Industrial cobalt acetate (3)

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Weigh 2g of the sample (accurate to 0.

Take 20mL of B solution, place it in a 100mL colorimetric tube, add 1mL of silver nitrate solution, add water to 50mL, mix well, and place for 15min

Standard turbidity solution: Take 20mL of B solution, place it in a 100mL beaker, add 1mL of silver nitrate solution, heat it on a boiling water bath for 10 minutes, after cooling, filter it in a 100mL colorimetric tube

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Weigh 1g of the sample (accurate to 0.
01g), dissolve it in 10mL of water, add 10ml of sodium hydroxide solution, heat it on a boiling water bath for 10min, cool and add water to 100mL, and filter
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Take 10mL, add 1mL sodium chloride solution, 1mL indigo sodium disulfonate solution, drop 10mL sulfuric acid within 10s-15s under shaking, leave it for 10min, the blue color should not be lighter than the standard colorimetric solution
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The standard colorimetric solution is to take the nitrate standard solution (0.
5mL for the excellent product; 0.
8mL for the first-class product and qualified product), add water to 10mL, and process the same volume of the above-mentioned filtered sample solution at the same time
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6 Determination of iron, copper and nickel

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6.
1 Method summary

In an acidic medium, the sample solution is analyzed with an atomic absorption spectrophotometer with an air acetylene flame
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The photometric curve method is used to calculate the element content
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6.
2 Reagents and solutions

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6.
2.
1 Hydrochloric acid solution: 1+2
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6.
2.
2 Iron standard solution: 1mL solution contains 0.
1mg Fe
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6.
2.
3 Copper standard solution: 1mL solution contains 0.
1mg Cu
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6.
2.
4 Nickel standard solution: 1mL solution contains 0.
1mg Ni
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6.
3 Apparatus and equipment

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6.
3.
1 Atomic absorption spectrophotometer: wavelength range 190nm～900nm
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6.
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2 Hollow cathode lamps of iron, copper, nickel, or multi-element hollow cathode lamps
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3 Flame: acetylene-air
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4 Wavelength: iron 248.
3nm; copper 324.
8nm; nickel 232.
0nm
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6.
4 Analysis steps

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6.
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1 Preparation of sample solution

Determination of iron and copper: Weigh 1g sample (accurate to 0.
001g), dissolve it in water, add 2ml hydrochloric acid solution, quantitatively transfer it to a 25mL volumetric flask, dilute to the mark with water, and shake well
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Determine nickel: Weigh 1g sample (accurate to 0.
001g), dissolve it in water, add 2mL hydrochloric acid solution, transfer quantitatively to a 100mL volumetric flask, dilute to the mark with water, and shake well
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6.
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2 Drawing of standard curve

Take 1.
00mL, 2.
00mL, 4.
00mL, 8.
00mL of iron and copper standard solutions respectively, and take 2.
00mL, 4.
00mL, 6.
00mL, 8.
00mL of nickel standard solutions and place them in 100mL volumetric flasks, dilute to the mark with water, and shake well.
, Make a standard series of solutions
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Set the operating conditions of the atomic absorption spectrophotometer according to the instrument manual, adjust the wavelength according to 4.
6.
3.
4, introduce the standard series of solutions to the atomic absorption spectrophotometer, adjust the zero with water, measure the absorbance, and draw a standard curve of absorbance versus concentration
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6.
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3 Determination of samples

The sample solution is introduced into the atomic absorption spectrophotometer, the absorbance is measured, and the concentration of the element is found from the standard curve
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5 Expression of analysis results

The content (X _i ) of an element expressed in mass percentage is calculated according to formula (3):

Where: V—volume of sample, mL;

c _i —the concentration of an element in the sample, mg/L;

m _i —the mass of the sample, g
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6 Allowable difference

Take the arithmetic mean of the two parallel determination results as the determination result
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The relative deviation of the two parallel determination results shall not be greater than 20%
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