Accurate digestion in one step: CEM microwave digestion instrument usage steps disassembly and safety specification manual

CEM Microwave Digestion InstrumentUsage process

CEM microwave digestion instrument is the core equipment for laboratory sample pretreatment, which utilizes the penetration and uniformity of microwave heating to achieve rapid and efficient digestion of samples. It is suitable for heavy metal and trace element analysis in multiple fields such as food, environment, medicine, geology, etc. The standard usage process is as follows:

sample pretreatment

Weigh an appropriate amount of sample according to the testing requirements (usually 0.1-1.0g for solid samples and 1-5mL for liquid samples, adjusted according to the sample matrix and equipment requirements), and place it in a clean PTFE digestion tank.

Add suitable digestion reagents for different samples, such as nitric acid (HNO3), hydrochloric acid (HCl), etc. The amount of reagents added should strictly follow the equipment regulations, generally not exceeding 1/3 of the digestion tank volume.

If the sample contains organic substances or is prone to gas production, it needs to be pre digested: covered and left to stand at room temperature or heated at low temperature, and then sealed after the violent reaction stops.

Sealing and assembly of digestion tank

Select a intact sealing ring for the digestion tank, ensuring no damage or deformation. Cover the digestion tank tightly and tighten it according to the equipment operating instructions (with moderate force, too loose may cause leakage, and too tight may damage the tank body).

Place the assembled digestion tank into the turntable bracket according to the principle of symmetry, ensuring even load distribution and avoiding one-sided bias; If the sample quantity is insufficient, an empty digestion tank should be filled with an equal amount of water for balance.

Equipment parameter settings

Turn on the instrument power, enter the operation interface, select the corresponding digestion program template (such as food digestion, soil digestion), or customize parameters:

Power: Adjust according to sample size and reagent type, generally between 600-1500W;

Heating program: Set multiple heating gradients (such as room temperature → 120 ℃ → 180 ℃), with each heating period lasting 5-20 minutes, to avoid rapid heating that may cause a sudden increase in pressure inside the tank;

Insulation time: Set according to the difficulty of sample digestion, usually 10-30 minutes;

Pressure protection threshold: set according to the pressure resistance value of the digestion tank to prevent overpressure risk.

Start operation and monitoring

After confirming that the digestion tank is in place and the furnace door is closed and locked, click the "Start" button, and the instrument will automatically run the digestion program.

During operation, monitor the temperature and pressure data displayed on the screen in real-time. If any abnormalities occur (such as sudden pressure rise or temperature not meeting the standard), immediately pause the program and troubleshoot the problem.

subsequent processing

After the program runs, the instrument will automatically cool down or manually select the cooling mode (natural cooling or forced cooling). The furnace door can only be opened when the temperature inside the tank drops below 50 ℃ and the pressure approaches atmospheric pressure.

Slowly unscrew the lid of the digestion tank for exhaust, transfer the digestion solution to a volumetric flask, wash the digestion tank multiple times with ultrapure water, combine the washing solutions to make up the volume, shake well, and wait for testing.

Precautions for using CEM microwave digestion instrument

Microwave digestion equipment involves high pressure, high temperature, and highly corrosive reagents. Improper operation can easily cause liquid leakage, equipment damage, and even safety accidents. The following precautions should be strictly followed:

（1） Core points of safe operation

Taboos for the use of digestion tanks

The digestion tank, sealing ring, and lid must be used together, and it is strictly prohibited to mix different models or damaged components (cracked or deformed digestion tanks may cause microwave leakage or explosion risks).

Do not place the digestion tank directly on an open flame or high-temperature equipment to avoid aging of the tank body.

Reagent and sample control

Samples containing perchloric acid (HClO ₄) should be handled with caution, and direct digestion in a microwave digestion apparatus is strictly prohibited (perchloric acid is prone to explosion at high temperatures). It should be pre digested with nitric acid to remove organic matter before use.

Samples that are prone to producing large amounts of gas, such as carbonates and sulfides, must be thoroughly pre digested and it is strictly prohibited to directly heat them up after sealing.

The amount of reagent added should not exceed one-third of the capacity of the digestion tank to prevent pressure exceeding the standard due to heating expansion.

Equipment operation safety

When the furnace door is not closed and locked, the instrument cannot be started; It is strictly prohibited to open the furnace door during operation. In case of emergency, immediately press the "emergency stop" button.

Operators need to wear protective equipment (acid and alkali resistant gloves, goggles, lab coats) to avoid contact with high-temperature digestion tanks and corrosive reagents.