10 Chemometric Analysis of Raman and IR Spectra of Natural Dyes
291
one of the most noteworthy example of carotenoid mapping in the biological tissue is reported by S. gamsjaeger et al. [71]. the study presents the in situ discrimination of carotenoid pigments (carotens and xanthophylls) beside the flavonoid substances (anthocyanins and flavonols) in petals of Viola x wittrockiana (Fig. 10.9).
the spectra were collected with laser with wavelength at 1,064 nm.
these results confirm that chemical differences in flower petals correlated to the
molecular structure of pigments can be directly detected by Raman spectroscopy
combines with hCA. It is worth to notice that in this case, the whole “fingerprint”
spectral range (1,000–1,700 cm
−1
) was analyzed which includes all Raman bands
from the flower matrix e. g. lignin and cellulose.
the three lowest rows of Fig. 10.9 display the distribution of carotenoids, anthocyanins and flavonols obtained from the integrate band intensity within the spectral
marker regions individually defined for the every pigment. this technique gives the
information about the relative pigment concentrations. the map of carotene distribution was created by using the band around 1,156 cm
−1
because it shows little or no
overlap with Raman bands ascribed to flavonol or anthocyanin derivatives, which
were analyzed simultaneously.
the more detailed Ft-RS study of carotenoids was conducted by Schulz et al.
[11] for Calendula officinalis L. the distribution of carotenoids with different
lengths of conjugated double-bond chain: auroxanthin (7), luteoxanthin (8) lutein
(9) and antheraxanthin (9), was shown (Fig. 10.10).
the carotenoids were analyzed also in the algal cell. By using the Ft-Raman
microimaging, the astaxanthin (classified as xanthophyll) was in situ and in vivo detected in Haematococcus pluvialis [72]. It was revealed that the structure of astaxanthin in algal cell is different from the structure of synthetic compound, what was
explained by the change of the chemical environment of the carotenoid chain. the
Raman maps of carotenoid distribution in the algal species Neochloris oleobundans
was reported in ref. [73]. the carotenoid compound was detected simultaneously
with lipids (triglyceride).
the resonance Raman effect is applied in the measurement of macular carotenoids in the human eye. the medical studies suggest that macular pigment, lutein
and zeaxanthin, protects against visual loss from age-related macular degeneration,
the leading cause of irreversible blindness [74]. the analyses can be carried out in
vivo, with the green or blue lasers [75–77]. the similar studies on Raman detection
of carotenoids were conducted also on human blood [78] and skin [79].
In regard of similarity in chemical structure between carotenoids and parrodienes, the Raman analysis of these pigments has a similar requirements. Polyenes are
detected, usually accompanied by carotenoids, i.e. in corals [13, 80] and molluscan
shells [81, 82]. the two major bands are observed at ca. 1,500 cm
−1
(v C = C) and
1,130 cm
−1
(v C-C) for all specimens [80].
Raman spectroscopy can be used for in situ quantitative measurements of carotenoids. the analysis of crocetin in saffron ( Crocus sativus L.) was carried out
with applying of RS and chemometrics [83]. A rapid method for determining the
crocetin esters and colouring strength directly in saffron samples, using NIR Raman spectroscopy (785 nm) together with partial least-square regression (PLS) was
291
one of the most noteworthy example of carotenoid mapping in the biological tissue is reported by S. gamsjaeger et al. [71]. the study presents the in situ discrimination of carotenoid pigments (carotens and xanthophylls) beside the flavonoid substances (anthocyanins and flavonols) in petals of Viola x wittrockiana (Fig. 10.9).
the spectra were collected with laser with wavelength at 1,064 nm.
these results confirm that chemical differences in flower petals correlated to the
molecular structure of pigments can be directly detected by Raman spectroscopy
combines with hCA. It is worth to notice that in this case, the whole “fingerprint”
spectral range (1,000–1,700 cm
−1
) was analyzed which includes all Raman bands
from the flower matrix e. g. lignin and cellulose.
the three lowest rows of Fig. 10.9 display the distribution of carotenoids, anthocyanins and flavonols obtained from the integrate band intensity within the spectral
marker regions individually defined for the every pigment. this technique gives the
information about the relative pigment concentrations. the map of carotene distribution was created by using the band around 1,156 cm
−1
because it shows little or no
overlap with Raman bands ascribed to flavonol or anthocyanin derivatives, which
were analyzed simultaneously.
the more detailed Ft-RS study of carotenoids was conducted by Schulz et al.
[11] for Calendula officinalis L. the distribution of carotenoids with different
lengths of conjugated double-bond chain: auroxanthin (7), luteoxanthin (8) lutein
(9) and antheraxanthin (9), was shown (Fig. 10.10).
the carotenoids were analyzed also in the algal cell. By using the Ft-Raman
microimaging, the astaxanthin (classified as xanthophyll) was in situ and in vivo detected in Haematococcus pluvialis [72]. It was revealed that the structure of astaxanthin in algal cell is different from the structure of synthetic compound, what was
explained by the change of the chemical environment of the carotenoid chain. the
Raman maps of carotenoid distribution in the algal species Neochloris oleobundans
was reported in ref. [73]. the carotenoid compound was detected simultaneously
with lipids (triglyceride).
the resonance Raman effect is applied in the measurement of macular carotenoids in the human eye. the medical studies suggest that macular pigment, lutein
and zeaxanthin, protects against visual loss from age-related macular degeneration,
the leading cause of irreversible blindness [74]. the analyses can be carried out in
vivo, with the green or blue lasers [75–77]. the similar studies on Raman detection
of carotenoids were conducted also on human blood [78] and skin [79].
In regard of similarity in chemical structure between carotenoids and parrodienes, the Raman analysis of these pigments has a similar requirements. Polyenes are
detected, usually accompanied by carotenoids, i.e. in corals [13, 80] and molluscan
shells [81, 82]. the two major bands are observed at ca. 1,500 cm
−1
(v C = C) and
1,130 cm
−1
(v C-C) for all specimens [80].
Raman spectroscopy can be used for in situ quantitative measurements of carotenoids. the analysis of crocetin in saffron ( Crocus sativus L.) was carried out
with applying of RS and chemometrics [83]. A rapid method for determining the
crocetin esters and colouring strength directly in saffron samples, using NIR Raman spectroscopy (785 nm) together with partial least-square regression (PLS) was