Kjeldahl Nitrogen Analyzer FAQ Guide: Everything the lab owners and researchers need to know.
The determination of protein content in food is a difficult problem to solve, but nitrogen content is easier to measure. Therefore, we can measure the nitrogen content to calculate the protein content. Usually, we use the supplier CIALAN Kjeldahl nitrogen analyzer to measure the nitrogen content. And this article lists all the frequently questions and answers about protein analysis techniques-Kjeldahl nitrogen analyzer machine, including the classification of nitrogen analyzer, the working principle, and supporting equipment etc. We hope it will help you to buy a suitable kjeldahl digestion and distillation apparatus.
What Is Kjeldahl Method?
In 1883, Johan Kjeldahl revolutionized nitrogen analysis by proposing a "new method for determining the nitrogen content of organic matter". This method has become the standard for food (cereals, dairy products), feed, soil (compost), water (water extracts and wastewater), industry (slurries, sewage sludge), the pharmaceutical industry, and any field where nitrogen content is important. In addition to the total nitrogen content, individual components such as ammonium, nitrate, nitrite and organically bound nitrogen can be determined from various sample matrices.
What Is a Kjeldahl Nitrogen Analyzer?
The Kjeldahl Nitrogen Analyzer is an instrument for quantitative analysis of elemental nitrogen in organic and inorganic samples by the Kjeldahl method.
What Is The Principle Of Kjeldahl Nitrogen Analyzer?
The working principle of the Protein Analyzer is mainly based on the Kjeldahl method.
The sample is heated and digested with concentrated sulfuric acid and a catalyst, and the organic nitrogen in the sample is converted to ammonium sulfate. Distillation under alkaline conditions releases the ammonia. The ammonia is titrated with an acid or base solution and the nitrogen content of the sample is calculated from the amount of acid or base consumed in the titration.
What Is The Function Of Kjeldahl Nitrogen Analyzer?
Kjeldahl Distillation Apparatus is mainly used for the determination of ammonia nitrogen, protein nitrogen, phenol, volatile fatty acids, cyanide, sulfur dioxide, ethanol, etc. in food, feed, dairy products, beverages, feed, soil, water, medicines, sediments and chemicals.
What Is The Cost Of Kjeldahl Nitrogen Analyzer?
The price/cost of a kjedahl distiller is about 800-55000usd/set.
To know the exact price, you can ask your preferred kjedahl nitrogen analyzer manufacturer to provide a quotation for the type you want.
What Are The Limitations Of The Kjeldahl Method?
The Kjeldahl analysis method can only determine nitrogen and ammonium bound to organic components (proteins, amino acids, nucleic acids) in the sample. It is not suitable for the detection of nitrogen in azo, nitro or cyclic nitrogenous compounds (quinoline, pyridine, nitrates and nitrites, etc.), which cannot be converted to ammonium sulphate according to the protein analysis Kjeldahl method.
The Common Problems And Solutions For Kjeldahl Nitrogen Analyzer?
1. Problem: Cannot add acid and alkali solution during titration.
Solution: It may be due to the acid and alkali liquid is too little, the inlet pipe left the liquid level, need to make up liquid in time.
2. Problem: Acid and alkali barrel no pressure.
Solution: It may be due to the acid and alkali pipeline or air pump leakage, damage, need to replace the pipeline or air pump in time.
3. Problem: Acid and alkali barrel pressure, but can not add liquid.
Solution: It may be due to the solenoid valve power is not connected or the solenoid valve internal crystallization clogging pipeline, we need to check the solenoid valve wiring or dismantle the solenoid valve in time.
4. Problem: The precision of measurement is poor.
Solution: When the instrument is used for a long time, the scale on the heater should be cleaned in time to ensure good heating efficiency; when it is not in use, the distiller should be cleaned in time and the sediment in the acid and alkali bucket should be cleaned.
What Is The Components Of Kjeldahl Nitrogen Analyzer?
