426
C. W. Huck
few NIR wavenumbers meaningful for regression of glucose and urea concentration
in artificial dialysate solutions are found, and these wavenumbers are located in the
regions free from a strong absorption of water (Fig. 19.6-I). Multilevel/multifactor
design was employed to cover the relevant concentration variations during dialysis. The results demonstrated that MIR spectroscopy is better suited to analyze the
molecules of interest. When employed in a multi-reflection ATR mode, it enables
reliable prediction of all target analytes. In contrast, the NIR spectroscopic method
did not give access to all five components but only to urea and glucose. However,
it offered advantages of practical nature, such as easy sampling. For both methods,
coefficients of determination R
2 are greater or equal to 0.86, as elaborated in the
test-set validation process for urea and glucose. The method applied to the analysis of lactate, phosphate and creatinine performed well in the MIR with R
2
≥ 0.95
using test-set validation (Table 19.2). This study indicates that there exists room for
improvement in the performance levels of NIR spectroscopy applied to hemodialysis
analysis (Table 19.2).
19.8 Examination of Entire Organisms
As mentioned, the underlying physical principles of NIR spectroscopy make it relatively more suitable for interrogation of high-volume samples such as entire biological organisms. As a good example, the properties of fish embryo have recently been
comprehensively examined in vivo at the molecular level by Ishigaki et al. [21]. The
authors used NIR spectroscopy and imaging for monitoring of the growth of fertilized
eggs of Japanese medaka fish. This approach enabled non-destructive examination
of the inner components such as proteins, lipids and water, over the 6200–4000 cm
–1
region. Changes in chemical structure of oil droplets and egg yolk over the time
period from the first day after fertilization to the day before hatching were monitored
(Fig. 19.7). The study demonstrated that NIR spectroscopy can decipher signs of
hatching and metabolic changes in the egg non-invasively. It was revealed that the
percentage of strongly hydrogen-bonded water in the oil droplets is larger than in
other parts and that yolk has quite different water environments from those found
in embryo parts. Furthermore, insights into secondary structure of proteins were
obtained. From characteristic bands at 5756 and 4530 cm
–1 appearance of membrane
structures was concluded.
19.9 NIR Studies of the Structure, Properties
and Interactions of Biomolecules
Exhaustive presentation of NIR spectroscopy in elucidating information on the
molecular structure, properties and interactions is included in Chapter 13 Overview of
C. W. Huck
few NIR wavenumbers meaningful for regression of glucose and urea concentration
in artificial dialysate solutions are found, and these wavenumbers are located in the
regions free from a strong absorption of water (Fig. 19.6-I). Multilevel/multifactor
design was employed to cover the relevant concentration variations during dialysis. The results demonstrated that MIR spectroscopy is better suited to analyze the
molecules of interest. When employed in a multi-reflection ATR mode, it enables
reliable prediction of all target analytes. In contrast, the NIR spectroscopic method
did not give access to all five components but only to urea and glucose. However,
it offered advantages of practical nature, such as easy sampling. For both methods,
coefficients of determination R
2 are greater or equal to 0.86, as elaborated in the
test-set validation process for urea and glucose. The method applied to the analysis of lactate, phosphate and creatinine performed well in the MIR with R
2
≥ 0.95
using test-set validation (Table 19.2). This study indicates that there exists room for
improvement in the performance levels of NIR spectroscopy applied to hemodialysis
analysis (Table 19.2).
19.8 Examination of Entire Organisms
As mentioned, the underlying physical principles of NIR spectroscopy make it relatively more suitable for interrogation of high-volume samples such as entire biological organisms. As a good example, the properties of fish embryo have recently been
comprehensively examined in vivo at the molecular level by Ishigaki et al. [21]. The
authors used NIR spectroscopy and imaging for monitoring of the growth of fertilized
eggs of Japanese medaka fish. This approach enabled non-destructive examination
of the inner components such as proteins, lipids and water, over the 6200–4000 cm
–1
region. Changes in chemical structure of oil droplets and egg yolk over the time
period from the first day after fertilization to the day before hatching were monitored
(Fig. 19.7). The study demonstrated that NIR spectroscopy can decipher signs of
hatching and metabolic changes in the egg non-invasively. It was revealed that the
percentage of strongly hydrogen-bonded water in the oil droplets is larger than in
other parts and that yolk has quite different water environments from those found
in embryo parts. Furthermore, insights into secondary structure of proteins were
obtained. From characteristic bands at 5756 and 4530 cm
–1 appearance of membrane
structures was concluded.
19.9 NIR Studies of the Structure, Properties
and Interactions of Biomolecules
Exhaustive presentation of NIR spectroscopy in elucidating information on the
molecular structure, properties and interactions is included in Chapter 13 Overview of