LimsPulse
Spectroscopy

Fourier Transform Infrared (FTIR) Spectrometer

Records the infrared absorption spectrum of a sample, which acts as a molecular fingerprint. The standard technique for identification of APIs and excipients in pharma QC.

  • Pharmaceutical
  • Polymers & plastics
  • Chemicals
  • Forensics
  • Food
  • Academic research
Photo of a Fourier Transform Infrared (FTIR) Spectrometer
Photo: Wang, F., Zhang, L., Zhang, X., Li, H. and Wu, S., CC BY 4.0 (cropped), via Wikimedia Commons
Follow your site SOP
This is a typical operating sequence for learning. Your instrument model and approved SOP take precedence.
STAGE 1

Before you start

  1. 1Check the calibration status, the humidity indicator (desiccant colour) and the logbook.
  2. 2Choose the technique the specification requires (ATR, KBr disc, film, or liquid cell) and use the same technique for sample and reference.
  3. 3For KBr, dry the KBr powder as per the SOP and keep it in a desiccator.
  • Never clean KBr windows or KBr beam splitters with water; they dissolve.
STAGE 2

Start-up

  1. 1Switch on and let the source and detector stabilise (commonly 30 minutes or more, or leave on standby as the manufacturer advises).
  2. 2Run the instrument's diagnostic or performance check if required (e.g. polystyrene check).
  3. 3Set the method parameters: range (e.g. 4000–400 or 4000–650 cm⁻¹ for diamond ATR), resolution (e.g. 4 cm⁻¹) and number of scans (e.g. 16–32).
  4. 4Clean the ATR crystal and collect a background spectrum.
  • Collect a fresh background regularly; changes in room humidity and CO₂ show up as false bands near 3700–3500, 1600 and 2350 cm⁻¹.
STAGE 3

Measuring samples

  1. 1ATR: place a small amount of sample to cover the crystal, apply the pressure clamp to the set position and collect the spectrum.
  2. 2KBr: grind about 1–2 mg of sample with about 200–300 mg of dry KBr, press into a clear disc and place it in the holder.
  3. 3Check the spectrum quality: strongest band not flat-topped, flat baseline, no large water or CO₂ bands.
  4. 4Measure the reference standard the same way (or use the approved reference spectrum) and compare.
  5. 5Clean the crystal between samples with a suitable solvent (e.g. isopropanol) and a soft tissue.
  • Do not use excessive pressure or hard, abrasive samples on ZnSe or Ge crystals; they scratch easily. Diamond is more robust.
STAGE 4

Shutdown

  1. 1Clean the ATR crystal and the sample compartment.
  2. 2Leave the instrument on standby or switch off as per the SOP; keep the compartment closed so the optics stay dry.
  3. 3Clean the KBr die and store it dry; complete the usage log.
In LimsPulse · Calibration Management

Keep every FTIR in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how