ABSTRACT
Direct absorption spec:troscopv. In direct absorption spectroscopy, the light intensity transmitted through or reflected by the analyte is measured. This techniquc is especially suitable for colorimetry measurements on surfaces and in non-turbid liquids and for analyzing compounds with non-interfering spectra. In many cases, the measurement selectivity in complex media can be improved through the use of multivariate data analysis methods such as artificial neural networks, the non-negative least mean squares method, or other noise suppression algorithms. Chemically mediated spectroscopy. In chemically mediated spectroscopy, the analyte interacts with a chemical; the analyte's status is indirectly obtained by measuring the spectral properties of the chemical. Different kinds of sensors based on chemically mediated spectroscopy can be used for measuring the physical, chemical, and biochemical parameters, since the indicator chemical may be adjusted to provide selectivity to a specific parameter 9.
