To lay down a procedure for calibration of FTIR Spectrophotometer.
This procedure is applicable for the Calibration of FTIR spectrophotometer
- QC officer/ Executive : Responsible for carry out calibration and to review and check the results of calibration of the instrument.
- QC Head/ Manager : Responsible for accountability and effective implementation of the standard procedure for operation of instrument and to finally approve the report of calibration.
- Operate the instrument as per its standard operating procedure.
- Ensure that before performing the calibration instrument is clean.
- Use reference standard polystyrene film for calibration along with its certificate traceable to NIST(5) standrads
- Thickness of the polystyrene film is 38 µ (micron) or 0.038 mm.
- Polystyrene film used for calibration of FTIR because it shows absorption bands covers the complete range of IR region.
- Polystyrene film is made up of polymers of styrene and stable at any temperature and highly durable.
- Set the polystyrene film in a sample chamber of an instrument and set the instrument parameters as mentioned below :
Resolution : 2 cm-1
Measurement mode : % transmittance & ratio
No. of scans : 1 to 20
Scanning range : 4000 to 400 cm-1 or as per requirement.
- Verification of the wave number scale:The wave-number scale may be verified using a calibrated polystyrene film, which has transmission minima (absorption maxima) at the wave numbers (in cm–1) shown in below
Standard wave number ( cm-1) Tolerance
3060.0 ± 1.0 cm-1
2849.5 ± 1.0 cm-1
1942.9 ± 1.0 cm-1
1601.2 ± 1.0 cm-1
1583.0 ± 1.0 cm-1
1154.5 ± 1.0 cm-1
1028.3 ± 1.0 cm-1
- Control of resolution performance : Record the spectrum of a polystyrene film approximately 35 µm in thickness. The difference between the percentage transmittance at the transmission maximum A at 2870 cm-1 (3.48 µm) and that at the transmission minimum B at 2849.5 cm-1 (3.51 µm) must be greater than 18. The difference between the percentage transmittance at the transmission maximum C at 1589 cm-1 (6.29 µm) and that at the transmission minimum D at 1583 cm-1 (6.32 µm) must be greater than 10.
- After calibration, affix the label” CALIBRATED” on the instrument.
- Frequency of calibration is quarterly.
- FTIR :Fourier transform Infrared
- QC: Quality Control
- NIST: National institute of standard and technology
- %: Percentage