The national standard for soil microwave digestion method, the national standard stipulates whether

It is very important to choose different methods for different samples.

There are generally three ways to detect heavy metals such as soil and food.

1. Microwave digestion (microwave digestion instrument + acid repulsion instrument).

2. High-pressure digestion (high-pressure digestion tank + acid expulsion instrument).

3. Wet digestion (PTFE digestion tube + digestion instrument).

Teachers are welcome to add.

Fourth, the use of sound waves and then the elimination of that bacterium, said to have achieved the desired purpose, thus forming international law.

When performing microwave digestion of soil, we can operate such methods according to specific standards.

There are clear rules on the steps to be carried out, as well as the standards to be met for the operation.

This icon of the method of polluting Weibo dissipation is similar to this kind of icon, and I think it has a special meaning when it is marked.

Wu Chang microwave digestion method, the national standard soil microwave alkali elimination method is to appropriately add, subtract and offset the soil according to the fluctuation of the soil.

The microwave digestion method on the figure is overmarked, this should be checked on the Internet, or ask a professional.

The soil suddenly flew Weibo summary method international scolding words Weibo, but for the ** rate of that land after the end of the matter Fly is Fly Doctor so you can figure this out and know.

You want to comply with the national regulations and at the same time you have to use special equipment to handle it related to excel.

If you look at it according to the national standard, the general place will get the standard.

Soil microwave elimination method national standard In fact, there are professional group methods in the world, you can ask professional people.

Not necessarily need, the fixed volume is just for the convenience of calculation after the measurement, what components are you measuring in the soil, 50ml volumetric flask will dilute the components in the soil compared to 25ml, if the dilution of the composition concentration is too low to measure the front will be done in vain.

Of course, you can double the amount of soil sample, nitric acid and hydrofluoric acid to 50ml

However, the increase in the amount of soil sample will increase the difficulty of digestion, what method do you use to digest it?

The amount of acid is increased. Reduce the amount of acid added; Or after the digestion is completed, the electric hot plate will drive away the acid.

Microwave digestion was used instead of oil bath digestion or burning method to determine the content of organic matter in soil, and the relevant determination conditions of microwave digestion method were discussed in detail. Compared with the traditional potassium dichromate oil bath method, this method has the advantages of fast, economical and reproducible.

I just finished the soil digestion last week and the solution color is correct. If it is done in accordance with the national standard, the white precipitate may be salt, and hydrochloric acid or nitric acid can be added to continue digestion.

The black is organic matter, add perchloric acid to continue to digest, and then don't forget to drive the acid.

It is related to the type and composition of the ore contained in the soil at different levels, and the surface soil can generally be completely dissolved. Deeper soils are difficult to dissolve completely. If you only analyze the available state, you don't need to consider the dissolved sediment, you can refer to the EPA method for analyzing the soil, and the sediment is directly filtered out.

The pre-treatment of trace element determination in plants can be digested by microwave, the application of microwave digestion technology in biomedical and pharmaceutical analysis, the digestion of biological samples is the earliest field of microwave application, and the processing samples include animal, plant, food and medical samples, etc., Microwave digestion overcomes the shortcomings of the traditional dry or wet high temperature, loss of volatile elements, and time-consuming.

Microwave digestion usually refers to the use of microwave heating of the digestion solution (various acids, some lyes and salts) and samples in a closed container to quickly dissolve various samples under high temperature pressurization conditions (there are also open container microwave digestion, not discussed). The two characteristics of closed vessel reaction and microwave heating determine the advantages of complete, fast and low blank, but inevitably bring the disadvantages of high pressure (the hidden danger of possible overpressure) and small sample volume to digest. High pressure (up to 100-150 bar), high temperature (usually 180-240 bar), and strong acid vapors put psychological pressure on the experimenter in terms of safety.

The current commercial microwave digestion system generally has temperature and pressure measurement and even temperature and pressure control technology, so it has a greater guarantee in safety.

It depends on the amount of these two elements in your sample and what instrument you use to measure it. We use flame atomic absorption, and lead can be mixed up to 40 mg L, cadmium up to 5 mg L. If the content is low, you can mix it with a low point, and if the content is high, you can dilute it.

Or look for the method standards issued by my country!

The soil matrix is very complex and the lead content is very low, which is difficult to do with simple reagent analysis and must be combined with instrumental analysis.

The most internationally recognized method is: EPA3052 microwave digestion (measurable full amount) + ICP test.

The brief steps are as follows:

The sample was added to the reaction tube, an appropriate combination of three reagents of nitrate hydrochloride and hydrofluoric acid was added, the reaction tube was closed, the reaction was carried out under microwave conditions, the sample solution was filtered to a certain volume after the reaction was completed, and the content of various heavy metals was tested by ICP-OES (of course, AAS and ICP-MS can also be used).

EPA3052 is an authoritative standard of the United States Environmental Protection Agency, which talks about the sample preparation method of microwave digestion, mainly for soil, which is insoluble samples under conventional treatment. For ICP testing, EPA also has a related standard, EPA6010C. You can view these two standards online.

Oxidation to lead dioxide determination.