GB 6549-2011Potassium chloride (English PDF)

5.1 Determination of potassium oxide content of potassium tetraphenylborate gravimetric method

5.1.1 Method summary

After the sample was dissolved in water, heating under alkaline conditions to eliminate interference in a sample of ammonium ions, added disodium edetate eliminate interference points Analysis of the results of other cations. Potassium and sodium tetraphenylborate reaction of potassium tetraphenylborate precipitate was filtered, dried and weighed.

5.1.2 Reagents and solutions

5.1.2.1 sodium hydroxide solution.200g/L.

5.1.2.2 disodium ethylenediaminetetraacetate (EDTA) solution. 40g/L.

5.1.2.3 sodium tetraphenylborate solution. 30g/L. Weigh 30g of sodium tetraphenylborate [NaB (C6H5) 4], was dissolved in 980mL of water, add 4mL hydrogen Sodium hydroxide solution, 20mL magnesium chloride solution (100g/LMgCl2 · 6H2O), stirred for 15min, filtered before use.

5.1.2.4 sodium tetraphenylborate washing solution. 1g/L. Filtrate with 30g/L of sodium tetraphenylborate solution formulated by 130.

5.1.2.5 phenolphthalein indicator solution. 5g/L. 0.5g phenolphthalein dissolved in 100mL of ethanol.

5.1.3 Instruments

5.1.3.1 Glass filter crucible. the 4th, 25mL or 30mL.

5.1.3.2 oven. adjustable at 120 °C ± 2 °C.

5.1.4 Analysis of step

5.1.4.1 Preparation of test solution

Weigh about 5g sample, to the nearest 0.001g, placed in 250mL beaker, add 100mL of water, stirring constantly heated micro-boiling 5min, removed, cooled to room temperature and transferred to 500mL volumetric flask, dilute to the mark, shake. This is the solution A.

Dry solution was filtered A, a small amount of initial filtrate was discarded, the filtrate Pipette 25.0mL in 250mL volumetric flask, dilute to the mark, shake uniform. This is the solution B.

5.1.4.2 Determination

Pipette 50.0mL of solution B in 250mL beaker, 10mLEDTA solution, 2 to 3 drops of phenolphthalein indicator solution, with stirring Sodium hydroxide solution was added dropwise to an excess of red appeared and 1mL. Heating boil 5min, a solution remains red, volume remains 50mL about.

Remove the beaker with a little water to wash the cup wall. Under constant stirring, slowly dropped 12mL sodium tetraphenylborate solution and continue stirring 1min, in Water rapidly cooled to room temperature, placed 10min.

Previously used 120 °C drying to constant weight of glass suction filter crucible. First suction supernatant with sodium tetraphenylborate was washed with dumping the precipitate was washed slope method 4 to 5 times the precipitate to the filter and transferred until the transfer complete precipitation continued for 3 to 4 times with washing liquid in the filter, each wash was about 5mL use. Finally, the precipitate was washed with water twice, each time with water to about 5mL.

The precipitate containing filter placed in an oven at 120 °C drying 90min. Removed, placed in a desiccator to cool to room temperature, and weighed.

5.1.5 Calculation Results

Potassium oxide (K2O) content w1 mass fraction (%) expressed by the formula (1).

w1 = m1 × 0.1314m × 25/500 × 50/250 × 100 × 100-w2 = M1 × 1314m × 100-w2 (1) where.

m1 --- potassium tetraphenylborate precipitate mass value in grams (g);

Numerical m --- sample mass, in grams (g);

w2 --- in a sample of water mass fraction,%;

.1314 --- Tetraphenylboron quality potassium hydroxide in terms of the value of the quality factor.

Calculation result to two decimal places, take the arithmetic mean of the parallel determination results for the final determination.

5.1.6 Allowable difference

Parallel determination results of the absolute difference should be less than 0.38%.

5.2 Determination of Moisture

5.2.1 Method summary

Sample at 105 °C ± 2 °C oven drying to reduce moisture content is the quality.