Digestion furnace: The sample is boiled with accelerant, catalyst and concentrated sulfuric acid at 380-400 degrees Celsius in a digestion tube to produce ammonium sulfate;
Distiller: The ammonium sulfate obtained from the above mentioned digestion tube is distilled by adding distilled water and alkali, the ammonia obtained is collected in a receiving bottle;
Titrator: Ammonia in a standard acid bottle is titrated with standard alkali;
Calculation: The nitrogen and crude protein content are calculated according to the results of the titration.
What Is The Classification Of Kjeldahl Nitrogen Analyzer?
Protein nitrogen analyzers are generally divided into semi-automatic Kjeldahl nitrogen analyzer, automatic Kjeldahl nitrogen analyzer and fully automatic Kjeldahl nitrogen analyzer according to the automation.
Semi-automatic Kjeldahl nitrogen analyzer, as the name suggests, is operated manually.
Automated Kjeldahl nitrogen analyzer can automatically add alkali automatic distillation automatic recovery of liquid than manual a little more convenient, but also more secure, after all, to avoid contact with strong alkali.
Fully automatic Kjeldahl nitrogen analyzer can automatically add alkali, automatic distillation, automatic recovery, automatic titration, one-step completion of the analysis, saving a lot of labor and time at the same time also try to avoid the error brought about by human operation.
What You Need To Pay Attention To When Using Kjeldahl Nitrogen Analyzer？
Start-up measurement: The protein analysis equipment's water is neutral deionized water; the standard acid used for titration must be prepared and calibrated according to the standard. Before testing the sample, the instrument should be opened to preheat, put a digestion tube empty steam once, to exclude the air in the distillation line.
Sample pre-treatment: Samples should be selected as representative as possible, large solid samples should be crushed equipment to play fine and uniform, liquid samples should be mixed evenly.
Modular digestion device to digest samples: Digestion process, first of all, to ensure that the amount of concentrated sulfuric acid is sufficient; secondly, to ensure that some of the samples are not easy to produce foam when carbonized.
How Does a Kjeldahl Nitrogen Analyzer Work?
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1. Turn on the machine: Open the water valve, then turn on the power of the main unit, then the machine starts self-test.
2. Pre-heat: Put in the empty digestion tube, click preheat, about 3-5 minutes, after finishing, take out the digestion tube.
3. Setting: "Tools"- "Analyze Data" - "Programs" - -Select and edit the program as needed.
4. Analyze and measure: Click "Analyze", click "Start" in the lower right corner to analyze in order.
5. Shutdown cleaning: After the safety door is opened, clean the instrument - wipe the distillation head, test tube connector, the inside of the safety door with a wet rag, and carefully remove the bottom tray for cleaning.
6. Shutdown: Turn off the power to the instrument and close the water valve.
How To Maintain a Kjeldahl Nitrogen Analyzer?
1. When the sample has been measured, the distillation unit needs to be cleaned. After cleaning, remove the digestion tube, pour out the contents, and wipe the safety door and drip tray.
2. Regularly check the rubber head and replace it immediately if serious corrosion is found.
3. Clean the titration cylinder and level probe after the test is completed to prevent the residue of the receiving liquid from adhering to the inner surface of the titration cylinder and affecting the next measurement.
4. When using standard acid solutions of different concentrations, the residual acid in the instrument titrator should be removed.
5. Clean the exhaust device regularly (generally about as a cycle), long time without cleaning, will clog the pipeline.
6. Turn off the power switch of the Kjeldahl Protein Analyzer, open the back cover of the instrument, remove the solenoid valve, disassemble it, remove the internal waste and install it.
What Is The Application Of Kjeldahl Nitrogen Analyzer?
Kjeldahl nitrogen and protein analyzer is suitable for grain and oil testing, feed analysis, plant nutrient testing, soil fertility testing, environmental protection, medicine, tobacco, chemical and other industries, teaching and scientific research.
What Is The Supporting Equipment For Kjeldahl Nitrogen Analyzer?
Acid-base neutralization device: The sample digestion process produces a large amount of acid mist, which can seriously pollute the environment and damage facilities. This device is the best instrument for collecting, neutralizing and filtering acid mist.
