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FTIR Spectroscopy is an analytical technique used to identify organic, polymeric, and, in some cases, inorganic materials. The FTIR analysis method uses infrared light to scan testsamples and observe chemical properties. When trying to identify an unknown material, FTIR (Fourier Transform Infrared Spectroscopy) analysis is a great tool to answer, “What is it?”. It works well for solids, liquids and gases, and can be applied to pure substances or mixtures. Quantitative or qualitative analysis is available. FTIR is not the best technique to measure trace contaminants, but functions extremely well identifying bulk materials. 

Are you trying to determine material composition, identify impurities, or track changes in your raw materials or finished product? FTIR can provide quality control for your manufacturing process. FTIR analysis also has regulatory compliance applications, such as Respirable silica (NIOSH 7602), for industrial hygiene at construction and petroleum fracking sites. 
Fourier Transform Infrared Spectroscopy (or FTIR for short) identifies chemical bonds in materials via their infrared absorption spectrum. Transmission and Attenuated Total Reflectance (ATR) modes permit analysis of a wide range of solids, powders, non-aqueous liquids and gases. 
The FTIR spectrum is the “infrared fingerprint” of the material. Qualitatively, unknowns can be identified by comparison with an extensive library of FTIR spectra. Our reference sample database includes tens of thousands of spectra for comparison purposes. Quantitatively, FTIR-ATR Analysis is often the first step in the materials analysis process due to its speed and simplicity. 
Samples weighing as little as 50 milligrams can be evaluated using FTIR-ATR analysis. The small sample size allows for selective identification of particles, residues, films or fibers.

Applications of FTIR Transmission & ATR Analysis:

• Quantitative Scans
• Qualitative Scans
• Solids
• Non-Aqueous Liquids
• Organic Samples
• Inorganic Samples
• Unknowns Identification
• Impurities Screening – Routine QA/QC analysis with Accept/Reject limits
• Soil Pharmaceuticals
• Paints, Coatings
• Laminates
• Assessing purity – raw materials, intermediate materials, finished product
• Polymers, plastics – Identifying:
  • Base polymer composition
  • Additives
  • Organic contaminants
  • General type of material being analyzed when there are unknows
• Common Household Items
  • Cleansers and Detergents
  • Baking Powders and Ingredients
  • Paints
  • Oils
  • Paper
  • Medications
• Fibers
  • Synthetic Fibers (acrylic, nylon, polyester, rayon)
  • Natural Fibers (cotton, silk, wood)
• Adhesives
  • Glue
  • Epoxy
  • Resin
• Biodiesel Content in Diesel Fuel
  • Trace Level (0.025%) measurement for biodiesel averse applications
  • Gross composition

Qualitative Scans 

Qualitative scans can be used to rapidly assess unknown materials for identification and for rapid checks on impurities. In terms of process QC, high quality spectral scan of your reference material(s) can be generated and stored in our spectral library database and quickly compared to new materials in your manufacturing process and flag them as acceptable or unacceptable.

Quantitative Scans 

A wide variety of materials can be quantified using the FTIR-ATR materials characterization technique. Quantification requires that a standard calibration curve of known concentrations be created. This is how FTIR is used for the analysis of respirable silica using the NIOSH 7602 method or for determining low levels of Biodiesl in diesel fuel.

ATR-FTIR can be effectively used for quantitative analysis. Non-destructive measurement of samples is possible using ATR-FTIR. Prepare known concentrations of your samples and analyze. For this you must know the prominent IR peak in your sample. Measure  peak heights/areas and prepare a calibration curve. From this you can determine the concentration in unknown sample by noting peak height. It depends on what kind of material you are analyzing. If your material varies in composition as a function of time or temperature, the thickness of your sample may vary too (e.g. due to evaporation of solvent etc). In such case, you have to select a peak that remains constant (not shifting) during the entire process. In absorption mode, find out the area (not the height) of the main peak (of your interest) and divide with the area of the constant peak.

Below is our calibration for respirable alpha silica using NIST standards:

A few of the spectra used in this calibration (from NIST Standards) are shown below:

How do I find the area under my curve using origin?

Plot your data (if you have not already) and make the graph window active, you can either use Integration gadget or Peak Analyzer.

For Integration gadget, go to Gadgets:Integrate… and click OK in the coming up dialog to bring up the yellow Region of Interest (ROI) box. Drag to position and resize the box to the area you want to calculate, then the Area and FWHM information will show up on the ROI top.

For Peak Analyzer, follow the steps below:

1. Choose Analysis: Peaks and Baseline: Peak Analyzer.
2. In the first page (the Goal page), select the Integrate Peaks radio button in the Goal group.
3. For nominal data with positive and negative peaks, step through the four steps in the dialog window: Baseline Mode, Subtract Baseline, Find Peaks and Integrate Peaks.
4. The resulting plot will label each peak with the x-coordinates.
5. The workbook containing results output shows the calculated result parameters for each peak, including peak areas, in the Integration_Resultn worksheet. The data for the integral curve can be found in the Integrated_Curve_Datan worksheet.

