442
H. M. Heise
[5]. In Fig. 20.3, the drying process of a blood sample is illustrated, for which as
substrate gold-coated abrasive paper had been used allowing for a diffuse reflection
measurement. Whereas in the beginning of the drying process the spectral features
are dominated by the water spectrum, absorption features of blood proteins with
albumin and hemoglobin as important representatives, become evident after some
time lapses. The similarity of NIR spectra of different proteins will be discussed
later.
However, another aspect of NIR spectroscopy of different substances is presented
by showing some model compound spectra. In Fig. 20.4, several carbohydrates of
special medical importance are shown. As examples of sugars, the monosaccharide
glucose and the disaccharide sucrose are shown, all measured as crystalline powders.
In addition, two polysaccharides, i.e., cellulose and starch, are also presented. While
the crystalline substances show much fine structure due to the crystalline state, the
other two have rather broad absorption band signatures. With Fig. 20.5, even quantitative data are provided for glucose as measured in aqueous solution and in a glassy state
from preparations starting from high-concentrated syrup samples, showing similar
band structures as the polysaccharides with glucose as structural subunits. Starch, for
example, consists of two types of polysaccharides, which are the linear and helical
amylose and branched amylopectin. Glycogen, as the glucose store of humans, is
a more highly branched amylopectin, but with a similar spectrum. In addition to
glucose, also a fructose spectrum from a glassy state preparation is shown, illustrating
the spectral differences within the combination band region above 4000 cm
−1 , which
is sufficient for quantitative discrimination. This aspect will later be discussed again
Fig. 20.3 Diffuse reflection spectra of blood during dry-film preparation by water evaporation.
Blood samples had been placed on diffusely reflecting substrates (gold-coated abrasive paper) and
were measured after different time lapses
H. M. Heise
[5]. In Fig. 20.3, the drying process of a blood sample is illustrated, for which as
substrate gold-coated abrasive paper had been used allowing for a diffuse reflection
measurement. Whereas in the beginning of the drying process the spectral features
are dominated by the water spectrum, absorption features of blood proteins with
albumin and hemoglobin as important representatives, become evident after some
time lapses. The similarity of NIR spectra of different proteins will be discussed
later.
However, another aspect of NIR spectroscopy of different substances is presented
by showing some model compound spectra. In Fig. 20.4, several carbohydrates of
special medical importance are shown. As examples of sugars, the monosaccharide
glucose and the disaccharide sucrose are shown, all measured as crystalline powders.
In addition, two polysaccharides, i.e., cellulose and starch, are also presented. While
the crystalline substances show much fine structure due to the crystalline state, the
other two have rather broad absorption band signatures. With Fig. 20.5, even quantitative data are provided for glucose as measured in aqueous solution and in a glassy state
from preparations starting from high-concentrated syrup samples, showing similar
band structures as the polysaccharides with glucose as structural subunits. Starch, for
example, consists of two types of polysaccharides, which are the linear and helical
amylose and branched amylopectin. Glycogen, as the glucose store of humans, is
a more highly branched amylopectin, but with a similar spectrum. In addition to
glucose, also a fructose spectrum from a glassy state preparation is shown, illustrating
the spectral differences within the combination band region above 4000 cm
−1 , which
is sufficient for quantitative discrimination. This aspect will later be discussed again
Fig. 20.3 Diffuse reflection spectra of blood during dry-film preparation by water evaporation.
Blood samples had been placed on diffusely reflecting substrates (gold-coated abrasive paper) and
were measured after different time lapses