|
|
New approaches in drop coating deposition Raman spectroscopy for sensitive molecular detection
Přikryl, Mikuláš ; Kočišová, Eva (advisor) ; Holoubek, Aleš (referee)
in english: Drop coating deposition Raman spectroscopy is a vibrational spectroscopic method based on the principle of Raman scattering. Deposition of a small volume of solution (μl) of a low concentration (μM) on a special hydrophobic substrate and subsequent drying leads to a formation of a deposit from which we can accumulate a higher quality Raman spectrum than in the case of classical Raman spectroscopy. In this thesis, four contaminants (melamine, picloram, thiram, bentazone) were studied on new nanoparticle-based substrates prepared at our faculty. These hydrophobic substrates were compared to commercial substrates and proven to be suitable for further development. Next, artificially prepared mixtures of pairs of contaminants were studied using the commercial substrate. Every contaminant was detected and differentiated in each of these mixtures using factor analysis at relatively low concentrations. Furthermore, the contaminants were separated in some deposits. However, unknown spectra were detected, probably due to chemical reactions between the contaminants. Possibilities of contaminations or interactions with the substrate were eliminated. Finally, a real sample of infant formula artificially contaminated by melamine was studied. The contaminant was detected at concentrations equal to...
|
|
|
Drop coating deposition Raman spectroscopy of selected contaminants
Přikryl, Mikuláš ; Kočišová, Eva (advisor) ; Machalová Šišková, Karolína (referee)
in english: Drop coating deposition Raman spectroscopy is a special method of Raman spectroscopy based on a deposition of a small volume of solution or suspension on a special substrate with hydrophobic properties. The drop dries on this substrate and forms a deposit from which a Raman spectrum of good quality can be accumulated. This is possible in case of the small volume of deposited drop (several µl) and low initial concentration (µM) as well. The main goal of this thesis is to find the limits of this method for detection of several contaminants (melamine, picloram, thiram, bentazone) using two commercial substrates (SpectRIMTM , μ-RIMTM ) for study of aqueous solutions, and one non-commercial for study of ethanol solutions. Spectra accumulated on commercial substrates were generally of higher quality and therefore the detection limits were lower. Between the two commercial substrates, SpectRIMTM proved to be a more suitable choice due to the fact that contaminants were better concentrated on this substrate. The obtained detection limits were compared with the limits of these substances for surface enhanced Raman spectroscopy. Although the same limits were not reached, all substrates showed great potential for the detection of substances at very low concentrations.
|
guest ::
RSS feed.