The Basics of FTIR Spectroscopy: An Industry Guide / Innovatech

Fourier-Transform Infrared Spectroscopy, or FTIR analysis, is one of the most widely-used and reliable material analysis and quality control testing procedures used across industrial settings today – and for good reason. This is everything you need to know about FTIR spectroscopy: How it works, what it’s used for, and whether it’s right for your specific application.

What is FTIR Spectroscopy?

FTIR Spectroscopy is a type of absorption spectroscopy, which is the practice of shining different spectra of light radiation onto a sample of material in order to observe and record how that material absorbs and emits that radiation in response.

The name “Fourier-Transform” refers to a mathematical process that is used after the sample is exposed to light radiation in order to convert the data collected by the spectroscopy device into a usable form. This information is then used to identify the substance.

How does FTIR Spectroscopy Work?

Like other absorption spectroscopy, FTIR spectroscopy directs a beam containing several wavelengths of infrared light onto a sample. Bonds between elements within the sample absorb these different wavelengths at different frequencies in unique combinations.

FTIR spectroscopy differs from other forms of conventional absorption spectroscopy because those forms of spectroscopy use “dispersive spectroscopy,” which shines one “monochromatic” beam of light through the sample at a time and measures the absorption of each type of light separately. FTIR, on the other hand, uses a light that contains all infrared spectrums in one.

The light is shone through a configuration of mirrors known as a Michelson interferometer before it reaches the sample. This device is connected to a motor within the FTIR device, which spins it very quickly. Each mirror attached to the Michelson interferometer blocks a different spectrum of light within the broadband beam, rapidly altering the frequencies, or types, and combinations of wavelengths of light that contact the sample. This produces a great deal of raw data called an “interferogram” about how the sample absorbs each wavelength and combination of wavelengths in a very short period of time.

After the interferogram is generated, the FTIR device’s computer uses the Fourier transform algorithm to convert the data on the substance’s absorption of light at each mirror position into a map of the substance’s absorption of each wavelength of light over time of exposure. This map appears as a spectrum graph, which is then compared to huge reference libraries of infrared spectra. When the sample’s spectrum graph matches one of these reference graphs, it allows the FTIR experts conducting the test to positively identify the sample.

What Industrial Applications Does FTIR Spectroscopy Have?

FTIR spectroscopy has a large range of industrial applications across industries. These are just a few of the tasks it is most commonly used for:

Material and compound identification: By comparing a sample’s spectrum graph to reference graphs, it’s possible to identify the organic materials a compound sample consists of individually, as well as to understand how much of each material the sample contains.

Property identification: FTIR can also be used to allow experts to understand how materials are affected by various applications and environments, allowing them to understand the sample’s properties in action and therefore evaluate and determine the material’s proper usage.

- Quality control: By evaluating the materials of a sample, FTIR can help experts determine whether a product will perform to the necessary standards during its intended use, making FTIR a very useful quality control test.

Additive identification: By separately identifying each substance in a compound sample, FTIR can determine whether an additive has been added to a compound, as well as to identify the specific additives and understand how they will affect product performance.

Failure analysis: By determining what a substance is composed of and/or what got into a substance during operation, FTIR spectroscopy can often be used to determine why a product failed and, by extension, why the failure happened.

Contaminant analysis: One of the main ways FTIR is used for failure analysis is by analyzing contaminants that seep into samples. FTIR can usually determine what these contaminants are and how they affected the performance of the sample, often explaining the cause of failure.

Coating or film analysis: Because FTIR is so useful for separating out components of a compound sample, it can also be used to identify very thin films or coatings left behind on samples after their usage. This analysis can be used to determine what the film or coating is composed of, where it came from, and how it may affect the sample.

What Industries Use FTIR Spectroscopy?

Manufacturing – for material testing, additive analysis, quality control, process improvement, failure analysis, and more

- Pharmaceutical – for research and development, quality control, and more
- Polymer and plastic manufacturing – for plastic product quality testing, identifying additives in polymers, and analyzing surface contaminants

Surfaces and coatings – to ensure cleanliness and proper application of pretreatments and coatings

Forensics – for material and contaminant identification

Environmental analysis – By using FTIR to analyze samples taken from an environment, it’s possible to characterize what substances those samples are exposed to

Food manufacturing – For quality control, process control and improvement, material testing, additive analysis, and more

Oil and gas – For quality control, additive analysis, environmental analysis, and more

What Are the Advantages and Disadvantages of Using FTIR Spectroscopy for Industrial Applications?

Advantages

- Very accurate identification of compounds: FTIR Spectroscopy can be used to identify the individual organic materials making up compound samples as small as 10 to 20 microns, and can even identify stray particles, residues, films, and fibers left behind on such small samples. Wavelength measurement is an absolute form of analysis, leaving little margin for error in identification.

Non-disruptive: The sample is generally not damaged or altered in any way during FTIR testing.

Fast: Innovatech’s experts can collect the required information from FTIR Spectroscopy in as little as 24 to 48 hours.

Broadly applicable for organic compounds: FTIR can analyze virtually any organic compound with a high degree of accuracy, making it a highly useful catch-all “first step” for material identification.

Disadvantages

Often insufficient for inorganic compound identification: Unlike organic compounds, inorganic compounds can contain combinations of materials that are difficult to positively separately identify using FTIR alone. This makes FTIR a good first step for analyzing such inorganic samples, but additional testing is frequently required.

Slight possibility of test failure: FTIR analysis subjects the sample to all mid-infrared frequencies at once, which means if “noise” or interference occurs in one part of the radiation, it will spread throughout the spectrum and may provide inaccurate test results.

Less effective at trace identification: FTIR spectrometry is a bulk analysis methodology, which means it’s most effective at finding broad categories of substances within a compound, not necessarily identifying trace amounts of materials in mixtures.

When Should My Industry Use FTIR Spectroscopy?

FTIR spectroscopy is most likely to help you if:

You need to identify unknown materials in solid, liquid, or gaseous form
You need to identify all the categories of material in an organic compound
You want to identify and, in some cases, quantify, a surface contamination present on a material
You want to identify what a contaminant is made of in order to understand where it may have come from
You want to identify any additives placed in a polymer, oil, or other compound
You need to confirm whether specific substances are in a product sample and characterize how those substances make that product behave and function
You need to understand why an organic product failed to function the way it should and/or why the product is deteriorating as a result of use

How Can I Access FTIR Spectroscopy?

FTIR spectroscopy is useful for virtually any industry that needs to identify and characterize materials within a compound sample. If you think FTIR Spectroscopy is right for your industrial needs, get in touch with the experts at Innovatech right away.