FTIR spectroscopy is an essential technique for the identification and characterization of materials, offering rapid, reliable, and non-destructive analysis. Used in diverse sectors such as chemicals, pharmaceuticals, food processing , and environmental and safety applications , it enables the detection of impurities, the identification of polymers, and the precise analysis of molecular structures.
YesWeLab makes available its expertise and network of partner laboratories to offer FTIR analyses tailored to the needs of manufacturers.
Table of Contents
Introduction
General overview of FTIR spectroscopy
FTIR (Fourier Transform Infrared) spectroscopy is an advanced analytical technique used to characterize the chemical composition of materials by measuring the absorption of infrared light by molecules. Each chemical bond absorbs energy at specific wavelengths, generating a unique spectrum, comparable to a molecular fingerprint. This technique is known for its speed, sensitivity, and non-destructive nature, making it an essential tool in laboratory analysis and materials quality control.
Importance and applications of FTIR spectroscopy
FTIR spectroscopy is widely used to identify the components of complex mixtures, detect impurities at low concentrations, and analyze the molecular structure of various materials. For example, in the food industry, it is used to authenticate essential oils, detect food fraud such as the adulteration of honey or vegetable oils, and monitor the presence of contaminants such as plasticizers or pesticide residues. In the environmental field, FTIR spectroscopy is used to analyze the chemical composition of microplastics in water or air, as well as to identify organic pollutants in soils. Finally, in materials science, it enables the characterization of polymers and the monitoring of plastic aging, thus contributing to the development of higher-performing and more sustainable materials. Its integration into rigorous standards such as ISO 17025 and COFRAC accreditations guarantees reliable and reproducible analyses, essential for meeting regulatory requirements and ensuring product quality.
Context and fundamental principles of FTIR spectroscopy
Origin and development of FTIR spectroscopy
Fourier transform infrared spectroscopy, commonly known as FTIR, emerged in the late 20th century, a time when technological advances in instrumentation significantly improved the accuracy of spectroscopic analyses. Its development is directly linked to the emergence of the Fourier transform concept, a mathematical tool created by the mathematician Jean-Baptiste Joseph Fourier in the 19th century. This concept allows a complex signal to be decomposed into a sum of sinusoids, thus facilitating the extraction of information about the different wavelengths of infrared light absorbed by a sample. Today, this approach enables scientists to verify the chemical composition of materials by measuring differences in absorbance at various wavelengths.
The first applications of FTIR occurred in the 1970s, when the first spectrometers capable of measuring infrared signals were equipped with Fourier transform technology, resulting in a significant reduction in measurement time and an increase in the accuracy of results. Since then, FTIR has become an indispensable tool in various industrial and scientific fields, such as chemistry, pharmaceuticals, food processing, and optics, among others.
Operating principle of FTIR spectroscopy
Explanation of the principle of infrared absorption
The fundamental principle of FTIR spectroscopy relies on the absorption of light by a sample when exposed to a beam of infrared radiation. Infrared energy is absorbed by the chemical bonds of the sample's molecules, according to the specific vibrational frequency of each type of chemical bond. These vibrations depend on various factors, such as the nature of the bonded atoms and the strength of the bond. Thus, each functional group exhibits a unique absorption band in the infrared range, creating a characteristic signature of the sample – this signature is what is observed in an FTIR spectrum.
Description of the Fourier transform process
One of the major innovations of FTIR spectroscopy is the use of the Fourier transform, a mathematical method that transforms a complex raw signal into a spectrum usable by scientists. Unlike conventional spectroscopies, which measure intensity at only one frequency at a time, FTIR spectroscopy allows for the simultaneous measurement of all frequencies using an interferometric device. The data obtained in the form of interference patterns are then processed by a Fourier transform algorithm to obtain a spectrum that absorbs light at different wavelengths. This spectrum is then interpreted to identify the functional groups and molecular structures of the sample.
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Sampling techniques and accessories
Sampling methods
Sample preparation is a crucial step in FTIR analysis. The ATR technique, for example, relies on the use of a crystal such as ZNSE, GE, or diamond, which generates an evanescent wave in direct contact with the sample. This method offers the advantage of performing measurements on liquid, paste, or film samples without requiring dilution in a matrix, thus avoiding saturation of absorption peaks. For solid samples, the kbr pellet method is commonly used. This involves grinding the sample into a fine powder and then mixing it with kbr to form a transparent pellet that allows the transmission of infrared light. Other supports, such as ZNSE, are also used to optimize contact between the infrared beam and the sample, thus ensuring high-quality analysis.
Importance of sample preparation
Proper sample preparation is essential to ensure the reliability of FTIR results. Depending on the nature and condition of the sample, different techniques can be employed. For example, in the case of multilayer or insoluble materials, the use of ATR accessories overcomes the difficulties associated with sample homogenization. Furthermore, careful preparation minimizes interference from water or contaminants, thus ensuring that the absorption spectrum accurately reflects the molecular composition of the analyzed material.
Advantages of non-destructive techniques
The sampling methods used in FTIR spectroscopy offer the major advantage of being non-destructive. Each analysis preserves the integrity of the sample, thus allowing for complementary or repeated tests on the same material. These techniques also require very small sample quantities, which is particularly advantageous when dealing with rare or precious materials. The non-destructive nature and low sample volume requirements give FTIR unparalleled flexibility in the field of laboratory analysis.