5.2.2 Instruments

5.2.2.1 said vials. with ground glass lid, flat, a diameter of about 60mm, height of about 30mm.

5.2.2.2 oven. adjustable at 105 °C ± 2 °C.

5.2.2.3 dryer. Load the appropriate drying agent, such as discoloration of silica gel.

5.2.3 Analysis of step

Weigh about 5g sample, to the nearest 0.001g, is placed in a pre-dried to a constant weight of 105 °C ± 2 °C weighing bottle, gently shake weighing Bottle, so that the sample is uniformly tiled weighing bottle, open weighing bottle, be placed in 105 °C ± 2 °C oven 120min. Remove say Flask, capped, into the dryer to cool to room temperature and weighed.

5.2.4 Calculation Results

Water (H2O) content w2 mass fraction (%) expressed by the formula (2).

w2 = m1-m2m × 100

Where.

m1 --- said vials and sample values before drying mass in grams (g);

m2 --- said vials and sample mass after drying value in units of grams (g);

Numerical m --- sample mass, in grams (g).

Calculation result to two decimal places, take the arithmetic mean of the parallel determination results for the final determination.

5.2.5 Allowable difference

When the content is less than or equal to 4.00%, the absolute difference should be less than 0.20%; when the content is more than 4.00%, the absolute difference should be less than 0.30%.

5.3 Determination of calcium and magnesium content

5.3.1 Flame Atomic Absorption Spectrometry

The water test should be consistent with GB/T 6682 in two water specifications.

5.3.1.1 Method summary

Sample was dissolved in water, adding lanthanum chloride eliminate interfering ions, in hydrochloric acid medium, using air - acetylene flame to flame atomic Absorption spectrometer wavelength absorbance was measured at 422.7nm and 285.2nm to work curve method determined calcium and magnesium.

5.3.1.2 Reagents and solutions

5.3.1.2.1 hydrochloric acid solution. 11.

5.3.1.2.2 KCl. 10g/L.

5.3.1.2.3 lanthanum chloride solution. 100g/L.

5.3.1.2.4 calcium standard solution. 1.00mg/mL. Weigh 2.4972g advance at 105 °C ~ 110 °C drying 1h and placed in the dryer Cooled to room temperature and calcium carbonate (purity reagents), placed in 250mL beaker, add 20mL water, hydrochloric acid solution was added dropwise until complete dissolution, Excess 10mL. Heated to boiling, to make carbon dioxide flooding, remove the cooled to room temperature and transferred to 1000mL volumetric flask, dilute to the mark with water, shake uniform. The solution calcium (Ca) concentration of 1.00mg/mL.

5.3.1.2.5 calcium standard solution. 100µg/mL. Pipette 100.0mL calcium standard solution (5.3.1.2.4) in 1000mL volumetric flask Diluted with water to the mark. The solution calcium (Ca) concentration of 100µg/mL.

5.3.1.2.6 Magnesium standard solution. 1.00mg/mL. Weigh 1.6583g previously burned 1h at 900 °C and placed in the dryer to cool to Room temperature magnesium oxide (high purity reagents), placed in 250mL beaker, add 20mL water, 10mL hydrochloric acid solution, micro-heat until completely dissolved. cool down to room temperature and transferred to 1000mL volumetric flask, dilute to the mark, shake. This solution was magnesium (Mg) concentration of 1.00mg/mL.

5.3.1.2.7 Magnesium Standard solution. 50µg/mL. Pipette 50.0mL magnesium standard solution (5.3.1.2.6) in 1000mL volumetric flask, Diluted with water to the mark. This solution was magnesium (Mg) concentration of 50µg/mL.

5.3.1.3 Instruments

Flame atomic absorption spectrometer. shall comply with GB/T 9723's.

5.3.1.4 Analysis step

5.3.1.4.1 Preparation of the test solution

Table 2 Sample Weigh, to the nearest 0.001g, placed in 250mL beaker, add 100mL water, stirring constantly heated micro-boiling

5min, remove the cooled to room temperature and transferred to 250mL volumetric flask, dilute to the mark with water, shake dry filter, this is the test solution C.

