FT-IR can be used quantitatively to determine the concentration of components, but the accuracy depends on good sample preparation, selecting the appropriate absorption bands, and proper calibration with standards.

Baseline correction is usually necessary to improve accuracy, especially if there is drift or offset in the baseline that could affect measuring peak height or area. Baseline correction can be applied over the entire spectrum (commonly 4000 to 600 cm⁻¹) or segment-wise, depending on how stable the baseline is and the nature of the peaks.

Regarding whether to use peak height or area under the curve for quantification, the area under the peak is generally more reliable because it accounts for the entire absorption band, reducing the impact of noise and signal fluctuations.

I recommend testing both methods using calibration samples with known concentrations to see which gives better precision and reproducibility in your specific case.

FT-IR as a Quantitative Tool: Yes, FT-IR can be used quantitatively, but it requires careful baseline correction, peak selection, and calibration. It’s reliable when properly validated.

Spectra Quality: If the graph lines are merged, it's hard to analyze. In Origin, use “Stack” by Y Offsets to separate the spectra for clarity.

Baseline Correction: Baseline should be corrected locally, around each peak of interest—not across the full range (4000–600 cm⁻¹). Check that baselines are flat near the chosen peaks.

Band Height vs. Area: Area under the peak is generally more accurate and less sensitive to noise or resolution differences than peak height. Use area for quantitative analysis when possible.