Exhaust gas collection device: This collection device is an acid gas collection device specially designed for digestion furnaces.
Constant temperature heating digestion furnace: The digester is a sample digestion and transformation equipment developed according to the classical wet digestion principle.
Jet type negative pressure pump: The negative pressure sucks the acid mist in the waste gas collector and discharges it into the sewer together with the water flow.
What Is The Difference Between Dumas Method And Kjeldahl Method?
Different principles:
Kjeldahl method: In the presence of catalyst, with concentrated sulfuric acid digestion of the sample will be organic nitrogen are converted into inorganic ammonium salts, and then in the alkaline conditions will be converted into ammonia salts, with the distillation of water vapor and absorbed by an excess of boric acid, and then the standard hydrochloric acid titration, the nitrogen content in the sample can be calculated.
Dumas Nitrogen Method: Also known as combustion nitrogen determination, the sample is burned at high temperature, so that the organic nitrogen is converted to nitrogen, and then determine the nitrogen content of the sample by detecting the amount of nitrogen.
Different operation process:
Kjeldahl method: The operation is relatively complex, including sample digestion, distillation, titration and other steps.
Dumas Nitrogen Analyzer: The operation is relatively simple, the sample will be burned, through the instrument to automatically detect the nitrogen content.
Difference in accuracy:
Kjeldahl Nitrogen Determination: Statistical evaluation of experimental data shows that Kjeldahl Nitrogen Determination is generally more accurate.
Dumas Nitrogen Determination: The standard deviation is relatively small.
Different detection efficiency:
Kjeldahl method: Lower detection efficiency. For example, in the detection of crude protein content in feed, Kjeldahl method is less efficient.
Dumas Nitrogen Determination: Easy to operate, high detection efficiency.
Different scope of application:
Kjeldahl method: For soil samples with nitrogen content ranging from 0% to 0.06%, the results of Kjeldahl method are closer to the real value.
Dumas Nitrogen Determination: It is feasible to be used for the detection of proteins in liquid dairy products. For soil samples containing more than 0.06% nitrogen, the Dumas combustion method is more suitable.
What Is Kjeldahl Method Cannot Be Used For?
Kjedahl method distillation is not suitable for the detection of nitrogen in azo, nitro or cyclic nitrogenous compounds (quinoline, pyridine, nitrates and nitrites, etc.), which cannot be converted to ammonium sulphate according to the Kjeldahl method analysis.
What Is The Calibration Of Kjeldahl Nitrogen Analyzer Repeatability?
Repeatability of kjeldahl digestion and distillation apparatus measurement can test the reliability of the measurement results, is a calibration project of protein nitrogen analyzer. The calibration method of measurement repeatability is to weigh 0.2 g of dried high purity money sulfate, distill and titrator according to the operation procedure, and calculate the recovery rate. Repeat the measurement six times, calculate the relative standard deviation RSD (%) as the measurement repeatability of the instrument, the result should be less than or equal to 3%.
How To Eliminate Air Bubbles In The Titrator Of a Kjeldahl Nitrogen Analyzer？
The problem of air bubbles can be solved by first taking the hydrochloric acid solution out of the hydrochloric acid delivery line and then filling the titrator in manual mode. Since the piping is not placed in the hydrochloric acid solution, the titrator can only inhale air when charging the titrator, and the bubbles in the buret will disappear into the air, and then put the piping back into the hydrochloric acid solution to empty the titrator and charge the titrator again, which can eliminate the air bubble problem.
Kjeldahl Nitrogen Analyzer Tumbles Violently During Distillation, Will It Be Dangerous To The Operator?
Not dangerous, Kjeldahl nitrogen distillation unit tumbles violently during distillation, is a large amount of water vapor into the digestive tube liquid tumbles, is not caused by violent reaction; and the instrument has an overpressure protection device, which can maintain atmospheric pressure inside the pipeline to avoid danger.
What Is The Water Quality Requirement Of Kjeldahl Nitrogen Analyzer?
