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    Home > Chemicals Industry > Chemical Technology > Industrial Acrylonitrile—Determination of Iron and Copper Content Spectrophotometric Method (3)

    Industrial Acrylonitrile—Determination of Iron and Copper Content Spectrophotometric Method (3)

    • Last Update: 2022-01-11
    • Source: Internet
    • Author: User
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    7 Determination of copper content

    7.


    The sample is evaporated to dryness and digested with mixed acid to remove organic matter.


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    7.
    3.
    6 Volumetric flasks: 25mL, 100mL, 500mL, 1000mL;

    7.
    3.
    7 Pipette: 5mL, 10mL;

    7.
    3.
    8 Measuring cylinder: 250mL;

    7.
    3.
    9 Graduation straw: 5mL;

    7.
    3.
    10 Watch glass: 975mm;

    7.
    3.
    11 Quantitative filter paper: medium speed;

    7.
    3.
    12 Heating plate: explosion-proof type
    .

    7.
    4 Analysis steps

    7.
    4.
    1 Drawing of copper standard curve

    Before analysis, all glassware should be washed with hot nitric acid solution (7.
    2.
    7) and rinsed with water to remove traces of stained copper
    .

    7.
    4.
    1.
    1 Prepare 0.
    1mg/mL copper ion standard solution according to GB/T602
    .
    Accurately draw 5mL of this solution, transfer it into a 100mL volumetric flask, and dilute to the mark with water to obtain a 5ug/mL copper ion standard solution
    .
    And stored in a polyethylene reagent bottle, the shelf life is one month
    .

    7.
    4.
    1.
    2 Take 5 50mL beakers and add 1.
    0mL, 2.
    0mL, 3.
    0mL, 4.
    0mL and 5.
    0mL of the above-mentioned standard solution in sequence (the copper content is 5.
    0ug, 10.
    0ug: 15.
    0ug, 20.
    0ug, 25.
    0ug) , Dilute with water to about 10mL, and then add 5mL ammonium citrate (7.
    2.
    5) solution to each, adjust each solution with ammonia water to pH=9.
    1+0.
    1.
    Transfer these solutions to the corresponding 25mL volumetric flask quantitatively, and then Add 1 mL of DDTC (7.
    2.
    6) solution to each, dilute to the mark with water, broadcast well, and let stand at room temperature for 5 min
    .
    At the same time, take another 50mL beaker and prepare a standard blank solution according to the same steps except that the copper standard solution is not added
    .

    7.
    4.
    1.
    3 Measure the absorbance of the solution with a 3cm absorption cell at a wavelength of 448nm, using water as a reference
    .
    Take the copper content (ug) as the abscissa and the net absorbance (deduct the absorbance of the blank solution) as the ordinate to draw a standard curve
    .

    7.
    4.
    2 Determination of copper in the sample

    7.
    4.
    2.
    1 Accurately measure 100mL of the sample to be tested (5.
    2) in a 250mL beaker, cover with a glass watch glass, evaporate to dryness on a water bath, cool, add 3mL of mixed acid (7.
    2.
    4), and heat on a hot plate Bring to boiling, until white smoke emerges, and concentrate to the solution volume of about (1 ~ 2) mL, and cool
    .
    If the residue is colored, the above acid treatment must be repeated, or 0.
    2mL of perchloric acid must be carefully added to oxidize, heat, and smoke until the remaining (1~2)mL solution (the above process should be performed in a fume hood)
    .
    After cooling, slowly add 5 mL of water to the beaker to decompose the residue
    .
    Quantitatively transfer the solution into a 50mL beaker to keep the total volume at about 10mL.
    Then add 5mL of ammonium citrate (7.
    2.
    5) solution, and adjust the solution to pH=9+0.
    1 with ammonia
    .
    Quantitatively transfer these solutions to the corresponding 25mL volumetric flask, then add 1mL DDTC (7.
    2.
    6) solution, dilute to the mark with water, shake well, and let stand at room temperature for 5 minutes
    .
    At the same time, take another 50 mL beaker, and prepare the sample blank solution according to the same steps as above except that the acrylonitrile sample is not added, evaporated to dryness, and cooled
    .

    7.
    4.
    2.
    2 Measure the absorbance of the solution with a 3cm absorption cell at a wavelength of 448nm, using water as a reference
    .
    According to the net absorbance value of the sample, check the copper content (ug) on ​​the standard curve
    .

     

     

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