Table 2 above test solution was pipetted C in 100mL volumetric flask, was added a solution of lanthanum chloride 10mL, 4mL dilute hydrochloric acid solution, washed with water

Release to the mark. Blank test solution prepared simultaneously.

Table 2 sample weight and volume of the test solutions Pipette

Calcium or magnesium content /% sample weight/g Pipette Volume/mL Calcium and magnesium 0.4 ~ 1 1.0 20.0 10.0

5.3.1.4.2 Photometry

Flame atomic absorption spectrometer with an air - acetylene flame, zero water, measured in the test solution and the blank at wavelength 422.7nm Calcium test solution absorbance by subtracting the absorbance of the test solution absorbance of the blank test solution, corresponding calcium isolated from the working curve Numerical mass concentration; measuring test solution and the blank test solution of magnesium absorbance at a wavelength at 285.2nm, with the test solution absorbance Subtract the absorbance of the blank test solution, check out the value of the corresponding concentration of magnesium from the working curve.

5.3.1.4.3 Draw the curve

Pipette respectively 0.0mL, 1.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL calcium standard solution (5.3.1.2.5) and magnesium standard solution Solution (5.3.1.2.7), correspondence, placed in a 100mL flask, add 10mL potassium chloride solution, lanthanum chloride solution and 10mL 4mL dilute hydrochloric acid solution, washed with water to the mark. This series calcium concentration of 0.0µg/mL, 1.0µg/mL, 2.0µg/mL, 4.0µg/mL, 6.0µg/mL, 8.0µg/mL, a magnesium concentration of 0.0µg/mL, 0.5µg/mL, 1.0µg/mL, 2.0µg/mL, 3.0µg/mL, 4.0µg/mL. The absorbance was measured under the same conditions and the absorbance of the test solution and minus zero concentration of the solution, calcium or magnesium the amount of concentration as abscissa and ordinate corresponding absorbance, drawing working curve.

5.3.1.5 Calculation Results

5.3.1.5.1 calcium (Ca) content w3 mass fraction (%) expressed by the formula (3) Calculated.

w3 = rho × 100 × 10

m × V/250 × 100 ×

100-w2

Where.

Value from the working curve rho --- Richard calcium mass concentration, in micrograms per milliliter (µg/mL);

Numerical m --- sample mass, in grams (g);

V --- Pipette Numerical Test solution volume in milliliters (mL);

w2 --- in a sample of water mass fraction,%.

Calculation result to two decimal places, take the arithmetic mean of the parallel determination results for the final determination.

5.3.1.5.2 magnesium (Mg) content w4 mass fraction (%) expressed by the formula (4) Calculated.

w4 = rho × 100 × 10

m × V/250 × 100 ×

100-w2

Where.

Value from the working curve rho --- Richard magnesium mass concentration, in micrograms per milliliter (µg/mL);

Numerical m --- sample mass, in grams (g);

V --- Pipette Numerical Test solution volume in milliliters (mL);

w2 --- in a sample of water mass fraction,%.

Calculation result to two decimal places, take the arithmetic mean of the parallel determination results for the final determination.

5.3.1.6 Allowable difference

When calcium or magnesium content of less than 0.20%, the absolute difference should be less than 0.02%; the content is 0.20% to 1.00%, the absolute difference should be less than 0.04%.

5.3.2 EDTA volumetric method

5.3.2.1 Method summary

Sample was dissolved in water at pH > 12 conditions, the addition of calcium acid indicator, titration with EDTA standard titration solution of calcium; at pH = 10, the Join chrome black T indicator, titration with EDTA standard solution titration, calcium, magnesium alloy amount to obtain the subtraction magnesium content.

5.3.2.2 Reagents and solutions

5.3.2.2.1 ammonia solution. 11.

5.3.2.2.2 sodium hydroxide solution. 100g/L.

