MID-FTIR-PLS Chemometric Analysis of Cr(VI) from Aqueous Solutions Using a Polymer Inclusion Membrane-Based Sensor

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Chromium(VI) is a toxic pollutant requiring sensitive detection methods.
• Polymer inclusion membranes (PIMs) offer selective extraction capabilities.
• Mid-Fourier transform infrared spectroscopy (MID-FTIR) provides molecular information.

Purpose of the Study:

• To develop a quantitative chemometric method for Cr(VI) detection using PIMs and MID-FTIR.
• To optimize and characterize the PIM-based extraction system for Cr(VI).
• To establish the analytical performance and reliability of the developed sensor.

Main Methods:

• Development of a partial least squares (PLS) quantitative method.
• Optimization of PIM composition, extraction time, and pH.
• Analysis of MID-FTIR spectra combined with principal component analysis (PCA) and iterative PLS (iPLS) for variable selection.
• Characterization of adsorption isotherms, distribution coefficients, and extraction efficiency.

Main Results:

• The system exhibited Langmuir-type adsorption with favorable metal uptake (K = 2199 cm³/mmol, q = 0.188 mmol/g).
• A 1:1 Cr(VI):Aliquat 336 extraction ratio was confirmed.
• The PLS model, utilizing iPLS-selected wavelengths, demonstrated excellent performance (R² Cal = 0.98145, R² CV = 0.940902).
• Key performance metrics include a limit of detection (LD) of 1.9 ppb and a linear range of 5.8-100 ppb.

Conclusions:

• A robust and sensitive PIM-based sensor for Cr(VI) detection was successfully developed.
• The method offers a simplified, efficient, and cost-effective alternative to existing techniques.
• The sensor is suitable for practical environmental monitoring applications due to its ease of implementation.