
(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
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.
2、 Testing process
Refer to the user manual
3、 Instrument technical specifications
1. Instrument transmittance accuracy ≥ ± 0.5%
2. Instrument repeatability ≤± 0.05%
3. Instrument stability without drift/30 minutes (after preheating the instrument for 5 minutes)
4. Linear error ≤ 0.2% (0.002, copper sulfate detection)
5. Instrument power consumption ≤ 5W
6. Power supply AC220V/50Hz or DC12V
7. The built-in thermal printer can automatically print out the detection results, which is convenient and intuitive.
4、 Instrument measurement items
1. Instrument measurement items
Determination of heavy metals (lead, arsenic, chromium, cadmium, mercury, iron, zinc, manganese, copper) in soil, fertilizers, food, plants, vegetables, and fruits.
2. Instrument expansion testing project
The instrument can be extended to measure the content of major and trace elements in soil and fertilizers.
5、 Instrument testing characteristics
1. This is an upgraded version of the HED-ZSD soil heavy metal detector, with a spray coated steel plate shell design that is sturdy and durable, and comes with a complete set of accessories and finished chemicals.
2. The performance is reliable, and the working stability is 5-6 times better than the national standard JJG79-90. The unique design of the anti-interference optoelectronic module has better repeatability than the indicators of grating spectrophotometers. It adopts microprocessor technology, high-performance chip intelligent program control, touch buttons, and easy operation.
3. 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.
4. Strong scalability, this instrument can not only be used for heavy metal detection but also for testing nutrients in soil, fertilizers, and plants, making it versatile.
5. 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.
6、 Configuration List (Two Aluminum Alloy Boxes):
Instrument box |
Medicine box |
||||
Serial Number |
Name |
quantity |
Serial Number |
Name |
quantity |
01 |
Host (built-in printer) |
1 unit |
01 |
Medication for soil nutrient determination |
1 set |
02 |
pH electrode |
1 piece |
02 |
Triangle bottle 100ml |
2 pieces |
03 |
Colorimetric dish |
4 pieces |
03 |
volumetric flask |
1 piece |
04 |
Electronic balance (100g/0.01g) |
1 unit |
04 |
Bottle washing |
1 piece |
05 |
fuse |
2 of them |
05 |
Jiao spoon |
1 set |
06 |
Host power cord |
1 piece |
06 |
Qualitative Filter |
2 boxes |
07 |
DC 12V line |
1 piece |
07 |
suction bulb |
1 piece |
08 |
Scale straws 1, 5, 10ml |
1 each |
08 |
Small aluminum box |
1 piece |
09 |
Straw (3mL) |
12 pieces |
09 |
Measuring cylinder (50mL) |
1 piece |
10 |
Instruction manual, certificate of conformity |
1 set |
10 |
10ml centrifuge tube |
40 of them |
11 |
|
|
11 |
Centrifugal tube rack |
1 piece |
12 |
|
|
12 |
Glass reaction tube |
10 of them |
Article address: https://www.turangsuceyi.com/trzjs/7.html Shandong Horde Electronic Technology Co., Ltd. produces and wholesales soil nutrient detectors, soil fertilizer rapid testers, soil measuring instruments, and soil fertilizer nutrient rapid testers. The manufacturer provides free prices for soil nutrient rapid testers and shares knowledge about the use and application of fertilizer rapid testers; If you need to reprint, please indicate the source of this article!