QUANTIFICATION OF POLYDIMETHYLSILOXANE CONCENTRATION IN TURBID SAMPLES USING RAMAN-SPECTROSCOPY AND THE METHOD OF PARTIAL LEAST-SQUARES

This paper presents a preliminary application of Raman spectroscopy in conjunction with the chemometric method of partial least squares to p redict silicone concentrations in homogenous turbid samples. The chemo metric technique is applied to Raman spectra to develop an empirical, linear model relating sample spectra to polydimethylsiloxane (silicone ) concentration. This is done using a training set of samples having o ptical properties and known concentrations representative of those unk nown samples to be predicted. Partial least squares, performed via cro ss-validation, was able to predict silicone concentrations in good agr eement with true values. The detection limit obtained for this prelimi nary investigation is similar to that reported in the magnetic resonan ce spectroscopy literature. The data acquisition time for this Raman-b ased method is 200 s which compares favourably with the 17 h acquisiti on required for magnetic resonance spectroscopy to obtain a similar se nsitivity. The combination of Raman spectroscopy and chemometrics show s promise as a tool for quantification of silicone concentrations from turbid samples.