Normative references and accreditations
FTIR analyses are often performed in accredited laboratories that adhere to strict international standards, such as ISO 17025 and COFRAC requirements. These certifications guarantee the quality, accuracy, and traceability of the analytical results. The use of standardized equipment and the implementation of rigorous preparation protocols ensure optimal reproducibility of measurements. Compliance with these standards allows manufacturers and researchers to rely on reliable data for material characterization, quality control, and the optimization of production processes.
Industrial and research applications
Applications in materials quality control
FTIR spectroscopy is an indispensable tool for quality control in many industrial sectors. In the polymer industry, it enables the precise identification of material composition by detecting the presence of additives, contaminants, and impurities at very low concentrations. In the pharmaceutical field, the technique is used to analyze excipients and active ingredients, thus ensuring that formulations comply with strict regulatory standards. Similarly, in the cosmetics industry, FTIR plays a crucial role in validating the quality of raw materials and monitoring the stability of finished products, thereby contributing to the safety and efficacy of marketed products.
Use in research and development
FTIR spectroscopy also plays a major role in research and development. Researchers rely on this technique to explore the molecular structure of new materials and to study chemical interactions within complex mixtures. The ability to perform real-time measurements makes it possible to monitor the kinetics of chemical reactions, thus providing a thorough understanding of the transformation mechanisms. This capacity to rapidly analyze molecular changes is particularly useful for optimizing synthesis conditions, improving reaction yields, and developing innovative materials in fields such as nanotechnology, advanced composites, and biomedicine.
Integration with other analytical techniques
Integrating FTIR spectroscopy with other analytical techniques enhances the accuracy and completeness of materials analysis. For example, combining it with chromatography allows for the separation of different components in a mixture before their individual analysis by FTIR. Furthermore, combining it with Raman spectroscopy offers a complementary approach for studying molecular vibrations, which is particularly beneficial for the analysis of polymers and composite materials. These synergies between analytical methods provide comprehensive sample characterization, enabling laboratories to obtain more reliable results and confirm the hypotheses formulated during the development of analytical protocols.
Concrete examples of applications
Several use cases illustrate the effectiveness of FTIR spectroscopy in various industrial sectors and research. In the food industry, for example, FTIR is used to verify ingredient composition, detect the presence of allergens, and identify contaminants, thus ensuring the safety and quality of food products. In the automotive industry, it enables quality control of composites used to manufacture lightweight parts, ensuring their strength and durability. The technique also finds applications in the analysis of deposits and contaminants on surfaces, where it helps identify traces of undesirable substances that could compromise a product's performance. In the environmental field, FTIR is implemented to monitor air pollution and analyze the impact of contaminants on ecosystems, thereby supporting efforts to preserve and manage natural resources.
The key applications are:
- Controlling the purity of raw materials and early detection of contaminants.
- Real-time analysis of chemical reactions to optimize manufacturing processes.
- Detailed characterization of composite and polymeric materials.
- Environmental monitoring and assessment of the impact of pollutants.
Advantages and limitations of FTIR spectroscopy
Benefits
- Fast and non-destructive analysis that saves time and resources.
- Minimum sample quantity required for analysis.
- High sensitivity and accuracy for compound identification.
- Easy integration with other analytical methods for more in-depth characterization.
Boundaries
- Difficulty in analyzing complex mixtures due to signal overlap.
- Sensitive to interference (e.g., presence of water absorbing infrared).
- Not well suited to inorganic compounds that do not exhibit detectable infrared vibrations.
| Criteria | FTIR | Raman Spectroscopy | UV-Visible Spectroscopy | IR chromatography (GC-IR, LC-IR) | Mass Spectrometry (MS) | Chromatography (GC, HPLC) |
| Principle | IR absorption | Raman scattering | UV-Visible Absorption | Separation + IR | Ionization & mass/charge measurement | Separation of components |
| Ideal for | Functional groups | Non-polar compounds | Quantification of colorants | complex mixtures | Exact molecular mass | Quantification |
| Water sensitivity | Forte | Weak | N / A | Depends on the technique | N / A | Depends on the mobile phase |
| Quantification | Possible but limited | Less precise | Very precise | Precise | Very precise | Very precise |
| Separation of compounds | No | No | No | Yes | Yes | Yes |
| Sample Types | Solids, liquids, gases | Solids, liquids | Liquids | Gases, liquids | Gases, liquids, solids | Liquids, gases |
| Applications | Quality control, polymers | Surfaces, colored materials | Molecule dosage | Chemical formulations | Identification & quantification | Environmental and pharmaceutical analysis |
Conclusion
FTIR spectroscopy is an essential technique for the chemical analysis of materials. Thanks to its speed, sensitivity, and versatility, it is widely used in various industrial and scientific sectors. However, to guarantee optimal results, mastering sampling techniques and spectral interpretation is crucial. Combining it with other analytical methods enhances its effectiveness and expands its range of applications.
YesWeLab offers FTIR analysis services tailored to the needs of industrial companies , covering a wide range of matrices such as polymers, food products, cosmetics, and composite materials. Through its network of partner laboratories, YesWeLab ensures analyses comply with current standards (ISO, ASTM) and provides expert support for interpreting results. Industrial companies can thus identify the chemical composition of their materials, detect contaminants, verify regulatory compliance, and ensure quality control of their products. By centralizing analysis requests via an intuitive digital platform, YesWeLab simplifies the process of accessing FTIR spectroscopy tests and guarantees fast and reliable results.
