Micro-analysis by near-infrared diffuse reflectance spectroscopy with chemometric methods

Great attention has been paid to near-infrared diffuse reflectance spectroscopy (NIRDRS) due to its practicability in analyzing real complex samples. However, the application of the technique in micro-analysis is badly restricted by its low sensitivity or high detection limit. In this study, the possibility of achieving the sensitive detection of micro-components using NIRDRS with the help of chemometric methods is studied with two experimental datasets. The results show that a very high sensitivity can be obtained when the noise and the variant background are minimized. Quantitative determination of low concentrations of pesticides and trace Cr3+ in solutions is achieved by using preconcentration and chemometric approaches to minimize the noise and background. The absolute prediction error of the method can be as low as 7.6 mu g for the pesticide and 28.6 mu g for Cr3+. These quantities are equivalent to 76 ng mL(-1) and 286 ng mL(-1) if 100 mL of solution are used for the analysis.