Multianalyte Serum Assays from Mid-IR Spectra of Dry Films on Glass Slides

Abstract

An analytical method based upon mid-infrared spectroscopy is proposed, and the advantages of this approach are discussed. The method involves drying a liquid specimen to a film, and deriving analyte levels from the infrared spectrum of that film. The specific aim of this study was to determine whether glass might serve as a suitable substrate for the simultaneous determination of several analytes in complex mixtures. Using human serum as a “proof-of-concept” example, we show here that six commonly measured analytes may be determined from spectra originally measured by employing barium fluoride substrates, but restricting the analytical models to absorptions within the region 2000–4000 cm−1—i.e., making use of only those absorptions that are accessible with glass substrates. With the use of partial least-squares calibration models, it is shown that albumin, cholesterol, glucose, total protein, triglycerides, and urea may be determined with standard errors that approach or meet the criteria required for routine clinical analysis. The practical advantages of such an approach are discussed.