Quantitative Analysis, Infrared

Abstract

In this article, after reviewing the different mathematical methods used in quantification we will describe and discuss their respective advantages and inconveniences. First of all, different examples of applications of infrared (IR) spectroscopy, used with or without other analytical chemistry methods, will be presented. Some examples of direct quantitative analysis in food analysis will be reviewed: lipids (measurement of unsaturation degrees, lipids determination), carbohydrates, proteins (secondary structures, quantitative analysis). We will also focus on original examples of the use of IR spectroscopy combined with enzymes. Secondly, some examples of Fourier transform infrared (FTIR) analysis coupled with other analytical methods are reviewed in the following fields: FTIR quantification in pharmaceuticals, petroleum, paints and other industrial products and in the fields of health, environment, and trace compounds analysis. Finally, we will discuss the limitations and perspectives of IR spectroscopy for quantitative analysis. It appears that the most significant developments in the field of quantitative analysis will most probably come through progress in chemometrics and flow analysis (FA) (automation).

Determination of extra virgin olive oil in quaternary mixture using FTIR spectroscopy and multivariate calibration

“…Meanwhile, the second derivative can eliminate the slope effect. However, derivation treatments can strongly affect the measurement sensitivity [4]. Note: The frequency regions and multivariate calibration chosen for quantification were marked with italic.…”

Development of a Univariate Membrane-Based Mid-Infrared Method for Protein Quantitation and Total Lipid Content Analysis of Biological Samples

“…The Amide I absorption consists predominantly of C=O stretching vibration (about 80%) with a minor contribution from the C–N stretching vibration (20%), while the Amide II band is more equally split between N–H bending (60%) and C–N stretching (40%) [ 30 ]. Until recently, analysis of the Amide I and II absorption regions has been severely hampered in aqueous samples due to spectral interference of a strong water absorption band at 1500–1700 cm −1 [ 25 ]. While the advent of ATR and flow-through cells has circumvented the water interference issues, their utility is limited due to practical drawbacks which include instrumentation cost, expertise, and time required for method development and accurate data analysis.…”

Application of FTIR spectroscopy coupled with chemometrics for authentication ofNigella sativaseed oil

“…The functional groups responsible for absorption of IR by the common edible fats and oils have been reported in our previous papers. These frequency regions were further optimized in order to quantify the level of GSO in NSO with the aid of multivariate calibration [4].…”

“…This is carried out by computing the coefficient of correlation (R 2 ) determining the peak absorbancies at selected frequency regions to the concentration of oils. FTIR spectral (frequency) regions contributed to the high correlation between the actual and FTIR predicted values (high R 2 ) were selected; meanwhile regions that reveal low R 2 should be ignored [4].…”