Determination of heavy metal ion content in water samples

You can check the emission standards first, and then there are metal ion detection methods, and then you are looking up the specific steps.

Summary. Atomic spectroscopy is an important method for trace element analysis, which includes atomic absorption spectrometry, atomic emission spectrometry and atomic fluorescence spectroscopy. It has the advantage of low detection limit and high sensitivity.

Atomic absorption spectrometry is characterized by high detection sensitivity, fast analysis speed, low interference when determining high concentration of elements, and stable signal. The disadvantage of atomic absorption spectrometry is that the light source of the element is needed for the determination of a certain element, and it is still difficult to measure multiple elements at the same time, and the interference of the determination of complex samples is more serious, and the determination sensitivity of some elements is not enough.

Atomic spectroscopy is an important method for trace element analysis, which includes atomic absorption spectrometry, atomic emission spectrometry and atomic fluorescence spectroscopy. It has the advantage of low detection limit and high sensitivity. Atomic absorption spectrometry is characterized by high detection sensitivity, fast hail swimming, low interference and stable signal when determining high concentration elements.

The disadvantage of atomic absorption spectrometry is that the light source of the element is required for the determination of a certain element, and it is still difficult to measure multiple elements at the same time, and the interference for the determination of complex samples is more serious, and the determination spirit or sensitivity of some elements is not enough.

Spectrophotometry is a method of qualitative and quantitative analysis of a substance by determining the absorption of light at a fixed wavelength or within a certain wavelength range, and the basic principle of quantitative detection by UV-Vis spectrophotometry is Beer-Lambert's law (a= bc). UV-Vis spectrophotometry has the advantage of being simple to use and is a relatively inexpensive method of detection, as most ions in water samples can be determined by UV-Vis spectrophotometry with very low detection limits. Of course, visible spectrophotometry also has drawbacks:

The spectral interference is serious and the selectivity is insufficient; Analytical substances usually have to be transformed into light-absorbing substances with a chromogenic agent, and some metal ion chromogenic agents are not easy to obtain, difficult to select, and sometimes bring the interference of collaterals. Some scholars have studied the chromogenic reaction of lead with 2-(3,5-dipyridine azo)-5-diethylaminophen (3,5-dicl-padap), and established a new method for spectrophotometric determination of trace amounts of lead in cosmetics.

Mass spectrometry is to transform the molecules of the substance to be measured into charged particles, and use a stable magnetic field (or alternating electric field) to separate the charged particles according to the size of the nucleus-to-mass ratio, and form a spectrum that can be detected. In the detection of heavy metals, plasma mass spectrometry (ICP-MS) is generally used, in which the inductive lotus plasma is combined with mass spectrometry, and the inductive lotus plasma is used to vaporize the sample, and the nucleus of the metal to be tested is separated blindly, so as to be changed to human mass spectrometry for determination.

There are many rapid test methods.

Method 1: Use a portable instrument for detection.

Method 2: Rapid detection of heavy metals in water using dipstick method.

Method 3: The possibility of detecting the degree of heavy metal pollution. Different concentrations of heavy metals such as zinc, copper, and lead were added to the CA medium, and then the water mold strains were moved to these media for culture. According to the experimental results, when the medium contains 500 ppm zinc sulfate, 40 ppm copper sulfate and 500 ppm lead nitrate, the water mold cannot grow. However, when containing 450 ppm zinc sulfate, 30 ppm copper sulfate and 450 ppm lead nitrate, water mold can still grow and reproduce although it does not grow well.

Because the water mold grows very quickly in the environment of appropriate humidity, temperature and the right amount of light, about 1 2 days, so it can be very quickly tested for the content of heavy metals in the water, and the strain is easy to obtain, and the culture material is very cheap, therefore, the use of water mold or the detection of water mold content in the water can be used as one of the very economical, fast, simple and accurate reference indicators for detecting the degree of heavy metal pollution. As for the sensitivity of water mold to various heavy metals and how to promote the application of water mold to detect heavy metal pollution in water and even soil, further tests and improvements need to be made.

The original meaning of heavy metals refers to metals with a specific gravity greater than 5, including gold, silver, copper, iron, lead, etc., and heavy metals accumulate in the human body to a certain extent, which will cause chronic poisoning.

Heavy metal elemental substances are insoluble in water, not absolutely insoluble in water, but soluble in water in trace amounts.

Heavy metal ions are soluble in water, such as agno3, and the content of heavy metals in water is determined to include ions.

The so-called insoluble in water is not absolutely insoluble in water, but very small amounts soluble in water. In fact, there is no such thing as absolutely insoluble in water.

In fact, there are absolutely insoluble substances, and some of them will be dissolved.

Use the digestion method! You go to check the national standards network, there is a description of the measurement method! If you need me here, leave an email!

The original meaning of heavy metals refers to metals with a specific gravity greater than 5, including gold, silver, copper, iron, lead, etc., and heavy metals accumulate in the human body to a certain extent, which will cause chronic poisoning.

Heavy metals are insoluble in water, not absolutely insoluble in water, but dissolved in water in trace amounts.

Heavy metal Schiphorn ions are soluble in water, such as AGNO3, and the content of heavy metals in water is also determined to include ions.

I'll give you a rough idea, because I haven't measured these metals spectrophotometrically. But I have been exposed to the chemical analysis aspect before:

1. After the mercury is digested in the water sample, hydroxylamine hydrochloride is added to reduce the excess oxidant, and then the dithione hydrazone solution is added, at this time, the mercury and dithione hydrazone will react to form an orange chelate, and then extracted with carbon tetrachloride, and the absorbance is determined at a wavelength of 485nm.

2. After cadmium is also digested, dithionehydrazone solution is added, and a red chelate is formed at this time, which is extracted with chloroform and colorimetric absorbance is determined at 518nm. Add a little potassium sodium tartrate as a masking agent.

3. After the selenium water sample is digested, 2,3-diaminobenzidine solution is added as a chromogenic agent.

4. Silver and silver are difficult to measure, and the chromogenic agent is 3,5-br2-padap solution.

For the time being, I only remember this, because I usually use atomic absorption or atomic fluorescence measurement, so I can't remember spectrophotometry clearly. Hope it helps.

1. Two types of crops were selected: one was the crops produced by the farmland irrigated with the S river water, and the other was the crops produced by the farmland irrigated with non-polluted river water for comparison; The heavy metal content of the two types of crops was detected separately, and the heavy metal content of the two crops was compared (because the heavy metal will not be digested by plants, so the best way to detect the heavy metal content is to detect the heavy metal content);

2. At least two river water samples were selected: one was the polluted water sample downstream of the coal washing plant, and the other was the unpolluted water sample upstream of the coal washing plant, and the SS and heavy gold content content of the two were tested separately.

3. Ask experts or quote ** to cite the harm of heavy metals to the human body (heavy metals are difficult to be digested by animals and plants, and will be deposited in the food chain, and there are related cases of heavy metal poisoning abroad).