How To Calculate Area Under A Plotted Curve In Excel?

For example, you have created a plotted curve as below screenshot shown. This method will split the area between the curve and x axis to multiple trapezoids, calculate the area of every trapezoid individually, and then sum up these areas.

1. The first trapezoid is between x=1 and x=2 under the curve as below screenshot shown. You can calculate its area easily with this formula:  =(C3+C4)/2*(B4-B3). 

2. Then you can drag the AutoFill handle of the formula cell down to calculate areas of other trapezoids.
Note: The last trapezoid is between x=14 and x=15 under the curve. Therefore, drag the AutoFill handle to the second to last cell as below screenshot shown.   

3. Now the areas of all trapezoids are figured out. Select a blank cell, type the formula =SUM(D3:D16) to get the total area under the plotted area.

 Calculate Area Under A Plotted Curve With Chart Trendline

This method will use the chart trendline to get an equation for the plotted curve, and then calculate area under the plotted curve with the definite integral of the equation.

1. Select the plotted chart, and click Design (or Chart Design) > Add Chart Element > Trendline > More Trendline Options. See screenshot:

2. In the Format Trendline pane:
(1) In the Trendline Options section, choose one option which is most matched with your curve;
(2) Check the Display Equation on chart option. 

3. Now the equation is added into the chart. Copy the equation into your worksheet, and then get the definite integral of the equation.

In my case, the equation general by trendline is y = 0.0219x^2 + 0.7604x + 5.1736, therefore its definite integral is F(x) = (0.0219/3)x^3 + (0.7604/2)x^2 + 5.1736x + c.

4. Now we plug in the x=1 and x=15 to the definite integral, and calculate the difference between both calculations results. The difference represents the area under the plotted curve. 
 

Area = F(15)-F(1)
Area =(0.0219/3)*15^3+(0.7604/2)*15^2+5.1736*15-(0.0219/3)*1^3-(0.7604/2)*1^2-5.1736*1
Area = 182.225

In OriginPro, the Peak Analyzer is capable of creating and subtracting baseline. There are various ways for baseline creation. You can generate baseline anchor points automatically or manually and then connect them with interpolation or fit them with a function.

Steps

Create baseline with 2nd Derivative method

1. Start a New Workbook and import the <Origin EXE Folder>\Samples\Spectroscopy\Baseline.dat. Highlight the second column. In the main menu, select Analysis: Peaks and Baseline: Peak Analyzerto open the dialog of the Peak Analyzer.
2. In the first page (the Goal page) of the Peak Analyzer, select Create Baseline as Goal. Click Next to go to the Baseline Mode page.
3. Next we are going to create an user defined baseline for this spectrum by defining anchor points. On the Baseline Mode page, select User defined from the Baseline Mode dropdown list. Check on Snap to Spectrum to make sure when you add or move a baseline anchor point, it will be pulled back onto the spectrum.
4. The first two methods in Anchor Points Finding are the most commonly used, and they can find anchor points automatically based on the derivative of the spectrum. If the baseline is approximately constant, 1st Derivative and 2nd Derivative is more powerful, otherwise, we should use 2nd Derivative. In this example, the baseline is more curly, so we use 2nd Derivative(zeros) method for locating anchor points.For other methods in Anchor Points Finding and related smoothing parameters, you can refer to the link: Baseline Mode Page.
5. Now click the Find button in the Baseline Anchor Points group. You can preview the anchor points in preview window.
6. Click Next to go to the Create Baseline page, select Interpolation in the Connect by drop-down list. In Interpolation method group, select Spline from the drop-down list. You can preview the spectrum in preview window, and then click Finish to get the baseline data.

Create baseline with ALS Method (Pro)

1. Start from the Baseline Mode page, and select the Asymmetric Least Squares Smoothing Baseline (ALS) as the baseline method. The ALS baseline can be tuned easily with a few parameters without pre-selecting any anchor points.
2. Click Next go to Asymmetric Least Squares Smoothing Baseline page, adjust the parameters to make the baseline optimal, then click Finish button to output the results table and graph.

Subtract Baseline from a Spectrum

1. If you want to subtract baseline, select Subtract Baseline as the Goal at start page.
2. After you created a baseline, click Next button to go to Subtract Baseline page.
3. Click Subtract button for previewing the subtracted data. The baseline data and subtracted spectrum will be outputted after clicking Finish button. The figures below displayed the Subtract Baselinepage and the preview of the subtracted spectrum.

