Quantitative determination of surface area of silica gel particles by near infrared spectroscopy and chemometrics

Surface areas of silica gel particles have been quantitatively determined by using near infrared spectrometry and chemometrics. Surface areas of six silica gel samples with varying surface area (300–750 m2/g) have been determined by the common Brunauer–Emmett–Teller (BET) method and used in preparing mixtures of silica gel samples with varying surface area in the ranges 300–474 and 500–750 m2/g. The near infrared spectra of the mixtures were measured and the spectral profiles calibrated against the calculated surface area of the mixtures as dependent variable using partial least squares (PLS) technique. The models obtained from the calibrations were then used in predicting the surface area of unknown silica gel samples. ror estimate in the surface area predicted for the unknown samples lie in the same range as the error limits in the BET surface area determination. The technique provides a fast, easy and inexpensive method for the determination of surface area of silica gel particles.