First, aluminum
Aluminum is a macro element in nature, and its toxicity is not great. However, excessive intake of human body can interfere with the metabolism of phosphorus and inhibit the activity of pepsin. For the content of aluminum in clean water, the World Health Organization ( WHO ) has a control value of 0.2 mg/L ; the limit in China's "Code for Hygienic Application of Water Quality" is also the value.
The measurement methods of aluminum include inductively coupled plasma atomic emission spectrometry ( ICP-AES ), indirect flame atomic absorption spectrometry, and spectrophotometry. The spectrophotometric method is interfered by the coexisting component iron and alkali metal and alkaline earth metal elements.
Second, mercury
Mercury and its compounds are highly toxic substances. The mercury content in natural water generally does not exceed 0.1 μg/L ; the median limit of China's “Sanitary Standard for Drinking Water Quality†is 0.001 mg/L .
Mercury is determined by dithizone spectrophotometry, cold atomic absorption spectrometry, cold atomic fluorescence spectrometry and atomic fluorescence spectrometry. Dithizone spectrophotometry is a standard method for the determination of various metal elements, but the measurement requirements are strict and the operation is cumbersome. The other three methods are special methods for the determination of trace and trace mercury in water. The determination is simple, the interference factors are small, and the sensitivity is low. Higher.
Third, cadmium
Cadmium is a highly toxic metal that can accumulate in the liver, kidney and other tissues of the human body, causing damage to organs and tissues, especially for kidney damage; it can also cause osteoporosis and induce cancer. The limit of cadmium in China's "Hygienic Standard for Drinking Water Quality" is 0.005mg/L .
The main methods for determining cadmium are atomic absorption spectrometry, dithizone spectrophotometry, anodic stripping voltammetry and inductively coupled plasma atomic emission spectrometry ( ICP-AES ).
Fourth, lead
Lead is a toxic metal that can accumulate in humans, animals, and plants. Its main toxic effects are anemia, neurological dysfunction, and kidney damage.
The method for determining lead in water is the same as the method for determining cadmium. Atomic absorption spectrometry and dithizone spectrophotometry are widely used. Anodic stripping voltammetry, oscillopolarography and inductively coupled plasma atomic emission spectrometry can also be used. ( ICP-AES ) method.
Five, copper
Copper is an essential trace element in the human body. The lack of copper can cause anemia, diarrhea and other diseases, but excessive intake of copper can also cause harm. Copper is more harmful to aquatic organisms, and its toxicity is related to morphology.
Method Determination of copper in water mainly atomic absorption spectrometry, sodium diethyl dithiocarbamate spectrophotometry and 2, 9-dimethyl-1, 10-phenanthroline spectrophotometry may also be used anodic stripping voltammetry , oscillopolarographic analysis, ICP-AES , etc.
Six, zinc
Zinc is also an indispensable element of the human body. A few milligrams of zinc per liter of water is harmless to humans and warm-blooded animals, but has a greater impact on fish and other aquatic organisms. Zinc has a certain inhibitory effect on the self-purification process of water.
Atomic absorption spectrometry for the determination of zinc, high sensitivity, less interference, suitable for a variety of water bodies. In addition, dithizone spectrophotometry, anodic stripping voltammetry or oscillopolarographic analysis, ICP-AES can also be used. For the waste water with high zinc content, in order to avoid the error introduced by high dilution, dithizone spectrophotometry can be used; for the determination of trace salt with high salt content and trace zinc in seawater, anodic stripping voltammetry can be used. Method or oscillographic polarography.
Seven, chromium
The common valence states of chromium are trivalent and hexavalent. In water, hexavalent chromium generally exists in the form of three kinds of anions such as CrO 4 2- , HCr 2 O 7- and Cr 2 O 7 2- ; it is affected by factors such as pH , temperature, redox species, organic matter, etc. Chromium and hexavalent chromium compounds can be converted into each other.
Chromium is one of the trace elements necessary for living organisms. The toxicity of chromium is related to its valence state. Hexavalent chromium is highly toxic, carcinogenic, and easily absorbed by the body and accumulated in the body. Hexavalent chromium is generally considered to be 100 times more toxic than trivalent chromium, but trivalent chromium compounds are more toxic to hexavalent chromium for fish. When 1mg/L , the water is yellow and has astringency; when the concentration of trivalent chromium reaches 1mg/L , the turbidity of water increases significantly.
The determination methods of chromium in water are mainly diphenylcarbazide spectrophotometry, flame atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry and ferrous sulfate titration. Spectrophotometry is a standard method commonly used in China and other countries. The titration method is applicable to water samples with high chromium content.
Eight, arsenic
Elemental arsenic is extremely low in toxicity, while arsenic compounds are highly toxic. Trivalent arsenic compounds are more toxic than other arsenic compounds. Oral administration of 0.1 g of arsenic trioxide (commonly known as arsenic) can cause death. Arsenic compounds are easily accumulated in the human body, causing acute or chronic poisoning.
The method for determining arsenic in water is a new silver salt spectrophotometry, silver diethyldithiocarbamate spectrophotometry, hydride generation - atomic absorption spectrometry, atomic fluorescence spectrometry, and ICP-AES .
Edited by Yingnuo Instruments
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