Fourier transform infrared spectroscopy analysis, or “FTIR” analysis, is a type of organic material analysis with a broad range of applications. It’s particularly useful for certain types of oil analysis. Here’s why:
What is FTIR analysis?
Fourier transform infrared spectroscopy is a type of absorption spectroscopy that is used to identify the presence and composition of various organic and inorganic materials in solid, liquid, or gaseous compounds.
FTIR analysis is one of the most widely-used and reliable material quality control and identification testing procedures used today, because it is fast, accurate, and, most importantly, does not harm or alter sensitive compounds.
How does FTIR oil analysis work?
FTIR analysis shines infrared light radiation through an interferometer, which is a series of stationary and movable mirrors. Upon contacting these mirrors in specific combinations, the light is “encoded” into every relevant infrared frequency simultaneously.
Next, this newly encoded infrared spectrum passes through the oil sample. As it does so, the various molecular structures inside the sample will absorb specific frequencies of the radiation. As a result, the signal produced by the waveform of the infrared spectrum will be different from what it was before it entered the sample.
Every molecule absorbs different frequencies of infrared radiation at different, precise wavelengths. After the analyzing, the computer converts the spectrum into data via a mathematical process called “Fourier transformation,” the waveform can be measured in “wavenumbers” of reciprocal centimeters, or cm-1.
By comparing the waveform of the spectrum before and after it passes through the oil sample and looking for telltale readings of the waveform, analysts can determine the molecular contents of the sample.
For example, if an absorbance band is seen near 1630cm-1, that likely denotes the process of nitrogen oxide fixation within the oil sample. The materials that create this feature in oil are nitrate esters. Therefore, a reading of 16030cm-1 would suggest the presence of these esters.
When is FTIR used for oil analysis?
FTIR analysis is used for a wide variety of oil analysis, usually to identify possible contaminants or diluting agents in a used sample. Specific common applications include:
- Determining the presence and cause of oil degradation, whether by oxidation, nitration, sulfation, glycols, diesel and/or gasoline mixing, or additive use
- How oil changes when it is used (via testing an unused sample and then a used sample to identify differences between the two)
- Identifying any additives present in the oil
- Identifying water contents of oil
- Identifying soot particles in oil
Why is FTIR analysis particularly useful for oil analysis?
FTIR is a bulk analysis technique that allows for a high level of accuracy and detail relative to its time and resource cost. By using infrared spectroscopy, FTIR analysis can identify the major components of a mixture without the need to manually separate those components in the oil first. Oil separation can be difficult and can obfuscate testing results, so FTIR is quite useful in cases where the oil sample should not be altered by the testing in any way.
FTIR spectroscopy also provides an easy and intuitive way to determine what kind of changes an oil sample undergoes through use. First, an unused sample of oil is tested with FTIR analysis, and its molecular structure is recorded. Then, the used sample is tested. By subtracting the base oil and additive structure from the results of the used sample test, it’s possible to understand how using the oil alters its structure.
When should I use FTIR oil analysis?
FTIR oil analysis is a great fit if you’re looking to:
- Understand how using an oil product alters its composition
- Identify the chemical category of a type of pollutant in your oil
- Find out if your oil is diluted or degraded by reacting to nitrogen, sulfur, oxygen, etc.
- Find out if water and/or soot has entered the oil at any point during the production or storage process
- Prove composition for quality assurance
- Conduct failure analysis of underperforming oils
- Determine how and where pollutants entered your oil during the production or storage process
What are the drawbacks of FTIR oil analysis?
FTIR oil analysis can only locate the broad category of compounds or effects that alter its infrared spectrum’s wavelengths into certain wavenumbers—it can’t identify the specific compounds within those categories.
For example, the reading of 1630cm-1 in the example above would positively identify the presence of nitrous oxide fixation caused by nitrate esters in the oil sample, but it cannot identify the specific esters themselves.
This could be a problem for the organization testing the oil if, for example, there were multiple points in their production process where different kinds of nitrate esters could have entered the oil.
Testing used oil with FTIR oil analysis can also be an issue from a practical perspective. Though FTIR oil analysis is a great way to identify changes in oil as a result of use, in order to be accurate, FTIR analysis will require an unused sample to cross-check the used sample with.
This unused sample must be from not only the same type, brand, and grade as the used oil, but also from the same specific batch of oil manufactured. If all of the oil in a given batch has already been used, then FTIR oil analysis will not be as useful to find out how use affected it.
When shouldn’t I use FTIR analysis for oil analysis?
Because of the aforementioned drawbacks, FTIR probably isn’t suitable for your oil analysis if:
- You are trying to isolate and identify one very specific contaminant among multiple of the same category/effect
- You require comprehensive identification of all specific compounds within an oil
- You want to test the effect of an oil’s usage but you do not have access to a sample of unused oil from the batch you need to test
How can I get FTIR oil analysis?
If you think FTIR analysis may be the right fit for your oil analysis needs, get in touch with the experts at Innovatech. Our team can conduct fast and accurate FTIR analysis on your oil sample ASAP.