Determination of triglycerides in human plasma using near-infrared spectroscopy and multivariate calibration methods

The quantitative analysis of triglycerides in human blood plasma was studie d without previous sample pre-treatment using direct near-infrared spectros copy absorption measurements. A comparison of several multivariate calibrat ion techniques, such as partial least squares (PLS), multiple linear regres sion (MLR) with feature selection by a genetic algorithm, and a neural netw ork, was performed. Several pre-processing data techniques were tested and the best one was obtained using Fourier transform to reduce the random nois e, followed by water spectrum subtraction and the first derivative. Also, d ifferent spectral ranges were tested, and the range 5500-6870 cm(-1) was ch osen. The three calibration techniques presented similar performance with r elative errors around 9%. In this case, we choose the simplest calibration model which is MLR, because it is more easily implemented in routine practi ce. (C) 2001 Elsevier Science B.V. All rights reserved.