Fluorescence spectroscopy data collection

Kosovan P, Uhlflc F, Kuldova J, Stepanek M, limpouchova Z, Prochazka K, Benda A, Humpolickova J, Hof M (2011) Monte Carlo simulatimi of fluorescence correlation spectroscopy data. Collect Czechoslov Chem Cramnun 76(3) 207-222... 

In a large portion of routine and discovery-oriented analyses, mass spectrometry (MS) is used as a qualitative technique. The obtained qualitative data enable detection and structural elucidation of molecules present in the analyzed samples. However, modern chemistry and biochemistry heavily rely on quantitative information. In biochemistry it is often sufficient to conduct quantification of analytes in biofluids every few hours, days, or even weeks. In the real-time monitoring of highly dynamic samples, it is necessary to collect data points at higher frequencies. When it comes to selection of techniques for quantitative analyses, especially in the monitoring of dynamic samples, MS has not generally been favored. In fact, the performance of MS in quantitative analysis is worse than that of optical spectroscopies - especially, ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy. 

After NMR, UV-vis and fluorescence spectrometry are probably the most widely used techniques for thermodynamic data collection. Both require UV-vis absorbance (and in the case of fluorescence, emission) of the host and/or the guest. It is also important that upon complex formation the absorbance or emission change. Both analytical techniques can be approached in a very similar fashion because of its wider popularity, we emphasize here UV-vis spectroscopy. 

As we will see further in this chapter, knowing the structure of the data plays a fundamental role when applying any multiway technique. For illustrating this, we will comment on the data collected from the two most popular instrumentations used in food sciences nowadays that are able to produce multiway data Excitation-emission fluorescence spectroscopy (EEM) and hyphenated chromatographic systems (i.e. gas chromatography connected to mass spectrometry—GC-MS). The benefit and drawbacks of both techniques in the framework of food analysis will be discussed in successive chapters. Here we will just focus on the stmcture of the three-way array. Figure 1 shows the final three-way structure that is obtained when several samples are analysed by both EEM and hyphenated chromatography. However, the inner structure of this tensor varies due to the different nature of the measurement... 

There have been relatively little ultraviolet-visible (UV-Vis) spectroscopic data for 1,4-oxazines, but selected data are presented in Table 8. UV spectroscopy is important for photochromic compounds, such as spirooxazines. The UV spectra of 33 spirooxazines in five different solvents are collected in a review <2002RCR893>, and the more recently reported examples of photochromic oxazines 65, 66, 101, and 102 are shown here. It can be seen from Table 8 that both adding methoxy substituents to the oxazine and changing to a more polar solvent give a UV maximum at a higher wavelength. This solvent effect can also be seen in the case of 102, which also has important fluorescence properties, discussed in Section 8.06.12.2. 

From the analysis of the data in the LIPID AT database (41), more than 150 different methods and method modifications have been used to collect data related to the lipid phase transitions. Almost 90% of the data is accounted for by less than 10 methods. Differential scaiming calorimetry strongly dominates the field with two thirds of all phase transition records. From the other experimental techniques, various fluorescent methods account for 10% of the information records. X-ray diffraction, nuclear magnetic resonance (NMR), Raman spectroscopy, electron spin resonance (ESR), infrared (IR) spectroscopy, and polarizing microscopy each contribute to about or less than 2-3% of the phase transition data records in the database. Especially useful in gaining insight into the mechanism and kinetics of lipid phase transitions has been time-resolved synchrotron X-ray diffraction (62,78-81). 

In the columns identifying the experimental method, MW stands for any method studying the pure rotational spectrum of a molecule except for rotational Raman spectroscopy marked by the rot. Raman entry. FUR stands for Fourier transform infhired spectroscopy, IR laser for any infiured laser system (diode laser, difference frequency laser or other). LIF indicates laser induced fluorescence usually in the visible or ultraviolet region of the spectrum, joint marks a few selected cases where spectroscopic and diffraction data were used to determine the molecular structure. A method enclosed in parentheses means that the structure has been derived from data that were collected by this method in earlier publications. The type of structure determined is shown by the symbols identifying the various methods discussed in section II. V/ refers to determinations using the Kraitchman/Chutjian expressions or least squares methods fitting only isotopic differences of principal or planar moments (with or without first... 

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