator solutions and indicators.

9. Qualitative and Quantitative Determination and Calculation Formulas

• 4.1.2.2 Hydrochloric acid standard titration solution: c(HCl) = m / [(V₁ - V₀) × 0.05299] (Formula 1). Where: m— mass of anhydrous sodium carbonate, g; V₁—amount of hydrochloric acid solution used, mL; V₀—amount of hydrochloric acid solution used in the blank test, mL; 0.05299— and 1.00 mL mass of anhydrous sodium carbonate, expressed in grams, equivalent to the hydrochloric acid standard titration solution [c(HCl)=1.000 mol/L].
• 4.1.3.2 Hydrochloric acid standard titration solution (comparison): c(HCl) = V₁·c₁ / V (Formula 2). Where: V₁—amount of sodium hydroxide standard titration solution used, mL; c₁—actual concentration of the sodium hydroxide standard titration solution, mol/L; V— amount of hydrochloric acid solution used, mL.
• 4.2.2.2 Hydrochloric acid-ethanol (or isopropanol) standard titration solution: c(HCl) = m / [(V₁ - V₀) × 0.05299] (Formula 3). The symbols in the formula are the same as in Formula 1, and V₁ is the amount of hydrochloric acid-ethanol (or isopropanol) solution used.
• 4.2.3.2 Hydrochloric acid-ethanol (or isopropanol) standard titration solution (comparison): c(HCl) = V₁·c₁ / V (Formula 4). Where: V₁—amount of sodium hydroxide standard titration solution used, mL; c₁—actual concentration of the sodium hydroxide standard titration solution, mol/L; V— amount of hydrochloric acid-ethanol (or isopropanol) solution used, mL.
• 4.3.2.2 Sulfuric acid standard titration solution: c(½H₂SO₄) = m / [(V₁ - V₀) × 0.05299] (Formula 5). Where: m— mass of anhydrous sodium carbonate, g; V₁—amount of sulfuric acid solution used, mL; V₀—amount of sulfuric acid solution used in the blank test, mL; 0.05299— and 1.00 mL mass of anhydrous sodium carbonate, expressed in grams, equivalent to the sulfuric acid standard titration solution [c(½H₂SO₄)=1.000 mol/L].
• 4.3.3.2 Sulfuric acid standard titration solution (comparison): c(½H₂SO₄) = V₁·c₁ / V (Formula 6). Where: V₁—amount of sodium hydroxide standard titration solution used, mL; c₁—actual concentration of the sodium hydroxide standard titration solution, mol/L; V— amount of sulfuric acid solution used, mL.
• 4.4.2.2 Sodium hydroxide standard titration solution: c(NaOH) = m / [(V₁ - V₀) × 0.2042] (Formula 7). Where: m— mass of potassium hydrogen phthalate, g; V₁—amount of sodium hydroxide solution used, mL; V₀—amount of sodium hydroxide solution used in the blank test, mL; 0.2042— and 1.00 mL mass of potassium hydrogen phthalate, expressed in grams, equivalent to the sodium hydroxide standard titration solution [c(NaOH)=1.000 mol/L].
• 4.4.3.2 Sodium hydroxide standard titration solution (comparison): c(NaOH) = V₁·c₁ / V (Formula 8). Where: V₁—amount of hydrochloric acid standard titration solution used, mL; c₁—actual concentration of the hydrochloric acid standard titration solution, mol/L; V— amount of sodium hydroxide solution used, mL.
• 4.5.2.2 Potassium hydroxide standard titration solution: c(KOH) = m / [(V₁ - V₀) × 0.2042] (Formula 9). Where: m— mass of potassium hydrogen phthalate, g; V₁—amount of potassium hydroxide solution used, mL; V₀—amount of potassium hydroxide solution used in the blank test, mL; 0.2042— and 1.00 mL mass of potassium hydrogen phthalate, expressed in grams, equivalent to the potassium hydroxide standard titration solution [c(KOH)=1.000 mol/L].
• 4.5.3.2 Potassium hydroxide standard titration solution (comparison): c(KOH) = V₁·c₁ / V (Formula 10). Where: V₁—amount of hydrochloric acid standard titration solution used, mL; c₁—actual concentration of the hydrochloric acid standard titration solution, mol/L; V— amount of potassium hydroxide solution used, mL.
• 4.6.2.2 Potassium hydroxide-ethanol (or isopropanol) standard titration solution: c(KOH) = m / [(V₁ - V₀) × 0.2042] (Equation 11). Where: m— mass of potassium hydrogen phthalate, g; V₁—volume of potassium hydroxide-ethanol (or isopropanol) solution used, mL; V₀—volume of potassium hydroxide-ethanol (or isopropanol) solution used in the blank test, mL; 0.2042— and 1.00 mL mass of potassium hydrogen phthalate, expressed in grams, equivalent to the potassium hydroxide-ethanol (or isopropanol) standard titration solution [c(KOH)=1.000 mol/L].
• 4.7.2.2 Sodium thiosulfate standard titration solution: c(Na₂S₂O₃) = m / [(V₁ - V₀) × 0.04903] (Equation 12). Where: m— mass of potassium dichromate, g; V₁—volume of sodium thiosulfate solution used, mL; V₀—volume of sodium thiosulfate solution used in the blank test, mL; 0.04903— and 1.00 mL mass of potassium dichromate, expressed in grams, equivalent to the sodium thiosulfate standard titration solution [c(Na₂S₂O₃)=1.000 mol/L].
• 4.8.2.2 Potassium bromate-potassium bromide standard titration solution: c(⅙KBrO₃) = (V₁ - V₀)·c₁ / V (Equation 13). Where: V₁—volume of sodium thiosulfate standard titration solution used, mL; V₀—volume of sodium thiosulfate standard titration solution used in the blank test, mL; c₁—actual concentration of the sodium thiosulfate standard titration solution, mol/L; V— volume of potassium bromate-potassium bromide solution used, mL.
• 4.9.2.2 Iodine standard titration solution: c(½I₂) = m / [(V₁ - V₀) × 0.04946] (Equation 14). Where: m— mass of arsenic trioxide, g; V₁—volume of iodine solution used, mL; V₀—volume of iodine solution used in the blank test, mL; 0.04946— and 1.00 mL mass of arsenic trioxide, expressed in grams, equivalent to the iodine standard titration solution [c(½I₂)=1.000 mol/L].
• 4.9.3.2 Iodine standard titration solution (comparative): c(½I₂) = (V₁ - V₀)·c₁ / (V - 0.05) (Equation 15). Where: V₁—volume of sodium thiosulfate standard titration solution used, mL; V₀—volume of sodium thiosulfate standard titration solution used in the blank test, mL; c₁—actual concentration of the sodium thiosulfate standard titration solution, mol/L; V— volume of iodine solution used, mL; 0.05— volume of iodine solution added in the blank test, mL.
• 4.10.2.2 Potassium permanganate standard titration solution: c(⅕KMnO