Microparticle spectroscopy

Axelrod D, Hellen EH, Fulbight RM (1992) Microparticle fluorescence. In Lakowicz JR (ed) Topics in fluorescence spectroscopy, vol 3, Biochemical applications. Plenum, New York, pp 289-343... 

We have seen that the electrical field associated with electromagnetic radiation plays an important role in elastic scattering and in microparticle heating. It plays a no less important role in the inelastic scattering processes of fluorescence and Raman spectroscopy, which we examine next. 

The studies of Tallin and Buehler indicate that microparticle spectroscopic techniques can be used to follow gas/microparticle chemical reactions. The use of morphological resonances to determine the refractive index of a reacting droplet has limited applicability because there must be a unique relationship between composition and refractive index to allow the method to be used to follow chemical reactions. Raman spectroscopy has broader applications, but one must deal with morphological resonances if droplets are... 

This review of the chemistry and physics of microparticles and their characterization is by no means comprehensive, for the very large range of masses that can be studied with the electrodynamic balance makes it possible to explore the spectroscopy of atomic ions. This field is a large one, and Nobel laureates Hans Dehmelt and Wolfgang Paul have labored long in that fruitful scientific garden. The application of particle levitation to atmospheric aerosols, to studies of Knudsen aerosol phenomena, and to heat and mass transfer in the free-molecule regime would require as much space as this survey. 

Resonant and non-resonant laser post-ionization of sputtered uranium atoms using SIRIS (sputtered initited resonance ionization spectroscopy) and SNMS (secondary neutral mass spectrometry) in one instrument for the characterization of sub-pm sized single microparticles was suggested by Erdmann et al.94 Resonant ionization mass spectrometry allows a selective and sensitive isotope analysis without isobaric interferences as demonstrated for the ultratrace analysis of plutonium from bulk samples.94 Unfortunately, no instrumental equipment combining both techniques is commercially available. 

Microparticles. More than 200 particles collected at Whiteface Mountain in the fine fraction (<2.5 pm) on 27 July I and IV, 28 July II, III and IV and 29 July I (where 1=0000-0600 hours, 11=0600-1200 hours, 111=1200-1800 hours, IV=1800-2400 hours) were characterized by electron diffraction, energy-dispersive x-ray spectroscopy (EDXRS) and morphology with transmission and high-voltage EM. 

Microspheres intended for nasal administration need to be well characterized in terms of particle size distribution, since intranasal deposition of powder delivery systems is mostly determined by their aerodynamic properties and particle sizes. Commonly used methods for particle size determinations described in the literature are sieving methods [108], light microscopy [58], photon correlation spectroscopy [66], and laser diffractometry [25,41,53,93], The morphology of the microparticles (shape and surface) has been evaluated by optical, scanning, and transmission electron microscopy [66, 95],... 

The SBH microparticles were encapsulated within polymer films by the LBL self-assembly of oppositively charged polyelectrolytes (PEI and PABA). The polymer nanofilms fabrication was performed using dichloromethane as a working media. IR-spectroscopy was applied to investigate the chemical interaction between the polyelectrolytes. For preparation of the microcontainers, SBH powder was dispersed in DCM. PABA and PEI were adsorbed sequentially onto the surface of SBH particles. Finally, SBH particles were coated with three double layers of PABA and PEI. 

Shakesheff KM, Evora C, Soriano I, et al. The adsorption of poly(vinyl alcohol) to biodegradable microparticles studied by x-ray photoelectron spectroscopy (XPS). J Colloid Interface Sci 1997 185(2) 538-547. 

Metal oxide and hydroxide systems serve many functions, including roles as pigments, in mineralogy, and also in catalysis. The classic techniques used in such investigations have included diffraction (especially X-ray diffraction XRD), thermal analysis, transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy (see also Chapters 2 and 4). Until the introduction of voltammetry in the analysis of immobilized microparticles, electrochemical studies had been confined to solid electrolyte cells (Chapter 12), normally functioning at elevated temperatures. Unfortunately, these studies proved to be inapplicable for analytical characterization, and consequently a series of systematic studies was undertaken using immobilized microparticles of iron oxides and oxide-hydrates (for reviews, see... 

The characterization of polymers often reqnires the separation of the other components, including otganic components. It is based on the nse of density gradients or organic solvents. Quantification nsing imaging is adapted for large objects, but there is a problem in the case of microparticles. In this case, the use of infrared spectroscopy (in transmission or reflection mode) which compares the spectra of samples to the spectra of a reference is the most appropriate method to characterize polypropylenes, polyethylenes and polyesters. Raman spectroscopy is sometimes used, as well as calorimetry, for the characterization of the fumes after combustion. 

The use of Fourier-transformed infrared spectroscopy (FTIR) in particles produced by spray chilling mainly predicts the detection of possible interactions between the active ingredient and the lipid carrier. Normally, the analysis individually studies the components (matrix and active compound, and other components, when available) that will form the capsules. Specific absorption bands will be observed in determined regions or in a specific wavelength. After that, the analysis of the microparticles that are already formed is carried out. The discussion involves changes in the absorption bands of ingredients and formed microparticles, with the comparison of the peaks observed in both cases. 

Fourier transform infrared (FT-IR) spectroscopy can be used to characterize drug substances, polymer blends, polymer complexes, dynamics, surfaces, and interfaces, as well as chromatographic effluents and degradation products. It provides information about the complexation and interactions between the various constituents in the PECs. It is capable of qualitative identification of the structure of unknown materials as well as the quantitative measurement of the components in a complex mixture. FT-IR spectra of physical mixture and PEC can be determined by FT-IR spectrophotometer using KBr disc method in the range of 4000 to 250 cm h Since the stability and drug substance is very important in several applications, determination of their physicochemical stability is crucial. The FTIR spectra of polyacrylic acid, PVP, metformin hydrochloride, and PEC microparticles of metformin were shown in Figure 56.8. The FTIR spectra of polyacrylic acid and PVP have shown... 

Dokko K., Shi Q., Stefan 1. C., Scherson D. A. In Situ Raman Spectroscopy of Single Microparticle Li -lntercalation Electrodes, J. Phys. Chem. B 2003,107,12549-12554. 

The main objective of our studies was to obtain green composites from corn starch matrix and various conventional [73, 76, 77], and non-conventional cellulose sources [78]. Previously, corn starch (St) was converted to starch microparticles (StM). Further, different organic acids (adipic, malic, tartaric) were used for treatment of StM in order to obtain chemically modified starch microparticles (CMSt) according to literature data [72]. After casting and water evaporation, the starch-based films were investigated by means of X-ray diffraction and FTIR spectroscopy methods. Opacity and water uptake of starch-based films were also evaluated. 

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