Near-infrared Raman instrument for rapid and quantitative measurements of clinically important analytes

We present the use of a near-infrared (IR) laser Raman spectroscopy instrum ent to measure the concentrations of many important analytes at their clini cally relevant levels in the simulated human serum. The Raman signal is gen erated by a 745 nm diode laser in a disposable waveguide capillary cell tha t contains a submicroliter sample. The Raman spectrum is acquired from the sample in 10 s. The major error in quantitative Raman spectroscopy caused b y the variation in laser power, optical alignment, and capillary cell size from measurement to measurement is eliminated by normalizing the spectrum t o the dominant water peak at 3350 cm(-1). Concentrations of glucose, acetam inophen, albumin, and other analytes are predicted using partial least squa res (PLS) calibration. An effective multiple bandpass-filtering method was developed to enhance the signal of the desired analytes to interfering back ground ratio for improvement of PLS calibration accuracy. It is demonstrate d that the accuracy of predicted concentrations for all analytes in the sim ulated human serum samples are highly acceptable for clinical diagnosis. Th e results promise the potential applications of the near-IR Raman instrumen t in medical practice. (C) 2001 American Institute of Physics.