Soil heavy metal detection equipmentSoil heavy metal detection equipmentThe main heavy metal pollutants in soil include mercury, cadmium, lead, copper, chromium, arsenic, nickel, iron, manganese, zinc, etc. Although arsenic is not a heavy metal, its behavior, sources, and hazards are similar to those of heavy metals, so it is usually classified as a heavy metal for discussion.In terms of the needs of plants, metal elements can be divided into two categories: ① Elements that are not needed for plant growth and development, but pose significant health hazards to humans, such as cadmium, mercury, lead, etc. ② The elements required for normal plant growth and development, as well as certain physiological functions for the human body, such as copper, zinc, etc., but excessive amounts can cause pollution and hinder plant growth and development.
Instrument testing characteristics
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.

Soil heavy metal detection equipmentDetection principle:
（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 the safety and quality of agricultural products and the allowable limit for 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
Using the national standard (GB/T50091.1-2003) borohydride/compound reduction colorimetric method, the sample is digested and then potassium iodide thiourea is added and heated to reduce pentavalent arsenic to trivalent arsenic. Under acidic conditions, borohydride/potassium hydride reduces trivalent arsenic to negative trivalent, forming arsine that is introduced into the absorption solution and appears yellow. The arsenic content is determined by instrument detection.