5.3.2.2.3 hydrogen peroxide solution. 110. With 30% hydrogen peroxide formulation.

5.3.2.2.4 triethanolamine solution. 13.

5.3.2.2.5 ammonia - ammonium chloride buffer solution (pH = 10) was weighed 67.5g of ammonium chloride dissolved in water, aqueous ammonia was added 570mL, diluted with water to 1000mL, and mix.

5.3.2.2.6 disodium edetate (EDTA) standard titration solution. c (EDTA) = 0.02mol/L. Preparation and Calibration Press HG/T 2843 execution.

5.3.2.2.7 calcium acid indicator. Weigh 0.2g of calcium acid indicator [2-hydroxy-1- (2-carboxy-4-sulfonic acid 1-naphthyl) azo-3-naphthoyl Acid] and 10g of sodium chloride by 110 °C dried, placed in a mortar and grind to a fine powder, stored in a brown bottle grinding mouth, into the dryer set aside.

5.3.2.2.8 chrome black T indicator solution. 5g/L. Weigh 0.5g chrome black T, dissolved in 100mL triethanolamine solution (5.3.2.2.4) in.

5.3.2.3 Analysis step

5.3.2.3.1 Preparation of the test solution

Table 3. Weigh sample to the nearest 0.001g, placed in 400mL beaker, add 150mL of hot water, stirring add 4 to 5 drops of peroxide

Hydrogen solution, heated to a boil without small bubbles (about 5min), remove the cooled to room temperature and transferred to 200mL volumetric flask, dilute to the mark, Shake well.

5.3.2.3.2 Determination of calcium content

Table 3 Pipette test solution in 250mL beaker, dilute with water to about 100mL, was added 5mL triethanolamine solution, hydroxide

Sodium solution was adjusted to pH > 12, calcium acid indicator a little, stir well, titration with EDTA standard solution titration to the solution from pure pale burgundy Blue end.

5.3.2.3.3 Determination of magnesium content

Table 3 Pipette test solution in 250mL beaker, dilute with water to about 100mL, was added 5mL triethanolamine solution, adding 5mL

Ammonia - ammonium chloride buffer solution and 2 drops of chrome black T indicator solution, stir, titration with EDTA standard solution titration to the solution from pale blue-burgundy Color is the end.

5.3.2.3.4 Blank test

Determination of required sample and determination of calcium and magnesium content in the blank test at the same time.

Table 3 sample weight and volume of the test solutions Pipette

Calcium or magnesium content /% sample weight/g Pipette volume/mL 0.5 to 1.0 5 20.0

5.3.2.4 Calculation Results

5.3.2.4.1 calcium (Ca) content w5 mass fraction (%) expressed by the formula (5) Calculated.

w5 = c ×

(V2-V1) × M × 10-3

m × V/200 × 100 ×

100-w2

(V2-V1) × 4.008

m × V/200 ×

100-w2

Where.

The exact value of c --- EDTA standard titration solution, expressed in moles per liter (mol/L);

Value V2 --- EDTA standard titration solution of calcium titration volume in milliliters (mL);

Value V1 --- EDTA standard titration solution of calcium titration blank test solution volume in milliliters (mL);

V --- Pipette Numerical Test solution volume in milliliters (mL);

Numerical m --- sample mass, in grams (g);

w2 --- in a sample of water mass fraction,%;

--- The M values of the molar mass of calcium (Ca), in units of grams per mole (g/mol) (M = 40.08).

Calculation result to two decimal places, take the arithmetic mean of the parallel determination results for the final determination.

5.3.2.4.2 magnesium (Mg) content w6 mass fraction (%) expressed by the formula (6) Calculated.

w6 = c ×

[(V4-V3) - (V2-V1)] × M × 10-3 m × V/200 × 100 × 100-w2 = C × [(V4-V3) - (V2-V1)] × 2.430 m × V/200 × 100-w2 (6) where.

