Acetonitrile as a commonly used organic chemical raw material
Acetonitrile (CH3CN) is a widely used organic chemical raw material. In addition to being used as an extractant for extracting butadiene and isoprene from olefins and paraffins in the petrochemical industry, it is also widely used. It is used as a synthetic raw material for organic synthesis, medicine, pesticides, surfactants, dyes and other fine chemicals, as well as a mobile phase solvent for thin layer chromatography, paper chromatography, spectroscopy, polarography and high performance liquid chromatography (HPLC). It has recently begun to be used. It is used as a DNA synthesis/purification solvent, a solvent for organic EL material synthesis, a cleaning solvent for electronic components, etc. These uses have high requirements for the purity of acetonitrile.
Application of acetonitrile in chromatography
Chromatographic acetonitrile refers to acetonitrile reagents used for chromatographic analysis, chromatographic separation, and chromatographic preparation
In high-performance liquid chromatography (HPLC) analysis, the purity and quality of the mobile phase solvent have an important impact on the analysis results and the instrument itself.
Various trace impurities in the solvent will not only cause higher baselines and ghost peaks, thereby affecting the qualitative and quantitative analysis results, but may also contaminate the separation column and clog the system, causing instrument failure. Understanding HPLC solvent specifications and related test methods can help HPLC users evaluate and screen HPLC solvents and reduce the negative impact of solvent impurities on applications.
Acetonitrile is the most commonly used organic mobile phase component
The unique properties of acetonitrile that distinguish it from other HPLC solvents (medium elution ability, strong solubility, ability to obtain clear chromatographic peaks, low viscosity, and lower UV absorption compared to alcohols and esters) make it a The most commonly used organic mobile phase components. Acetonitrile is generally a by-product of the large-scale production of acrylonitrile (from ammonia and propylene). It may contain a variety of very small impurities (such as acrylonitrile, α(β)-methacrylonitrile, cis/trans-butenenitrile, acetaldehyde, acetone, methanol, ethyl cyanide, acrolein, allyl alcohol, acrylic acid, oxazole and acetic acid).
After a complex purification process, trace amounts of the above impurities may still be present in HPLC grade acetonitrile. Some of these impurities will not only cause higher baselines and ghost peaks, thereby affecting qualitative and quantitative analysis, but will also contaminate the analytical column, block the system, and cause instrument failure.
Judgement of UV absorption value of acetonitrile by HPLC
UV absorption background is critical for HPLC acetonitrile for two reasons. First, most organic impurities produce UV absorption. The smaller the UV absorption of acetonitrile means there are fewer impurities in it. Second, the most commonly used detection mode of HPLC instruments is UV detection. Therefore, the smaller the UV absorption of acetonitrile, the lower the baseline background of the chromatogram; thus, the higher the sensitivity and the lower the detection limit.
Safety requirements for acetonitrile .
1. Acetonitrile is a highly dangerous product with flammable and explosive properties. The explosion limit of the mixture of steam and air is 4.4% to 16% (V/V). When exposed to open flames or high heat, it can cause combustion and explosion. Its vapor is heavier than air. It can spread to a considerable distance from a lower place and cause backfire when encountering a fire source. Therefore, all preventive measures should consider how to avoid the formation of combustion and explosion conditions.
2. Acetonitrile is highly toxic, volatile, and irritating to the skin and mucous membranes. Personnel exposed to acetonitrile should be provided with labor protection measures to protect their skin and respiratory organs. The analysis of acetonitrile should be conducted in a fume hood. The maximum allowable concentration of acetonitrile in the air in the work area does not exceed 2mg/m3.
3. Acetonitrile reacts strongly with sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, perchlorate, etc. Contact with the above substances should be avoided. In places where acetonitrile is present, it is prohibited to use mechanical equipment and tools that are prone to sparks.
4. Leaked acetonitrile can be absorbed by activated carbon or other inert materials, and then collected and transported to a waste disposal site for disposal. It can also be flushed with large amounts of water, and the flushing water can be put into the wastewater system for treatment.
5. Fire-fighting equipment should use foam, carbon dioxide fire extinguishers, or sand.
Acetonitrile handling precautions and storage
Operation precautions: Close tightly and provide adequate local exhaust and general ventilation. The operation should be as mechanized and automated as possible. Use explosion-proof ventilation systems and equipment. Keep away from flammable and combustible materials. Prevent vapors from leaking into the workplace air. Avoid contact with oxidants, reducing agents, acids, and alkalis. When handling, load and unload with care to prevent damage to packaging and containers. Equipped with corresponding varieties and quantities of fire-fighting equipment and leakage emergency treatment equipment. Empty containers may be harmful residues.
Storage precautions: Store in a cool, ventilated warehouse. Keep away from fire and heat sources. The storage temperature should not exceed 30℃. Keep container tightly sealed. They should be stored separately from oxidants, reducing agents, acids, alkalis, combustibles and edible chemicals, and avoid mixed storage. Use explosion-proof lighting and ventilation facilities. It is prohibited to use mechanical equipment and tools that are prone to sparks. The storage area should be equipped with emergency release equipment and suitable containment materials.
Use protection of acetonitrile
Provide safe showers and eyewash facilities whenever possible.
Respiratory system protection: When you may be exposed to poisons, you must wear a filtering gas mask (full face mask), self-contained breathing apparatus or ventilated respirator. Wear air respirators during emergency rescue or evacuation.
Eye protection: Protection has been included in respiratory protection.
Physical protection: Wear tape protective clothing.
Hand protection: Wear rubber and oil-resistant gloves.
Recycling of acetonitrile
Due to the low recovery rate, high cost, and limited use of acetonitrile in the 1960s and 1970s, many acrylonitrile manufacturers burned crude acetonitrile as fuel or disposed of it through deep well injection, and some even discharged it directly into the environment. This not only fails to make good use of resources, but also causes serious pollution to the environment. With the increasing development of science and technology, the uses of acetonitrile are becoming more and more extensive, and the recycling of acetonitrile is also receiving more and more attention.
In the past two decades, people have continuously improved the acetonitrile purification and refining processes. The quality of acetonitrile has been greatly improved, and the demand has continued to increase. Recycling acetonitrile and effectively utilizing acetonitrile is an important way to improve economic and social benefits. Therefore, for a long time, the preparation of high-purity acetonitrile suitable for different uses, or even one high-purity acetonitrile suitable for multiple uses, has been a hot research topic at home and abroad.
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