Analysis and characterization of consumer products by FTIR, Raman, chemometrics, and two dimensional ATR-FTIR correlation spectroscopy.

摘要

My research focused on two projects using Fourier Transform Infrared (FTIR), Micro-Raman spectroscopy, Chemometrics (Principle Component Analysis, PCA), and two-dimensional (2D) ATR-FTIR correlation spectroscopic techniques.;Project one involves method development and validation for the simultaneous determination of dimethicone and cyclomethicone in skin protectant ointments by FTIR. A unique FTIR method that utilizes two absorbance bands (1260 cm -1 and 808 cm-1) to determine the concentrations of dimethicone and cyclomethicone using two simultaneous equations was first time developed. The absorbances at two fixed wave numbers 1258.50 cm -1 and 800.00 cm-1 were used to calculate the concentrations of dimethicone and cyclomethicone. A series of comprehensive method validation experiments were designed and carried out. The simultaneous equation approach employed in the method was shown to be linear, accurate, precise, and specific.;Project two is to characterize fish oil supplements using ATR-FTIR, Micro-Raman, Principle Components Analysis, and 2D ATR-FTIR Correlation Spectroscopy. Most of the fish oil supplements claim active ingredient EPA and DHA on the labels, but the actual chemical forms (ethyl ester or triglyceride) are not indicated. A fast qualitative ATR-FTIR method was developed to distinguish between the ethyl ester and the triglyceride forms of fatty acids using the carbonyl band position. Chemometrics approach - Principal Component Analysis (PCA) was used to classify fish oil supplements successfully by grouping the FTIR and Raman spectra. PCA was also demonstrated as a powerful tool to screen fish oil supplements and identify the products that may be made by the same manufacturers with the same quality, but sold with different prices. A fish oil FTIR spectral library was also created for rapid searching and product comparison. In addition, an ATR-FTIR standard addition method was evaluated for quantitative analysis of active ingredients EPA and DHA esters in fish oil products. Lastly, two-dimensional FTIR correlation spectroscopy was first time used as a new technique to study temperature dependent spectral characteristics of fatty acids such as EPA and DHA esters to provide further spectral information of these polyunsaturated omega-3 fatty acids.