Chemometrics for Quantitative Determination of Terpenes Using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy: A Pedagogical Laboratory Exercise for Undergraduate Instrumental Analysis Students

Chemometric techniques such as partialleast-squares (PLS) regressionhave been applied with huge success to a wide array of chemical problemsincluding multicomponent analysis of analytes in complex mixtures.Despite this, there are few examples of laboratory pedagogical exercisesthat involve students in the acquisition of chemical data from infraredspectroscopic-based instrumentation, followed by quantitative chemometricanalysis using PLS. In this article, we present a computational activitythat introduces undergraduate students in an instrumental analysislaboratory setting to data acquisition using attenuated total reflectance-Fouriertransform infrared (ATR-FTIR) spectroscopy followed by data analysisusing PLS. The first part of the activity involved students creatingmixture designs of binary terpene components consisting of p-cymene and limonene. These mixtures were then analyzedusing an ATR-FTIR spectrometer, where students became familiarizedwith the instrument and were shown how to characterize and differentiatethe aforementioned terpenes using their generated FTIR spectra. Thesecond part of the activity involved preprocessing the acquired FTIRspectral data from the first part followed by the simultaneous quantitativedetermination of the prepared terpenes using PLS. On the basis ofstudent surveys, it can be concluded that this convenient and inexpensiveactivity was ultimately successful in introducing students to theuse of chemometrics for quantitative analysis of terpenes using anATR-FTIR. This easy-to-do two-week activity can be used as a standalonefor instrumental analysis laboratory classes and can even be integratedin advanced courses in applied spectroscopy and chemometrics.