The distilled water bucket of the Kjeldahl Nitrogen Determination Instrument should be filled with distilled or purified water, and if the machine is not used for a long period of time, the water should be drained from the distiller.
Why Does The Kjeldahl Nitrogen Analyzer Turn On Without Sound?
Kjeldahl nitrogen analyzer power on no sound, if the machine power switch within the red light, indicating that the nitrogen analyzer fuse burned out.
Kjeldahl Nitrogen Analyzer Does Not Add Water In The Distiller When The Power On How To Solve?
Power on half a minute to check whether the distilled water bucket leakage, can be filled with gas drum is normal.
Distilled water level should be more than one-third of the bucket, the position is higher than the placement of the instrument's countertop, distilled water bucket into the air, into the liquid pipe is connected correctly, the drain valve should be closed;
Why Kjeldahl's Nitrogen Apparatus Does Not Heat The Pot Does Not Produce Steam?
If the kjeldahl distillation system can add alkali normally, can not be heated out of steam, determine the heating wire may be burned out.
If the kjeldahl distillation can't add alkali normally, and there is no sound after powering on the machine, the judgment is that the fuse is blown.
Is It Normal For Kjeldahl Nitrogen Tester To Sound Loud When Working?
Normal phenomenon, this is the sound of the nitrogen protein analyzer's internal air pump work.
Why Kjeldahl Nitrogen Tester Can Not Add Alkali In The Work, And Add Alkali No Sound?
Check whether the alkali drum is leaking, the machine can work normally only when it is filled with gas;
if the instrument is used for a long time, the alkali tube will be crystallized inside, and the flow rate will be reduced when adding liquid, and there is no sound.
When The Kjeldahl Nitrogen Analyzer Is Working, Why Does The Gas Like Smoke Come Out From The Top?
Check whether the water inlet of cooling water is open, the cooling water is closed or the amount of water is small will lead to the vapor out of the digestion tube can not be condensed, and the water vapor coming out of the kjeldahl machine is similar to smoke.
How To Solve The Problem When The Digestion Tube Is Full Of Water In The Nitrogen Analyzer?
Nitrogen analyzer use occurs in the digestion tube into the full of water, is due to the machine control water level device to reduce the conductivity caused by opening the water level device to take out the probe with sandpaper sanding, to remove the oxidized layer; in a bucket of distilled water to add 3-5 grams of laboratory sodium chloride, shaking well to dissolve.
The Use Of Kjeldahl Nitrogen Analyzer Occurs In The Distiller, Water Level Into The Full Of Water, Boric Acid Absorption Solution Container Into The Water, How To Solve?
Is the protein analyzer machine control water level device conductivity caused by the reduction of solutions: open the water level device to take out the probe with sandpaper sanding, to remove the oxide layer; in the distilled water bucket to add 3-5 grams of laboratory sodium chloride, shake well to dissolve.
Kjeldahl Nitrogen Analyzer Use In The Digestion Tube In The White Tube Occurs Backward Suction, How To Solve?
The nitrogen protein analyzer instrument stops working (the distiller stops heating), the gas valve fails to close in time, it will produce the phenomenon of backsorption, you can tie some small holes in the white tube. The valve is damaged and can not be closed, it will also be sucked back.
Kjeldahl Nitrogen Analyzer Work Every 3-5 Seconds Will Sound, Is It Normal?
This sound is a normal phenomenon, the kjeldahl method distillation is working, the distiller will continue to heat the water vapor and consume water, the instrument will automatically open the water valve to replenish water, the sound is the sound of the water valve is open, close the sound, is a normal phenomenon.
Why The Automatic Working State Can Not Continue To Work, Suddenly Stop?
This is due to the surrounding electric field interference with the computer, press the reset button or shut down and then reboot can be.
Why The Measured Value Is Not Stable Or Too High?
May be the steam generator is not clean, the steam generator will be emptied of water, replace the new water and then measured. Or too much liquid in the decoction tube, there is alkali rushed to the distillation system, then you can empty the distillation system and then make measurements.
