Prediction of Sublayer Depth in Turbid Media Using Spatially Offset Raman Spectroscopy

• Published in: Analytical chemistry (Washington) Vol. 80; no. 21; pp. 8146 - 8152
• Main Authors: Macleod, N. A, Goodship, A, Parker, A. W, Matousek, P
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-11-2008
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Feasibility; Multivariate analysis; Nephelometry and Turbidimetry - instrumentation; Nephelometry and Turbidimetry - methods; Spectrometric and optical methods; Spectrum analysis; Spectrum Analysis, Raman - instrumentation; Spectrum Analysis, Raman - methods; Accuracy; Factor analysis; Turbidity; Feasibility; Raman spectrometry; Two dimensional analysis; Multivariate analysis; Monitoring
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac801219a

We demonstrate experimentally the feasibility of monitoring the depth of optically thick layers within turbid media using spatially offset Raman spectroscopy (SORS) in combination with multivariate analysis. The method uses the deep penetration capability of SORS to characterize significantly thicker (by at least a factor of 2) layers than possible with conventional Raman spectroscopy. Typical relative accuracies were between 5 and 10%. The incorporation of depth information into a SORS experiment as an additional dimension allows pure spectra of each individual layer to be resolved using three-dimensional multivariate techniques (parallel factor analysis, PARAFAC) to accuracies comparable with the results of a two-dimensional analysis.