Microwave digestion system refers to an instrument system that uses the principle of microwave heating in a closed container to achieve the purpose of sample pretreatment under high temperature and high pressure conditions. Microwave digestion system is generally composed of host computer, optical fiber temperature monitoring system, precise pressure monitoring system, abnormal temperature and pressure monitoring system, digestion tank and rotor system, software system and other systems.
Microwave digestion, as an efficient sample pretreatment method, can well meet the requirements of modern instrument analysis for sample pretreatment process.It has the advantages of fast heating speed, uniform heating, less reagent consumption, low blank, energy saving and high efficiency. Especially in the analysis and detection of volatile elements, the integrity of the sample can be well maintained, and the sample recovery rate is very high.
Microwave digestion instrument has been widely used in food, textile, plastic, geology, metallurgy, coal, biomedicine, petrochemical, environmental monitoring, sewage treatment, battery manufacturing, cosmetics and other fields.
Microwave digestion temperature control methods include infrared temperature control, thermocouple temperature control, platinum resistance temperature control, optical fiber temperature control, etc. The working method of infrared temperature control is to scan and monitor temperature infrared data at a certain distance. It is a non-contact temperature control, so its accuracy is poor and the temperature control accuracy is not high.
Thermocouple temperature control means that the sensor measures the relative temperature through the potential difference between the hot and cold ends.Because the antenna effect is likely to interfere with the uniformity of the microwave field, it is easy to generate electric sparks and cause safety accidents, and there is a self-heating effect under the microwave field, which means that the tank cannot be measured actual temperature.
Platinum resistance temperature control uses temperature changes to affect the absolute conductivity of platinum conductors, and tests thermodynamic temperature through impedance changes. The output signal has a strong response and high precision. But there will also be an antenna effect, which is easy to generate electric sparks and cause safety accidents. Optical fiber temperature control adopts direct optical fiber temperature measurement method, which is not affected by the microwave field, can provide high-precision measurement, has the advantages of timely information feedback, accurate temperature control, and no potential safety hazards.It is the most ideal microwave digestion temperature control method.
(1) Using a high-precision temperature and pressure control system, the operator can understand the operation of the machine by observing the data and curves of temperature and pressure changes.Its software module can actively stop the operation when the slope is out of control, which greatly reduces the possibility of explosion.
(2) Equipped with a real-time temperature and pressure abnormal monitoring system. When the high-precision temperature and pressure control system fails, the microwave digestion system will sense and stop operation in time as a backup measure to ensure safety.
(3) Choose high-strength and high-temperature-resistant container materials.