Only 10 $ for interpretation of your FT-IR spectrum
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Send your spectra...

Fourier Transform Infrared Spectroscopy (FTIR) is one of the most widely used analytical techniques in materials science, chemistry, pharmaceuticals, polymers, nanotechnology, and environmental studies. While collecting an FTIR spectrum is straightforward, extracting reliable structural and chemical insights requires proper software.

In this guide, we introduce the most useful free, trial, and professional FTIR data-analysis tools available today—along with a note about Analyzetest.com, a professional service for accurate spectrum interpretation.

1. Protea Free FTIR Software

Website: protea.ltd.uk/free-ftir-software.html

Protea offers a fully free FTIR software package designed for spectral visualization, peak picking, baseline correction, and spectral library comparison. It is lightweight, beginner-friendly, and suitable for quick analysis of standard FTIR spectra in educational or research environments.

2. IRPal

Website: irpal.soft112.com

IRPal is a simple but effective tool for peak identification and functional group prediction. It is particularly useful for students or early researchers who need a fast interpretation of IR absorption bands based on standard chemical references.

3. OriginLab (Fully Functional Trial)

Website: originlab.com/demodownload.aspx

OriginLab is one of the most powerful scientific data-analysis platforms. With its fully functional trial version, users can perform:

• Advanced curve fitting
• Peak deconvolution
• Baseline subtraction
• 2D/3D plotting
• Customizable script-based analysis (LabTalk, Python)

For FTIR, OriginLab excels at Gaussian/Lorentzian peak fitting, especially when analyzing overlapping carbonyl, hydroxyl, or phosphate bands.

4. irAnalyze (30-Day Trial)

Website: labcognition.com/en/irAnalyze.html

irAnalyze provides sophisticated tools for:

• Spectral interpretation
• Band assignment
• Functional group identification
• Library search
• Chemometric processing

Its algorithms are optimized for polymer and organic chemistry applications.

5. VibSpec / IRIS (10-Day Free Access)

Website: vibspec.com/html/software_eng.html

VibSpec includes IRIS, an advanced interpretation tool based on vibrational spectroscopy theory. It is designed for researchers who want:

• Automatic interpretation suggestions
• Group frequency analysis
• Raman-IR combined interpretation
• A knowledge-based expert system

Although the free usage is limited to 10 days, the software is highly valuable for academic research.

6. ir-spectra (Free Demo)

Website: ir-spectra.com

ir-spectra is a user-friendly spectral viewer supporting:

• Baseline correction
• Peak assignment
• Library matching

Its simplicity makes it suitable for quick checks and undergraduate laboratories.

7. Gnuplotting (Free, Open Source)

Website: gnuplotting.org

Gnuplot is an open-source plotting engine widely used for scientific visualization. Although not an FTIR-specific tool, it provides:

• High-quality spectral plotting
• Curve fitting
• Batch processing
• Script-based automation

It is ideal for researchers who prefer command-line tools or need automated analysis pipelines.

8. QtiPlot

Website: qtiplot.com

QtiPlot is an affordable Origin-like software offering:

• Signal processing
• Spectral smoothing
• Peak fitting
• Customizable graphs

It is commonly used in universities as a low-cost alternative to OriginLab.

9. ACD/Spectrus Processor (30-Day Trial)

Website: acdlabs.com/software-solutions/acd-spectrus-processor/

Spectrus Processor is a professional-grade tool for handling FTIR, Raman, NMR, MS, and other spectroscopic data. Its FTIR capabilities include:

• Intelligent peak assignment
• Structure-spectrum correlation
• Spectral library management
• Multi-technique data integration

This is an excellent solution for industrial laboratories.

10. Bio-Rad Spectroscopy Software (Two-Week Trial)

Website: bio-rad.com/en-in/category/spectroscopy-software

Bio-Rad provides robust solutions for FTIR and Raman analysis, offering:

• KnowItAll spectral libraries
• Automatic band assignment
• Advanced data processing
• Chemometrics and PCA

Widely trusted in professional and industrial environments.

Need Expert FTIR Interpretation?

Software is powerful, but correct interpretation still requires expertise—especially when dealing with:

• Overlapping peaks
• Polymer composites
• Nanomaterials
• Organic/inorganic hybrid systems
• Plant-extract–based green synthesis
• Reaction mechanism analysis

If you need accurate, publication-ready FTIR analysis, you can use our professional service:

👉 Analyzetest.com — Expert Analysis for FTIR, XRD, SEM, EIS, and all Scientific Data

We provide:

• Peak assignment
• Functional group identification
• Comparison between raw materials, intermediates, and final products
• Quality-control validation
• Complete report preparation for theses, papers, and industrial R&D

Whether you’re a student, researcher, or industry professional, our team can help you transform your spectra into meaningful scientific insights.