ATR-FTIR
Definition
Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy: a non-destructive mid-infrared method that analyses a single drop of milk pressed against an ATR crystal. With chemometric calibration, a single scan quantifies fat, protein, lactose, total solids, and multiple adulterants simultaneously.
- Penetration depth
- 0.5 to 2 micrometers into the sample
- Crystal materials used
- Diamond, zinc selenide (ZnSe), or germanium (Ge)
- Sample preparation
- No preparation required; press directly onto crystal
- Spectral type
- Mid-infrared, near-surface analysis
Common questions
What makes ATR-FTIR different from regular FTIR?+
ATR-FTIR uses attenuated total reflectance, where a sample is pressed directly onto a high refractive index crystal like diamond or zinc selenide. An evanescent wave penetrates only 0.5 to 2 micrometers into the sample, giving you a near-surface infrared spectrum with no sample preparation needed.
Why is ATR-FTIR useful for analyzing milk or dairy products?+
The method is non-destructive and works on tiny samples. A single drop of milk pressed against an ATR crystal can reveal fat, protein, lactose, total solids, and adulterants all at once, making it ideal for quality control and detecting contaminants like melamine.
What samples can you analyze with ATR-FTIR?+
ATR-FTIR works best on samples you can press directly onto the crystal surface. The shallow penetration depth (under 2 micrometers) means it captures the near-surface chemistry, making it especially useful for liquids, pastes, and thin solids that don't require grinding or dissolving.
Related terms
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Explained in these topics
- Infrared Spectroscopy: FTIR and ATR-FTIRAttenuated total reflectance FTIR. The sample is pressed onto a high refractive index crystal (diamond, ZnSe or Ge); an evanescent wave penetrates 0.5 to 2 µm...
- Milk and Dairy Adulteration: Melamine, Urea, Detergent and the 2008 China ScandalAttenuated Total Reflectance Fourier-Transform Infrared Spectroscopy: a non-destructive mid-infrared method that analyses a single drop of milk pressed against...