With the development of modern industry, more and more pollutants are being discharged from the industry, especially the soil heavy metal pollution caused by it is becoming more and more serious, which poses a huge threat to human life. In the current process of agricultural development, utilizingHeavy metal detectorCarrying out soil heavy metal detection has become a very important content. Based on this situation, we have developed a rapid determination method for heavy metals, which can quickly and jointly determine lead, arsenic, chromium, cadmium, mercury, etc. in samples such as vegetables, food, soil, organic fertilizers, tobacco leaves, etc.

1Detection principle of soil heavy metal detector：

（1） After digestion of the sample, all forms of heavy metals (including arsenic, lead, cadmium, chromium, mercury, nickel, iron, aluminum, zinc, manganese, copper, etc.) are converted into ionic forms. After adding relevant detection reagents, the color develops. Within a certain concentration range, the depth of the solution color is proportional to the content of heavy metals, following the Lambert Beer law. The content value is then measured by instruments and compared with the national standard for agricultural product safety quality and pollution-free vegetable safety requirements to determine the content of heavy metals in vegetable samples.

（2） Detection principles and standards for various heavy metals

1. The detection principle and adopted standards of heavy metal arsenic

Adopting the national standard (GB/T50091.1-2003) borohydride reduction colorimetric method, the sample is digested, potassium iodide thiourea is added and heated to reduce pentavalent arsenic to trivalent arsenic. Under acidic conditions, potassium borohydride reduces trivalent arsenic to negative trivalent, forming arsine, which is introduced into the absorption solution and appears yellow. The arsenic content is detected by the instrument.

2. The detection principle and adopted standards of heavy metal lead

The national standard (GB/T5009.12-2003) dithizone colorimetric method is adopted, which means that after digestion of the sample, under weakly alkaline conditions, lead ions form a red complex with dithizone, dissolve in it, and perform colorimetric determination.

3. The detection principle and adopted standards of heavy metal chromium

After digestion of the sample, in the presence of divalent manganese, chromium ions react with diphenylcarbazide to form a purple red complex. The color of the complex is directly proportional to the hexavalent chromium content, and the chromium content can be determined by colorimetric analysis.

4. The detection principle and adopted standards of heavy metal cadmium

Using the national standard (GB/T5009.15-2003) colorimetric method, after digestion of the sample, under alkaline conditions, cadmium ions form a red complex with 6-bromobenzothiazole azo naphthol, dissolve in it, and then perform colorimetric determination.

5. The detection principle and adopted standards of heavy metal mercury

The national standard (GB/T5009.17-2003) dithizone colorimetric method is adopted, which means that after digestion of the sample, under acidic conditions, mercury ions form an orange red complex with dithizone, dissolve in it, and perform colorimetric determination.

IIAdvantages of Soil Heavy Metal Detector

1. The performance is reliable, and the working stability is 5-6 times better than the national standard JJG79-90. The repeatability reaches the index of grating spectrophotometers. It adopts microprocessor technology, microcontroller control, touch buttons, and is easy to operate.

2. The heavy metal testing adopts joint digestion and sub item testing techniques, simplifying the testing process, reducing testing time, greatly improving testing efficiency, and enhancing testing accuracy.

3. Strong scalability, this instrument can not only detect heavy metals but also expand the testing of nutrients in soil, fertilizers, and plants, making it versatile.

4. The soil heavy metal detector integrates medicine, equipment, and instruments into one, equivalent to a small laboratory with two aluminum alloy boxes, easy to carry, convenient for on-site testing, and mobile service. Suitable for grassroots testing departments to screen vegetables, fruits, and other foods containing heavy metal pollution.

Heavy metal detectorThe application of this technology provides a high-precision, low-cost, and time-saving solution for soil heavy metal detection, which is more conducive to enterprises or relevant departments working together to control costs. It not only meets the requirements of scientific analysis experiments, but also helps to quickly pre screen samples, optimize the laboratory analysis process, and reduce the workload of analysis. Therefore, it can be said that this is a very practical soil detection instrument.