10 Chemometric Analysis of Raman and IR Spectra of Natural Dyes
303
the distinguishing of the synthetic and natural indigo samples is possible with
the Raman spectroscopy combined with chemometric methods [112]. the extraction of the essential data was in that case carried out with the PCA as the spectral
pre-processing methods whilst the CA and the LdA methods enabled to get the
valuable information. this CA result enables to clearly distinguish between natural
and synthetic indigo. however, the distinction between natural samples made from
Indigofera tinctoria and Isatis tinctoria was not possible.
the analysis carrying out with the LdA method revealed that the bands at
1,582 cm
−1
and 1,571 cm
−1
(ascribed to the symmetric stretching modes of v(C = C),
v(C = o and v(C-C)) contribute to the discrimination between the natural and synthetic samples. moreover, also the region 300–900 cm
−1
seems to be significant for
sample discrimination.
It is also worth to look at the pre-processed spectra prepared for LdA method.
to minimize the background influence, the 1st and 2nd derivatives were taken from
spectra. the comparison of the results revealed that the 1st derivatives give the
worst effect than the untreated and 2nd derivatives spectra.
10.4 Summary
the use of chemometric methods in the analysis of Raman and IR spectra of dyes
has opened new possibilities in the areas previously reserved only for chromatographic methods or conventional uv-vis studies. In the future, the combination of
chemometrics with spectroscopic methods is likely to replace other measurement
techniques for dye analysis, traditionally applied in various fields from food quality
to drug control. the rapidity and simplicity together with the possibility of in situ
measurements are definitely the most attractive feature of these methods.
Acknowledgments AR thanks the project “Society–Environment–technologies” realized
within the human Capital operational Programme by Jagiellonian university for financial support.
References
1. de Rijke E, out P, Niessen WmA, Ariese F et al (2006) Analytical separation and detection
methods for flavonoids. J Chromatogr A 1112:31–63
2. melo mJ (2009) history of natural dyes in the ancient mediterranean world. In: Bechtold t,
mussak R (eds) handbook of natural colorants. Wiley, Chichester
3. Stuart Bh (2007) molecular spectroscopy. Analytical techniques in materials conservation.
Wiley, Chichester
4. Zollinger h (2003) Color chemistry: syntheses, properties, and applications of organic dyes
and pigments. Wiley, Chichester
5. general Introduction to the Chemistry of dyes (2008) Some aromatic amines, organic dyes,
and related exposures. IARC Working group on the Evaluation of Carcinogenic Risks to
humans
303
the distinguishing of the synthetic and natural indigo samples is possible with
the Raman spectroscopy combined with chemometric methods [112]. the extraction of the essential data was in that case carried out with the PCA as the spectral
pre-processing methods whilst the CA and the LdA methods enabled to get the
valuable information. this CA result enables to clearly distinguish between natural
and synthetic indigo. however, the distinction between natural samples made from
Indigofera tinctoria and Isatis tinctoria was not possible.
the analysis carrying out with the LdA method revealed that the bands at
1,582 cm
−1
and 1,571 cm
−1
(ascribed to the symmetric stretching modes of v(C = C),
v(C = o and v(C-C)) contribute to the discrimination between the natural and synthetic samples. moreover, also the region 300–900 cm
−1
seems to be significant for
sample discrimination.
It is also worth to look at the pre-processed spectra prepared for LdA method.
to minimize the background influence, the 1st and 2nd derivatives were taken from
spectra. the comparison of the results revealed that the 1st derivatives give the
worst effect than the untreated and 2nd derivatives spectra.
10.4 Summary
the use of chemometric methods in the analysis of Raman and IR spectra of dyes
has opened new possibilities in the areas previously reserved only for chromatographic methods or conventional uv-vis studies. In the future, the combination of
chemometrics with spectroscopic methods is likely to replace other measurement
techniques for dye analysis, traditionally applied in various fields from food quality
to drug control. the rapidity and simplicity together with the possibility of in situ
measurements are definitely the most attractive feature of these methods.
Acknowledgments AR thanks the project “Society–Environment–technologies” realized
within the human Capital operational Programme by Jagiellonian university for financial support.
References
1. de Rijke E, out P, Niessen WmA, Ariese F et al (2006) Analytical separation and detection
methods for flavonoids. J Chromatogr A 1112:31–63
2. melo mJ (2009) history of natural dyes in the ancient mediterranean world. In: Bechtold t,
mussak R (eds) handbook of natural colorants. Wiley, Chichester
3. Stuart Bh (2007) molecular spectroscopy. Analytical techniques in materials conservation.
Wiley, Chichester
4. Zollinger h (2003) Color chemistry: syntheses, properties, and applications of organic dyes
and pigments. Wiley, Chichester
5. general Introduction to the Chemistry of dyes (2008) Some aromatic amines, organic dyes,
and related exposures. IARC Working group on the Evaluation of Carcinogenic Risks to
humans