This experiment is from the official website of College of Chemistry, Qingdao University of Science and Technology.
Operation method
Determination of C, H, N, and S in samples by elemental analysis
Principle
Elemental analyzer CHNS mode of operation is to make the sample in a pure oxygen environment in the corresponding reagent combustion, in order to determine the content of carbon, hydrogen, nitrogen and sulfur in organic matter. Specifically is the use of vertical combustion tube, the material to be measured with tin / silver boat package, placed on the automatic sample feeder, using the principle of gravity, regularly add 1000 ℃ or so combustion tube, injected with oxygen, the use of oxidation catalysts such as copper oxide and other oxidizing deposits and tin combustion to make the sample combustion temperature as high as 1800 ℃, prompting the sample to burn completely after the copper reduction process to generate the CO2, H2O, N2 and SO2 gas mixture in the carrier gas helium transmission, through a special separation tube using the principle of gas chromatography separation, and then the use of thermal conductivity detector (TCD) to determine its content, and then by the data processor calculations, can be automatically listed in the carbon, hydrogen, nitrogen, sulfur, the weight percentage. The sample analysis flow chart is as follows: Move boot-up procedure Caveat 1. For the accuracy of measurement, when wrapping the sample with the tin boat, care should be taken to squeeze out the air;2. The door of the combustion unit should not be opened freely during the analyzing process, so that the quartz combustion tube will not be cold suddenly and the life will be shortened;3、 The combustion products of fluorinated fluorine compounds will seriously corrode the wall of the gas line and shorten the service life of the instrument, so it is not suitable for elemental analysis. For more product details, please visit Aladdin Scientific website.
Turn on the computer, enter the WINDOWS state, pull out the two plugs of the host exhaust will be the host of the sample tray to one side to open the host power, to be the base of the sample tray self-test is completed that is, rotate one week, the sample back to the original place.
Turn on the helium and oxygen, the gas pressure reducing valve to: He: 0.2 MPa; O: 0.25 MPa start WINVAR operating software.
Operation program
Select the sample STANDARD
Enter the dialog window of the standard, input the name of the standard.
SULPHANILIC ACID Benzenesulfonic acid, can be abbreviated as SUL Enter the theoretical value of CHNS% and select FACTOR SAMPLE for the calculation of the correction factor.
Select CALIBRATION SAMPLE for calibration curve calculation.
Routine analysis
Instrument warming A
Enter the OPTIONS function, enter the PARAMETERS function.
Enter the operating temperature: Furnace 1: 1150 °C; Furnace 2: 850 °C; Furnace 3: 0 °C Instrument warming B (helium saving mode)
Enter SLEEP/ WAK UP function
Activate the ACTIV REDUCE GASFLOW function.
Enter 10 in the ACTIVE REDUCE GAS FLOW field.
To activate the SLEEP NOW function
After the temperature has risen to the specified temperature, enter the SLEEP/ WAK UP function again to activate the WAKE UP function.
or activate the AUTO function directly
Input of sample weight and name
Enter the EDIT editing function and then the INPUT function.
Enter the name of the sample in the NAME field, enter the weight of the sample in the WEIGHT field, and recommend the order in which the sample should be measured (CHNS mode).
1 blank
3 RUN-IN (without weighing the sample, approx. 2-3 mg)
3 SUL benzenesulfonic acid (weighed, approx. 2-3 mg range)
20 samples (weighed according to the nature of the sample)
2 SUL (benzenesulfonic acid, weighed, approx. 2-3 mg range)
20 samples (weighed according to the nature of the sample)
2 SUL (benzenesulfonic acid, weighed, approx. 2-3 mg range)
20 samples (weighed according to the nature of the sample)
Calibration of standard samples
Check if the data of the 3 samples are parallel, if they are parallel, enter the MATH function and activate the FACTOR function. If the data of one of the 3 samples are not parallel, enter the EDIT function, then enter INPUT and activate the TAGGED function on the two samples.
If one of the three samples is not parallel, enter EDIT, then INPUT, and activate TAGGED on both samples, then enter MATH, then enter FACTOR SETUP, activate COMPUT FACTORS FROMTAGGED STANDARDS (with #), and then activate the FACTOR function in the MATH function, and then activate the FACTOR function in the MATH function, and then activate the FACTOR function in the MATH function, and then activate the FACTOR function in the MATH function.
If you analyze the sample for the second time, and if the data of the three samples are parallel, the FACTOR SETUP function is resumed, i.e., the FACTOR SETUP function is activated in this function.
COMPUTE FACTOES SEQUENTIALL
Analytical cycle start
Entering the SLEEP/ WAK UP function and activating the ACTIVE SLEEP TEMPREATURES function activates OK, which automatically puts the sample to sleep after the analysis is finished.
Activate AUTO to analyze the sample.
Shutdown program
After the analysis, the mainframe automatically enters the sleep state, until the temperature is reduced to below 750 ℃ to exit the WINVAR operating software (system-offline-exit), shut down the computer to shut down the mainframe, open the mainframe combustion unit door to dissipate the residual heat.
Turn off the helium and oxygen, and block the two outlets of the exhaust gas of the mainframe.