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    Home > Chemicals Industry > Chemical Technology > Rapid detection of organophosphorus and carbamate pesticide residues (instrument method)

    Rapid detection of organophosphorus and carbamate pesticide residues (instrument method)

    • Last Update: 2022-03-17
    • Source: Internet
    • Author: User
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    In agricultural production, chemical pesticides will be used for a long period of time.


    After food poisoning occurs, rapid screening to find out whether it is caused by organophosphorus or carbamate pesticides or rodent poison is of great significance for timely rescue of the injured


    In the past cases of pesticide poisoning, more than 95% are caused by organophosphorus or carbamates, so it is the focus of pesticide testing


    [Detection principle]

    This experiment uses the enzyme inhibition method for detection.


    This method uses enzyme-catalyzed hydrolysis of acetylcholine under certain conditions, and the hydrolyzate reacts with the color reagent to produce a yellow substance, which is absorbed at 412nm.


    This standard specifies a rapid test method for the determination of organophosphorus and carbamate pesticide residues in vegetables by the enzyme inhibition method


    [instrument]

    CL-BⅢ Four-channel Residual Pesticide Analyzer (Shanghai Fubo)


    [Steps]

    (1) Reagent preparation

    Extraction solution: buffer solution with pH 8.


    Enzyme reagent: acetylcholinesterase;

    Chromogenic agent: dithiodinitrobenzoic acid;

    Substrate: thioacetylcholine


    (2) Instrument settings

    ① Power-on settings


    ② Adjust 0/100:

    Press the "" (start control analysis) key, and wait for 3~5s;

    Press the "100" key to adjust "100" successfully;

    Put in the black block and wait for 3 ~ 5s;

    Press the "0" key to adjust "0" successfully;

    Press the "" (end analysis) key;

    Take out the black block


    Note: Each channel must do this once


    ③Blank control

    Use a large pipette to draw 2.


    Use a small pipette to take 0.


    Use a small pipette to take 0.


    Use a small pipette to take 0.


    Quickly shake the mixed liquid in the test tube and pour it into a cuvette;

    Put it into the colorimetric cell;

    Press the "Start Comparative Analysis" button;

    Wait for the end of the comparison
    .

    Note: The order of addition of extraction solution, enzyme reagent, color reagent, and substrate must be correct!

    ④Load control-local control library (test common vegetables)

    Press the "Load Control Analysis" button;

    Select the required control;

    Select the channel number that needs to be loaded into the control (tick √ before the channel number);

    Press the "read" button to complete the loading work;

    ⑤Sample detection

    Weigh 1g fruits and vegetables with a balance;

    Cut into 1cm square;

    Put it into the beaker, use a large pipette to draw 5mL of the extract and add it to the beaker;

    Let stand for 15 min (or shake for 1 min);

    Use a large pipette to extract 2.
    5 mL of soaking liquid from the beaker and transfer it to an empty test tube;

    Use a small pipette to take 0.
    1 mL of enzyme reagent and add it to the test tube;

    Use a small pipette to take 0.
    1 mL of the color developer and add it to the test tube;

    Let stand for 15 minutes;

    Use a small pipette to take 0.
    1 mL of the substrate and add it to the test tube;

    Shake well quickly and pour it into a cuvette;

    Put it into the colorimetric cell;

    Press the "Start Sample Analysis" button;

    Wait for the test result
    .

    ⑥Save test results

    After the sample is finished, the system automatically pops up the "Test Results" dialog box;

    Select the name of the vegetable to be measured in the channel;

    Fill in (select) the inspected unit and the production unit;

    Fill in (select) the testing unit;

    Press the "Save" button to save the test results
    .

    [Precautions]

    (1) Onion, garlic, radish, leeks, celery, coriander, water chestnut, mushroom and tomato juice contain plant secondary substances that have an effect on enzymes and are prone to false positives
    .
    When processing this kind of samples, whole plant (body) vegetable extraction can be used
    .
    For some vegetables containing more chlorophyll, the method of extracting whole plant (body) vegetables can also be used to reduce the interference of pigments
    .
    The sample processing methods for rice, millet, oatmeal, raisins, and soybeans are slightly different
    .

    (2) The test water needs to be distilled water or deionized water
    .
    All glassware and plasticware used in the test can be used repeatedly, but they must be soaked in detergent before use, rinsed with tap water 5 times, and then rinsed with distilled water 2 times, and used after drying
    .

    (3) Before the cuvette is put into the cuvette tank, the surface of the cuvette must be cleaned with the cuvette cleaning cloth or soft paper provided, and the bubbles in the solution must be removed
    .

    (4) Vegetables should not be cut too small, generally 1cm square is better
    .

    (5) For vegetables with dark colors, try to take half of the stem and half of the leaf
    .

    (6) For flavored vegetables, the control standard library of the detection software can be used to detect
    .

    (7) The tips of pipettes should not be contaminated with each other
    .

    (8) When adding reagents to the test solution with a pipette, make sure that the tip of the pipette is perpendicular to the liquid surface, and do not add reagents to the test tube wall
    .

    Related Links: Research Status of Rapid Testing Technology for Edible Fruits and Vegetables

     

     

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