The Use of ATR-FTIR Spectroscopy for Quantification of Adsorbed Compounds

Quantification of adsorbed amounts requires in most cases several assumptions. Adsorption of organic compounds, for example, is usually measured indirectly, by mass balance calculations based on the evaluation of the remaining chemical in solution. Such procedure might yield overestimates when precipitation or degradation of the adsorbate occurs and underestimates when separation of the sorbent material (e.g., clay particles) with the adsorbed chemical is not effective. This study presents a simple quantification procedure based on the ratio between IR absorption bands of the sorbate and the adsorbate. The advantages of the procedure are (a) direct evaluation of the adsorbed amount and (b) accurate measurement of chemicals that are hard to quantify, as those that do not absorb light in the UV-Visible range, or require expensive chromatography procedures

The Use of ATR-FTIR Spectroscopy for Quantification of Adsorbed Compounds

Quantification of adsorbed amounts requires in most cases several assumptions. Adsorption of organic compounds, for example, is usually measured indirectly, by mass balance calculations based on the evaluation of the remaining chemical in solution. Such procedure might yield overestimates when precipitation or degradation of the adsorbate occurs and underestimates when separation of the sorbent material (e.g., clay particles) with the adsorbed chemical is not effective. This study presents a simple quantification procedure based on the ratio between IR absorption bands of the sorbate and the adsorbate. The advantages of the procedure are (a) direct evaluation of the adsorbed amount and (b) accurate measurement of chemicals that are hard to quantify, as those that do not absorb light in the UV-Visible range, or require expensive chromatography procedures

The use of ATR-FTIR spectroscopy for quantification of adsorbed compounds

Quantification of adsorbed amounts requires in most cases several assumptions. Adsorption of organic compounds, for example, is usually measured indirectly, by mass balance calculations based on the evaluation of the remaining chemical in solution. Such procedure might yield overestimates when precipitation or degradation of the adsorbate occurs and underestimates when separation of the sorbent material (e.g., clay particles) with the adsorbed chemical is not effective. This study presents a simple quantification procedure based on the ratio between IR absorption bands of the sorbate and the adsorbate. The advantages of the procedure are (a) direct evaluation of the adsorbed amount and (b) accurate measurement of chemicals that are hard to quantify, as those that do not absorb light in the UV-Visible range, or require expensive chromatography procedures.Bernd Wicklein thanks Comunidad de Madrid for financial support through Personal Investigador de Apoyo contract and E. Ruiz-Hitzky (ICMM-CSIC) for supporting this work through a CICYT project (Spain; MAT2009-09960)

ATR-FTIR use for quantification of adsorbed organic compounds

Conference paper presented at ISRANALYTICA 2013 Conference and Exhibition, the 16th Annual Meeting of the Israel Analytical Chemistry Society, which took place in David Intercontinental Hotel (Tel-Aviv, Israel) during 30-31th January 2013. The paper was presented at first day in Session E: Spectral Methods of Analysis.Adsorption of organic compounds to clays is usually measured indirectly, by mass balance calculations based on the evaluation of the remaining chemical in solution. Such procedure might yield overestimates when precipitation or degradation occurs, and underestimates when separation between the sorbent particles and adsorbed chemical is not effective. This study presents a simple quantification procedure based on the ratio between IR absorption bands of the sorbent and the adsorbate. As an example, Fig. 1 shows FTIR spectra of phosphatidyl choline adsorbed on Wyoming montmorillonite. Adsorbed amounts (in mmole/g) were measured by TOC. Fig. 2 shows adsorbed amounts by TOC compared with the proposed technique. The advantages of the procedure are (a) it evaluates directly the adsorbed amount on the sorbent (b) it might measure accurately chemicals that don't absorb in the UV-Visible range