The principle of nitrogen blowing instrument: blow nitrogen gas quickly, continuously and controllably to the surface of the heated sample, so that the water in the sample to be processed is quickly evaporated and separated, and the sample is concentrated anaerobicly.
Application: pesticide residue analysis, drug screening, liquid phase, gas phase, mass spectrometry analysis pretreatment.
advantage:
Disadvantages of fast drying speed:
High sample temperature and low sample processing volume There is a risk of blowing the material in the sample into the laboratory. It must be operated in a fume hood. Nitrogen consumption is required, which increases the additional cost. Flammable solvents pose a risk of explosion.
Rotary evaporator principle: The basic principle is vacuum distillation, which can reduce the boiling point of liquids. Those substances that will be thermally decomposed, oxidized or polymerized before reaching the boiling point during atmospheric distillation can be distilled out before decomposition. "Rotation" can Make the solvent form a thin film and increase the evaporation area. In addition, under the action of a high-efficiency cooler (generally a condenser), hot steam can be quickly liquefied to speed up the evaporation rate.
Application: Concentration of extract, extraction of organic matter, distillation of receiver liquid by chromatographic separation.
advantage:
The evaporation rate is relatively fast, the sample volume is large, the temperature of the water bath can be controlled, the heat input can be controlled, the degree of vacuum can be controlled, the whole process is visible, and the disadvantages of good control are:
Only a single sample can be processed. The glass device needs to be cleaned. The seal has a limited life span and needs to be replaced regularly. The sample will leak into the air, causing pollution
The principle of the centrifugal concentrator: negative pressure reduces the boiling point of the solvent, the cold trap captures the evaporated gas, and the evaporation process is carried out quickly. The centrifugal force can ensure that the sample is deposited on the bottom of the tube without product bubbles and cross-contamination.
Applications: Concentration of DNA / RNA, concentration of drug metabolites, pre- and post-treatment of liquid chromatography, concentration of immunoglobulin, etc.
advantage:
A large amount of safe sample processing. A variety of centrifuge tubes can choose to deposit samples on the bottom of the centrifuge tube, which can be recovered well to minimize foaming and cross-contamination. The heating efficiency can be improved by infrared mode. The vacuum degree is accurately controlled. :
The speed is slow. The visibility of the evaporation process is limited. The principle of the freeze dryer: the water in the pre-frozen sample is directly sublimated in a vacuum state. The cold trap can be used to capture the evaporated gas to make the evaporation process proceed quickly.
Application: drying of temperature- and oxygen-sensitive biological samples such as strains, vaccines, proteins, nucleic acids, drugs, etc. The lyophilized samples are easy to store and transport.
advantage:
Safety The moisture removal rate is very high. The vacuum is low, which can be accurately controlled. The sample temperature is low. It is suitable for temperature sensitive samples. It can maintain the sample properties and good resolubility. The shelf heating temperature can accurately control the disadvantages:
Slow speed, generally need to be processed overnight, the purchase cost is higher, the sample needs to be frozen in advance
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