Microwave digestion instrument can be widely used in pharmaceutical, biological, food, chemical, environmental, textile, plastic, metallurgical and other fields, used for sample pretreatment, the emergence of intelligent microwave digestion instrument, well meet the requirements of modern instrument analysis for sample pretreatment process, not only fast processing speed, but also low energy consumption, can maintain the integrity and rate of the sample as much as possible.
How the microwave digester works.
Under the action of microwave electric field, the positive and negative directions of the microwave electrolyzer are constantly changed at a very high rate, so that the molecules produce high-speed collision and friction and produce high heat, and at the same time, under the action of the microwave electric field, the ions in the solution system flow directionally to form an ion current, and the ions have high-speed friction and collision with the surrounding molecules and ions in the flow process, so that the microwave energy is converted into heat energy.
Microwave digester temperature control mode.
The temperature control methods of the intelligent microwave digestion instrument include infrared temperature control, thermocouple temperature control, platinum resistance temperature control, optical fiber temperature control and other temperature control methods.
1. The working mode of infrared temperature control is to scan and monitor the temperature infrared data at a certain distance, which is non-contact temperature control, so its performance is poor, and the temperature control accuracy is not high
2. The thermocouple temperature control is tested by the potential difference between the cold and hot ends, which is easy to cause the antenna effect to interfere with the uniformity of the microwave field, so it is easy to produce electric sparks and cause safety accidents. And there is a self-heating effect under the microwave field, that is, the actual temperature in the tank cannot be determined;
3. Platinum resistance temperature control is a conductivity technology that uses changes to affect the free electron beam in platinum conductors to test the thermodynamic temperature through impedance changes, and the output signal response is high. However, there will also be an antenna effect, which is easy to produce electrical sparks and cause safety accidents
4. The optical fiber temperature control adopts the direct optical fiber temperature measurement method, which is not affected by the microwave field, can provide high-precision measurement, has timely information feedback, temperature control, and no potential safety hazards, which is the ideal microwave digestion and temperature control method at present.
Microwave Digester Notes:
The microwave digestion instrument must be grounded, otherwise there may be accidents such as ignition.
Each digestion vessel should contain the same sample and solvent type, and the sample quality, solvent volume, and starting temperature should also be the same, including tank zero, which is conducive to temperature and pressure control. The serial numbers of the digestion inner tank, outer tank, and bracket should also be the same, and should not be mixed to prevent air leakage.
During operation, the set pressure and temperature should not exceed the maximum value specified by the instrument, so as not to damage the digestion tank and other accessories.
After the salt worker is loaded into the digestion tank, the tank lid should be tightly closed and the filling mouth of the digestion tank should be ensured to enter the notch of the sealing cap, and then the sleeve should be put into the sample dissolution cup, put it into the frame, and tighten the top wire by hand and tighten it with a torque wrench.
The connection between the lower joint of the air duct and the control tank must be tightened to ensure that there is no air leakage here, otherwise the leaked acid gas will cause ignition and combustion accidents and damage the machine. If ignition is found in the experiment, it should be stopped immediately.
After the digestion process is completed, all digestion tanks must wait for the temperature to drop before they can fully loosen the gas screws in the fume hood, and only after the gas in the tank is released can the top wire be loosened and the digestion tank can be taken out, otherwise the operation will cause the acid in the tank to splash and hurt the experimenter