The exact value of c --- EDTA standard titration solution, expressed in moles per liter (mol/L);

V4 --- numerical EDTA standard titration solution titrate the amount of calcium and magnesium combined volume in milliliters (mL);

V3 --- EDTA standard titration solution titrate the amount of calcium and magnesium combined value of the blank test solution volume in milliliters (mL);

Value V2 --- EDTA standard titration solution of calcium titration volume in milliliters (mL);

Value V1 --- EDTA standard titration solution of calcium titration blank test solution volume in milliliters (mL);

V --- learn the value of the test solution volume in milliliters (mL);

Numerical m --- sample mass, in grams (g);

w2 --- in a sample of water mass fraction,%;

--- The M values of the molar mass of magnesium (Mg), in units of grams per mole (g/mol) (M = 24.30).

Calculation result to two decimal places, take the arithmetic mean of the parallel determination results for the final determination.

5.3.2.5 Allowable difference

When calcium or magnesium content of less than 0.20%, the absolute difference should be less than 0.02%; the content is 0.20% to 1.00%, the absolute difference should not Greater than 0.04 percent.

5.4 Sodium chloride content - Flame emission spectrophotometric method

The water test should be consistent with GB/T 6682 in two water specifications.

5.4.1 Method summary

Sample was dissolved in water, flame intensity excited sodium atoms, 589nm spectral intensity of the standard solution produced emitted contrast, seek the content of sodium chloride.

5.4.2 Reagents and solutions

5.4.2.1 KCl. 90mg/mL.

5.4.2.2 sodium standard solution. 1.0mg/mL. Weigh pre-dried at 400 °C 2.5421g of sodium chloride (reference reagent), dissolved in Water and transferred to 1000mL volumetric flask, dilute to the mark, shake. This solution of sodium (Na) concentration of 1.00mg/mL.

5.4.3 Instruments

Flame spectrophotometer.

5.4.4 Analysis of step

5.4.4.1 Preparation of test solution

Weigh about 1g sample, accurate to 0.0001g, placed in 250mL beaker, add about 50mL of water, stirring constantly heated micro Boiling 5min, remove the cooled to room temperature and transferred to 500mL volumetric flask, dilute with water to the mark.

5.4.4.2 Photometry

5.4.4.2.1 Preliminary measurements

Dry filtration test solution, discard a small amount of initial filtrate. Pipette about 50mL in 50mL beaker filtrate, according to a flame spectrophotometer Predetermined operation of the radiation intensity measurement sodium spectrum. Isolated from the working curve test solution approximate sodium content.

5.4.4.2.2 Draw the curve

Pipette 0.0mL, 5.0mL, 10.0mL, 15.0mL, 20.0mL, 25.0mL sodium standard solution were injected into a 500mL Flask, each added 10.0mL potassium chloride solution, diluted with water to the mark. This series of sodium 0.0mg, 5.0mg, 10.0mg, 15.0mg, 20.0mg, 25.0mg. Pipette solution of approximately 50mL in 50mL beaker, according to the provisions of spectral flame photometric analyzer operation Measuring the intensity of the radiation spectrum of sodium. Sodium concentration as abscissa, the corresponding radiation intensity as the ordinate, drawing working curve.

5.4.4.2.3 Accurately measure insertion method

According to the content of the preliminary measurement test solution of sodium prepare two similar concentrations of sodium standard solution, the content of the test solution of sodium just in the middle, and then press the flame spectrophotometers predetermined operation of the radiation intensity measurement sodium spectrum.

5.4.5 Calculation Results

5.4.5.1 sodium (Na) mass m0 (mg) according to equation (7) Calculated.

m0 = m1 (m2-m1) E0-E1E2-E1 (7) where.

Value m1 --- low concentration of sodium in the quality standard solution, in milligrams (mg);

Numerical m2 --- high concentration of standard solution of sodium mass, in milligrams (mg);

E1 --- measurements of low concentration of the standard solution, in micrograms per milliliter (µg/mL);

E2 --- measured value of the high concentration of t...