1、 Overview of high-precision soil heavy metal detector:

The problem of heavy metal pollution in soil is becoming increasingly serious, causing a large accumulation of heavy metals such as cadmium, copper, arsenic, chromium, mercury, iron, zinc, manganese, copper, nickel, aluminum, fluorine, titanium, selenium, etc. in the soil tillage layer, which has become one of the main environmental problems currently faced. Heavy metals in soil accumulate in crops and enter the food chain, posing a serious threat to human and animal health. The mining of non-ferrous metal mines, the discharge of industrial "three wastes", the accumulation of heavy metal containing waste, sewage irrigation in agricultural production, and the unreasonable use of agricultural chemicals may all lead to the direct or indirect entry of harmful heavy metal elements into the soil, resulting in serious exceedance of heavy metal content in soil, crops, fruits and vegetables, water quality, aquatic products, etc. However, the current heavy metal determination methods have slow determination speed, cumbersome steps, and expensive instruments. Based on this situation, we have developed a rapid determination method for heavy metals.

2、 Testing items:

Rapid combined determination of arsenic, lead, cadmium, chromium, mercury, nickel, aluminum, fluoride, titanium, selenium, iron, aluminum, zinc, manganese, copper, etc. in soil, fertilizers, crops, vegetables, fruits, water quality, food and other samples.

3、 Detection speed:

Lead, arsenic, chromium, cadmium, mercury, and five other tests take about 60 minutes (including soil sample pretreatment and reagent preparation)

Single item detection of iron, zinc, manganese, copper, and aluminum takes about 30 minutes (including soil sample pretreatment and reagent preparation)

4、 Detection principle of soil heavy metal detector:

（1） After digestion of the sample, all forms of heavy metals (including arsenic, lead, cadmium, chromium, mercury, nickel, aluminum, fluorine, titanium, selenium, iron, zinc, manganese, copper, etc.) are converted into ionic forms. After adding relevant detection reagents, the color appears. 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 determined 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

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 chloroform, 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 react with 6-bromophenylthiazolylazo naphthol to form a red complex, which is dissolved in chloroform for 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 chloroform, and perform colorimetric determination.

5、 Functional features:

1. This instrument integrates various functions into one, without the need for users to provide their own accessories, and can flexibly flow for detection.

2. Android operating system, the main control chip adopts ARM Cortex-A7, RK3288/4-core processor, with a main frequency of 1.88GHz, faster running speed and stronger stability.

3. 6 detection channels (solid-state design), can quickly detect 6 samples at once, greatly improving detection efficiency and reducing detection costs.

4. Built in calibration function during the detection process, intelligent constant current voltage stabilization, and automatic calibration of light intensity ensure detection accuracy.

5. The built-in crop expert fertilization system can calculate recommended fertilization amounts for over a hundred national agricultural economic crops, fruit trees, and other target yields, and scientifically guide agricultural production based on fertilization formulas. The results of soil testing formula fertilization can be printed, including: crop type, fertilizer type, target yield, total demand, and recommended fertilization plan.

6. The instrument comes standard with WiFi wireless upload, 4G network transmission, and GPRS wireless remote transmission function, allowing for quick data upload.

7. The instrument has a built-in large capacity memory, which supports viewing all historical detection records and transmitting all detection data.

8. Equipped with a smart cloud agriculture platform, the instrument can be connected to a wireless network to selectively or batch upload detection data wirelessly, making it convenient for users to conduct long-term data management and visual analysis.

9. The instrument has both USB and Ethernet interfaces, and can copy data from a USB drive at any time.

10. You can log in to the cloud platform at any time with your mobile phone and view historical data online

11. Built in plant nutrition diagnostic standard map, based on images of nutrient deficiency in various crops, conduct leaf comparison to diagnose abundance and deficiency.

12. 4 wavelength professional testing cold light source (red, blue, green, orange), the light source wavelength is stable, the light source works continuously for a long time without temperature drift, the lifespan is up to 100000 hours, the reproducibility is good, and the accuracy is high.

13. The colorimetric cell adopts a standard 1cm colorimetric dish, with no mechanical displacement or wear. The optical path testing positioning is precise, effectively shielding external light interference and ensuring that the detection results are better than the national standard requirements.

14. The instrument system comes with sample pre-treatment operation videos, and various sample detection methods can be viewed by clicking on the video module. Testing personnel do not need to self-study the manual, and the guidance and teaching are convenient and fast, making it easy for beginners to operate quickly.

15. Built in new generation high-speed thermal printer (no ribbon required), printing content includes information such as testing unit, testing personnel, testing items, channel number, absorbance, nutrient content (mg/kg), testing time, and QR code

16. High sensitivity 7-inch true color touch screen, adopting more efficient and user-friendly operation, high-definition and high interactive display, greatly reducing the tedious operation and errors of traditional instruments.

17. Built in clock function, convenient for time recording and long-term historical traceability.

18. Multiple account passwords can be set for login, with an efficient UI interactive interface. Different users can freely add and edit detection information, which can be saved for long-term use.

19. GPS function: It can record latitude and longitude locations during field operations to meet special user needs.

20. Built in low voltage prompt function, which can clearly indicate the battery level during detection to avoid test data deviation. At the same time, it has power-off protection function, which automatically saves data during power-off to prevent data loss.

21. Dual use AC/DC power supply method, built-in large capacity rechargeable lithium battery, can work continuously for more than 10 hours when fully charged, and can also be connected to an external vehicle power supply for storage.

22. The instrument has a Chinese English switching function, which can meet export requirements.

23. High strength PVC engineering plastic carrying case design, sturdy and durable, easy to carry.

6、 Technical parameters:

1. Power supply: AC 220 ± 22V DC 12V+5V (the instrument has a built-in lithium battery and can also be powered by a car power supply)

2. Power: ≤ 5W

3. Range and Resolution: 0.001-9999

4. Repeatability error: ≤ 0.03% (0.0003, potassium dichromate solution)

5. Instrument stability: No drift in displayed numbers within one hour (transparency measurement); The numerical drift within two hours should not exceed 0.3% (0.003 for transparency measurement) and 0.001 (for absorbance measurement).

6. Linear error: ≤ 0.1% (0.001, copper sulfate detection)

7. Sensitivity: Red light ≥ 4.5 × 10-5 Blue light ≥ 3.17 × 10-3 Green light ≥ 2.35 × 10-3 Orange light ≥ 2.13 × 10-3

8. Wavelength range: Red light: 680 ± 2nm; Blue light: 420 ± 2nm; Green light: 510 ± 2nm; Orange light: 590 ± 4nm

12. Display screen resolution: 1024 * 600

13. Seismic rating: IP65

14. Instrument size: 48 × 34.5 × 22cm

15. Net weight of the host: 5.2kg