What are microplastics?
Microplastics are small bits of plastic, 5 millimeters or less, and either engineered for end-products, or the result of environmental degradation of polymer-based trash.
Researchers have found microplastics in marine and terrestrial life. It invades the food chain, and it’s even been found in salt, sugar, beer, alcohol, and honey. Not to mention glaciers and rainwater.
Raman Spectroscopy
- Based on the inelastic scattering of light (Raman scattering)
- Provides information about the vibrational modes of molecules based on changes in the frequency of scattered light, often focusing on the symmetry of bonds
- Uses a laser (visible, NIR, or UV) as the light source
- Does not require special sample preparation and particularly useful for aqueous samples since water has a low Raman scattering signal
- Works well on transparent materials because it is based on light scattering and ideal for analyzing materials that do not absorb infrared light
- Fluorescence can overwhelm the Raman signal, making it difficult to extract accurate data from fluorescent samples
- Often require more specialized equipment which can increase the overall cost and complexity
- Very sensitive to microplastic particles, even at low concentrations
FTIR Spectroscopy
- Based on the absorption of infrared light by a sample
- Provides information about the absorption of infrared light, specifically the frequencies at which a molecule absorbs, relating to the stretching and bending of bonds
- Uses a broad-spectrum infrared light source
- May sometimes require sample preparation and water can interfere with FTIR, as it strongly absorbs infrared light, making it more challenging to analyze aqueous samples
- Typically does not work well with transparent samples, as they can transmit infrared light, resulting in weak absorption signals
- Not typically affected by fluorescence, especially for samples that are naturally fluorescent
- Less expensive and simpler to operate
- Performance can be limited for very small particles and is generally more effective for larger particles
For comprehensive microplastic analysis, many researchers often use both techniques, combining their strengths for accurate and efficient identification of microplastic particles.
Raman spectroscopy is highly efficient for quick, non-destructive analysis of small, colored, and diverse microplastic particles, offering high spatial and spectral resolution. It is particularly useful in examining samples with weak FTIR absorption bands.
Watch our webinar “Microplastics characterization by Raman microscopy” to learn more about the role of Raman Spectroscopy in microplastics characterization.
To know more about HORIBA’s global efforts in microplastics research, you may visit https://horiba.com/microplastics.