Kjeldahl Nitrogen Analyzer is an instrument that calculates the protein content by measuring the nitrogen content in the sample based on the principle of constant nitrogen content in protein. The automatic Kjeldahl nitrogen analyzer is a commonly used equipment in the laboratory, mainly used for protein test. It consists of four basic parts, namely distillation device, titration device, detection device, and waste discharge device. Each device can have an impact on the test results, therefore, it is necessary to do a good job in the maintenance of each device.
 
I. Distillation device
1. Cleaning
After the sample is measured, add 80 liters of water and start steam distillation for 5 minutes to clean the distillation device. After cleaning, remove the digestive tube, and pour out the contents, then wipe the safety door and drip tray to remove the residual alkali liquor during the measurement process.
2. Replace the rubber head
During the distillation process, the hot alkali liquor has a corrosive effect on the rubber head of the distillation device. After long-term use, the rubber head and the digestive tube will not be well sealed, which will cause the free amine to leak and affect the measurement results. Therefore, the rubber head should be checked regularly, and if it is found to be severely corroded, it should be replaced immediately.
 
II. Titration device
1. Cleaning
After the test is completed, clean the titration vessel and the liquid level probe to prevent the residue of the reception liquid from adhering to the inner surface of the titration vessel  and affect the next measurement.
2. Replace the standard acid solution
When using standard acid solutions of different concentrations, the residual acid liquor in the titrator of the instrument should be removed. The method to remove the acid liquor is to open the front cover of the instrument first, and the instrument will give an alarm, prompting that the front cover is opened, then find a small magnet and put it on the contact on the front of the instrument, and then press the Enter key on the panel, and the front cover of the instrument is closed by default. Next Select the titrator filling function of the instrument, the titrator piston moves upwards, and when it stops, select the titrator emptying function, and the titrator piston moves downwards. Repeat 3~5 times like this, the old acid liquor will be replaced by the new one.
 
III. Waste discharge device
1. Cleaning
Clean the waste discharge device regularly. If it is not cleaned for a long time, the pipeline will be blocked. Take 25ml acetic acid solution and 5ml water, and distill for half an hour, then the volatile acetic acid will remove the residual alkali liquor on the inner wall of the waste discharge device.
2. Repair
If the waste discharge device is blocked, it is generally because the solenoid valve under the waste liquid tank is blocked by carbonized particles. In this case, turn off the power switch of the instrument, open the back cover, remove the solenoid valve, clean the internal waste after disassembly, and then install it.