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What is the detection principle of the heavy metal detector?

Author:QINSUN Released in:2023-05 Click:124

The heavy metal detector is mainly composed of a metal detector and an automatic removal device, of which the detector is the core part.

There are three sets of coils distributed inside the detector, namely the central transmitting coil and two equal receiving coils;

To through the central transmitter coil A The connected oscillator is used to generate a high frequency variable magnetic field. At rest, the induced voltages of the receiver coils on both sides cancel each other out and reach a balanced state before the magnetic field is disturbed.

Once the metal impurities enter the magnetic field area and the magnetic field is disturbed, this balance will be broken and the induced voltage of the two receiver coils cannot be compensated;

The induced voltage that has not been canceled is amplified and processed by the control system, and a signalal alarm is generated (metallic impurities are detected).

The system can use the alarm signal to drive the automatic reject device, etc., to exclude metal impurities from the production line.

Heavy Metal Detector Detection Principle:

After the sample is digested, all forms of heavy metals are converted into ionic forms, and the corresponding detection of reagents are added In a certain concentration range, the color of the solution is proportional to the heavy metal content;

Then the content value is obtained by measuring instrument, which is in line with the national standard for the safety and quality of agricultural products and the safety of unpolluted vegetables. It is necessary to compare the standards of allowable limits for judging the content of heavy metals in vegetable samples.

The detection process of the dheavy metal detector is as follows:

1. First rinse the sample to be tested with distilled water or pure water (wash the surface soil, so as to not to interfere with the detection), dry, cut the sample into small pieces of about 1cm with a knife or scissors, weigh 1g of the treated sample and place it in a 20mL plastic collection tube, add 10mL of water.

2. Add 4 drops of reagent A, squeeze the sample under the surface of the liquid with a stirring needle, cover the cap of the sampling tube, shake it high down 10 times, let it stand for 1min, then shake it up and down 10 times, the fruit and vegetable samples were taken, and the solution was used as a test solution for further use.

3. Pipette 1 mL of the sample solution into a blank sample tube.

Add 3 drops of reagent B, cover the bubblechon of the collection tube, swirl 5 times, then add 2 drops of reagent C and 2 drops of reagent D, swirl up and down 5 times, develop color at room temperature for 5 minutes.

By comparing the sample tube with the rapid test card for the lead content of fruits and vegetables, the reference concentration of the lead content in the tested sample can be read .


When the sample contains iron ions, calcium ions, magnesium ions and other metal ions, this can result in false positives for solution color development. This method is suitable for the determination of free lead, and the determination of organic lead should be digested according to conventional laboratory methods.

Label: heavy metal detector