Here isFourier transform infrared spectrometerThe standard operation process covers the key steps and precautions from startup to data analysis
1、 Startup and initialization
Power on
Press the power switch of the instrument host and wait for the self-test to complete (about 10 seconds). When the status light turns blue, it indicates that the self-test has passed.
Preheating requirement: Wait for at least 20-30 minutes to ensure the stability of the light source and electronic components. Some models (such as Nicolet 6700) need to wait for sufficient and stable energy output from the light source.
Software startup
Turn on the computer and run the supporting operating software (such as OMNIC, GRAMS, etc.).
Check the communication status between the computer and the instrument host, and confirm that the connection is normal.
2、 Sample preparation
Select sample preparation method based on sample type:
Solid sample
KBr compression method: Take 1-2 mg of sample and mix it with dry KBr powder (about 100 mg), grind it, and press it into thin sheets with a light transmittance of>80%.
ATR attachment: Directly contact the solid sample with the ATR crystal surface, suitable for difficult to press or moisture absorbing samples.
Paste method: After grinding the sample, add liquid paraffin and mix well, then apply it onto KBr chips for testing.
liquid sample
Solution method: Dissolve the sample in an appropriate solvent (such as CCl ₄), inject it into a 0.1 mm liquid pool, and control the concentration at around 10%.
Liquid film method: viscous liquid is directly coated onto KBr chips; Low boiling point liquid is sandwiched between two KBr chips for testing.
Gas sample
Use a dedicated gas pool to ensure the sealing of the gas path and avoid leaks.
3、 Parameter settings
Experimental setup
Y-axis format: Select "Absorption".
Background management: Set to 'collect background before sample collection'.
Scanning frequency: It is recommended to scan at least 32 times to improve the signal-to-noise ratio.
Resolution: Solid/liquid samples are usually selected at 4 cm ⁻¹, while gas samples are selected at 2 cm ⁻¹.
Wave number range: Typical values are 4000-400 cm ⁻¹.
Optical table calibration
Check the energy value of the "optical table", the normal range is 6-8. If there is an abnormality, click "Diagnosis" to perform alignment correction (once a month).
4、 Background and sample collection
Background scanning
Place a blank KBr slice or empty bin, click on "Collect Background", and wait for the scan to complete (the diamond icon in the bottom left corner is all black).
Sample scanning
Quickly insert the sample, close the hatch, and click "Collect Sample".
Enter the spectrum title and wait for the scan to complete (approximately 1-3 minutes).
5、 Data Processing and Analysis
Baseline correction
Click on the 'Automatic Baseline Correction' icon to eliminate baseline drift.
Manual adjustment: Use the straight-line method, three-point method, or quadratic polynomial method to optimize the baseline.
Spectral conversion
Convert the vertical axis from absorbance to transmittance (% T) for easy observation of peak shape.
Peak marking and retrieval
Peak labeling: Automatically label peak positions after setting a threshold, and manually adjust unmarked peaks.
Spectral retrieval: Connect standard libraries (such as HR Aldrich FT-IR Collection) and compare the retrieval results.
quantitative analysis
Quantify using peak area or peak height method combined with standard curve.
Data export
Save the spectrogram in TIFF/CSV format with naming conventions (such as "sample name_date operator").
6、 Shutdown and maintenance
Shutdown procedure
Exit the software and turn off the power of the instrument host.
Remove the sample, clean the sample room, and place a desiccant to prevent moisture.
Turn off the computer and record usage.
routine maintenance
Clean the sample room after each use to prevent contamination.
Regularly calibrate the detector (such as once a month) to ensure data accuracy.
Keep the humidity in the instrument room below 70%, free from dust and corrosive gases.
7、 Precautions
safe operation
Wear protective goggles to avoid laser damage.
Water containing samples should not come into direct contact with KBr/NaCl window plates to prevent crystal failure.
Sample preparation requirements
The tablet should be free of cracks and have uniform light transmission. Local whitening indicates uneven thickness.
The solution method requires confirmation that the solvent does not absorb within the wavenumber range.
Fault handling
Check the power supply voltage, detector status, and optical path alignment when the signal is abnormal.
When the spectral noise is high, increase the number of scans or use digital filtering (such as median filtering).