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    Home > Chemicals Industry > Chemical Technology > Solid Waste—Determination of Polycyclic Aromatic Hydrocarbons—Liquid Chromatography (1)

    Solid Waste—Determination of Polycyclic Aromatic Hydrocarbons—Liquid Chromatography (1)

    • Last Update: 2022-03-10
    • Source: Internet
    • Author: User
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    1.


    This method is suitable for naphthalene, acenaphthylene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k) in solid waste and its leaching solution.


    Second, the principle of the method

    The polycyclic aromatic hydrocarbons in the solid waste or its leaching liquid are extracted with organic solvents , and the extracts are concentrated and purified, and then separated by high performance liquid chromatograph, and measured by ultraviolet/fluorescence detector, qualitatively by retention time, and quantified by external standard method


    3.


    (1) Acetonitrile : pesticide residue level


    (2) N-hexane : pesticide residue level


    (3) Dichloromethane : pesticide residue level


    (4) Acetone : pesticide residue level


    (5) Sodium chloride : pure superior grade


    (6) Anhydrous sodium sulfate : pure top grade


    (7) Diatomaceous earth: solvent cleaning (cleaning solvent: a mixed solvent of n-hexane-dichloromethane equal volume), after cleaning, take it out and place it in a fume hood to dry and seal for later use


    (8) Quartz sand: 40-100 mesh, burn it in a muffle furnace at 450℃ for 4h before use


    (9) Silica gel (for column chromatography): chromatography grade, 70-230 mesh


    (10) Alumina: burn at 250°C for 4 hours → let cool in a fume hood → add 3% (mass ratio) ultrapure water to deactivate → fully shake (1 shake every half day, 30 min each time, 2 times in total) Once added with n-hexane, soak and preserve (equilibrium)


    (11) Extractant: Add a mixture of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 2:1 to ultrapure water, and adjust the pH to 3.


    (12) Polycyclic aromatic hydrocarbon mixed standard solution: ρ=200ug/mL, and the solvent is methanol


    Four, instruments and equipment

    (1) Solution delivery pump
    .

    (2) Flip the oscillator
    .

    (3) Pressure fluid extraction device
    .

    (4) High performance liquid chromatograph, with ultraviolet detector and diode array detector, chromatographic column: PAH special column (250mm×4.
    6mm×5um)
    .

    (5) Concentration device: equipment with equivalent performance such as nitrogen blowing concentrator and rotary evaporator
    .

    Five, pre-treatment

    (1) Solid waste overflows liquid

    1.
    Preparation of leaching solution

    "Semi-Volatile Organic Compound Analysis Technology-Preparation of Sulfuric Acid and Nitric Acid from Leachate"

    2.
    Extraction

    Measure 100 mL of the extract, add appropriate sodium chloride and 20 mL of dichloromethane to a 500 mL separatory funnel in turn , shake well, stand to separate the layers, remove water through a funnel containing an appropriate amount of anhydrous sodium sulfate, and collect the organic phase In a concentrating bottle, repeat the extraction twice as described above, combine the organic phases, wash the funnel and sodium sulfate layer 23 times with a small amount of dichloromethane, combine the organic phases in a 150mL pear-shaped bottle towel, and concentrate at least by rotary evaporation in a 35℃ water bath.
    Dissolve in n-hexane, continue to concentrate to about 1mL to be purified
    .
    If the sample does not need to be purified, concentrate the extract at least by adding about 3 mL of acetonitrile, continue to concentrate to at least 1 mL, transfer it to a cell flask, use acetonitrile to accurately make the volume to 1.
    0 mL, and wait for analysis on the machine
    .

    3.
    Purification

    Transfer the enriched sample solution (solvent is n-hexane, about 1 mL) to a silica gel-alumina chromatography column [where silica gel is 12 cm (the lower part of the column), and alumina is 6 cm (the upper part of the column).
    Add a small amount of anhydrous sodium sulfate at the top ], separate and purify, rinse with 10mL n-hexane , discard the eluent, elute with 80mL dichloromethane -n-hexane mixed solvent with a volume ratio of 3:7 , receive the eluent in In a 150mL pear-shaped flask, after concentrating to 35mL by rotary evaporation in a 35℃ water bath, add 3mL of acetonitrile, continue to concentrate to at least 1mL, transfer to a cell flask, accurately make the volume to 1.
    0mL with acetonitrile, and wait for analysis on the machine
    .

    (2) Solid waste

    1.
    Extraction (pressurized fluid extraction method)

    Take the solid waste sample, mix it with diatomaceous earth, make the sample fully dispersed, and fill it into the extraction tank.
    The extraction tank is filled with diatomaceous earth for compaction
    .
    The extraction conditions are as follows:

    Extraction solvent: a mixed solvent of equal volume of n-hexane and acetone
    .

    Extraction temperature: 100℃
    .

    Pressure: 1500psi
    .

    Static extraction time: 8min
    .

    Flushing volume: 60% of the volume of the extraction cell
    .

    Nitrogen purge: 60g, pressure 150psi
    .

    Number of static extraction cycles: 2
    .

    After the sample was dehydrated in an anhydrous sodium sulfate funnel, it was transferred to a 150 mL pear-shaped bottle, concentrated at least by rotary evaporation in a water bath at 35°C, and then dissolved in n-hexane , and then concentrated to about 1 mL to be purified
    .

    If the sample does not need to be purified, concentrate the extract at least by adding about 3 mL of acetonitrile, continue to concentrate to less than 1 mL, transfer it to a cell bottle, use acetonitrile to accurately make the volume to 1.
    0 mL, and wait for analysis on the machine
    .

    2.
    Purification

    The method is the same as the solid waste leachate
    .

    Related Links: Determination of 13 Semi-volatile Organic Compounds in Solid Waste Leachate-Gas Chromatography-Mass Spectrometry (2)

     

     

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