1. Overview:

This series of Kjeldahl nitrogen analyzers is based on the internationally recognized Kjeldahl nitrogen determination method (named after Kjeldahl), which heats catalysts such as sulfuric acid and materials together to decompose and free nitrogen-containing organic compounds in proteins through physical heating. The decomposed acidic substances react chemically with nitrogen-containing compounds in proteins, ultimately producing (NH4) 2SO4 ammonium sulfate. By adding alkali and acid to the equipment, ammonia is dissociated and decomposed in a distilled state, and finally cooled and collected in a low-temperature condenser tube. Simply put, the Kjeldahl nitrogen analyzer is a device used to detect the protein content in the substance being tested. Simply put, the operation process involves sampling, digestion, distillation, and finally calculating the results. The Jinlan series Kai type nitrogen analyzer is used in combination with a porous digestion furnace and a nitrogen analyzer host, which is different from the fully automatic Kai type nitrogen analyzer. Widely applicable to grain, food, dairy products, beverages, feed, soil, water, medicine, sediment, and chemicals, etc

2、 Host architecture:

3、 Product features:

1. Thickened spray coated cold-rolled steel shell, with an overall transparent tempered glass box door. Long service life of rust resistance, convenient for observing the experimental process.

2. Built in multiple software alarms, automatically detecting the current water level; When there is a shortage of water or the water level line is too low, or when the water level detection system fails, it will automatically remind the user;

If a malfunction occurs during equipment operation, the software control system will automatically cut off the input power supply.

3. Add a safety door to the digestive tract.

4. The whole machine is controlled by a microcomputer, so there is no need to repeatedly set operating parameters.

Automatic water inlet, automatic water level control, automatic distillation, and automatic water stop.

5. The addition titration is blocked, and the operation is stable with high accuracy.

4、 Technical parameters:

Water sources: distilled water and natural water.

Detection range: 0.1-200mg/N (milligrams/nitrogen)

Sample size: Solid state: 0.2~2g;

Semi solid state: 2~5g;

液体： 10~25ml；

Working mode: semi-automatic;

Recovery rate: ≥ 99% (relative error, including digestion process)

Distillation rate: 5-15 minutes per sample (depending on sample size specifications)

Repetition rate:<± 1% (relative standard deviation)

Whole machine power (W): 1000

Power supply voltage: AC220V, 50Hz

Note: Water pressure>1.5Mpa; Water temperature<25 ℃;

5、 Operation steps:

1. Preparation before operation:

① Turn on the red alkali switch;

② Turn on the red distillation switch;

③ Select a suitable conical flask (around 205ml) with a glass stopper based on the concentration of the test substance and the current operating environment temperature (make sure to immerse the glass nozzle below the reagent liquid level during operation to prevent ammonia gas from escaping and affecting the accuracy of the results);

④ Close the organic glass cover on the device and tightly seal it with the upper magnet to prevent the alkali from escaping.

⑤ Press the tray below the digestive tract (diameter 45 * 300) to install, disassemble, and adjust the digestive tract.

⑥ Observe the water level observation hole of the host heating cup, check the height of the water level inside the heating cup, and check for water shortage or overflow.

⑦ After installation, check the airtightness above the equipment.

2. Accessories:

① Cut the silicone tube with a diameter of 4 to the desired length, insert one end into the alkali inlet and the other end into the container for alkaline test solution.

Cut the silicone tube with a diameter of 6 into four sections and trim it to the appropriate length.

Follow the first step to immerse one section of the four silicone tubes into distilled water inlet, distilled water outlet, cooling water inlet, and cooling water outlet respectively, and the other end into distilled water, waste liquid, and water source respectively.

3. Consumables and samples:

① One ten thousandth electronic analytical balance; 25ml, 10ml acid burette; 250ml conical flask;

② NaOH: prepared as a 40% concentration aqueous solution (chemically pure);

H3BO3 (boric acid): prepared as a 2% concentration aqueous solution (analytical grade);

HCl hydrochloric acid: 0.05mol/L standard solution, using sodium carbonate to calibrate hydrochloric acid (analytical grade);

Mixed indicator: G5H5N302 (methyl red), dissolved in ethanol to prepare a 0.1% concentration ethanol solution, bromocresol green dissolved in ethanol to prepare a 0.5% concentration ethanol solution (equal volume mixed and stored in a cool place for no more than three months);

③ After the digestion is completed in the digestive furnace and cooled, dilute it before conducting the experiment.

4. Specific operation:

① Open the water inlet and control the water flow rate at around 3-4L/min. Turn on the device power, and the nitrogen analyzer will start automatically injecting water. (Pay attention to the water level observation port of the heating cup)

② Turn on the alkali addition switch and control the injection of alkali to around 30ml.

③ After adding alkali, turn on the distillation switch. Turn on for about 10 minutes, and the liquid in the conical flask should be at least 100ml and at most 150ml before turning off the distillation switch.

④ The sample is placed on a digestive tray for digestion and cooled to dilute. 20ml of distilled water is added for dilution, and then transferred to the conical flask prepared on the right. 4-5 drops of mixed indicator and 50ml of boric acid are added.

⑤ Distillation is almost complete (about 8-12 minutes, liquid in the conical flask is about 150-200ml), lift the rubber stopper, move the conical flask away, and the glass nozzle is off the liquid surface.

⑥ Rinse the outer wall of the glass nozzle with distilled water, keep the distillation on for about 10 seconds, turn off the distillation button, remove the conical flask and wait for titration.

⑦ Titrate the solution in the receiving bottle with 0.05mol/L HCl until it turns (dark) gray, and record the amount of HCl consumed in ml.

6、 Reaction equation:

① Distiller: (NH4) 2SO4+2NaOH (high-temperature steam)=2H2O+2NH3 ↑+Na2SO4;

2NH3+4H3BO3=(NH42BO4O7+5H2O

The sample is placed in the digestive tract and converted into water vapor and NH3 under the high temperature and alkaline chemical reaction of the equipment. It is collected in the H3BO2 test solution in the container;

②、滴定部分： （NH4）2B4O7+H2SO4+5H2O=(NH4)2SO4+4H3BO3;

( NH4 ) 2B4O7+2HCl+5H2O=2NH3Cl+4H33BO3;

(In a titrator, standard concentration H2SO4 or HCl is used for titration, and the protein content is detected by multiplying the remaining nitrogen content after the reaction in H2SO4 or HCl by the corresponding conversion factor.)

③ Digestive tract: Ammonium ions in organic matter undergo nitrification to form (NH4) 2SO4 under the reaction of catalyst, high temperature, and H2SO4

2NH2+H2SO4+2H=(NH4)2SO4

7、 Attention:

1. The connections of the distiller, inlet and outlet should be tight to prevent leakage.

2. Clean the components using a 10% concentration NaOH solution, boil for about 10 minutes, wash with water and boil for 10 minutes, then wash with water several times, and cool dry in a ventilated and cool place.

3. Keep the glass nozzle immersed below the reagent liquid level.

4. The color of the alkaline dosage meter reagent turns black as the standard.

5. When replacing the sample for distillation, there is no need to turn off the main power switch.