Recent advances in matrix-assisted laser desorption
ionization (MALDI) mass spectrometry imaging (MSI) have led to the direct
analysis of tissue slices. The major advantage of MSI is its capability of
simultaneously localizing and identifying a parent molecule and its metabolites
without any labeling or any prior knowledge. MSI has been extensively employed
to detect the differentiated pattern of lipids in various organs in different
diseases, such as brains in Alzheimer’s disease. Poor reproducibility of MALDIMSI analysis due to the heterogeneity of the matrix-analyte crystals, hindersits use on quantitative analysis. In addition, discontinuous ion flow due to
quickly consumption of the samples under laser irradiation on specific site
affects its ability in qualitative analysis. Although electrospray ionization
mass spectrometry (ESI-MS) cannot directly be used for imaging, ESI tandem mass
spectrometry (LC/ESI-MS/MS) can separate and distinguish gangliosides.
Paracetamol (acetaminophen) is one of the most popular
analgesic and antipyretic drugs. Paracetamol is available in different dosage
forms: tablet, capsules, drops, elixirs, suspensions and suppositories. Dosage
forms of paracetamol and its combinations with other drugs have been listed in
various pharmacopoeias. The combination of paracetamol with dipyrone is used asan antipyretic, analgesic and anti-inflammatory drug. Numerous methods have
been reported for the analysis of paracetamol and its combinations in pharmaceuticals
or in biological fluids. Paracetamol has been determined in combination with
other drugs using titrimetry, voltammetry, fluorimetry, colorimetry,
UV-spectrophotometry, quantitative thin-layer chromatography (TLC),
high-performance liquid chromatography (HPLC) and gas chromatography (GC) in
pharmaceutical preparations.
Effect of electrophilic and electrodotic groups on
the potentiometric titration of amides and other weak bases was studied.
Electrodotic groups enhance the potentiometric end point and electrophilicgroups depress it, sometimes to the extent that the compound is not titratable.
A combination of chloroform and acetic anhydride is a useful alternative medium
for the titration of weak bases. A potentiometric method for determination of p-acetamidophenol
was reported.
The idea of superatom was fruitful for the development of
nanophysics Superatom (quasiatomic nanoheterostructures) consists of a
spherical quantum dot (QD) with radius a, the volume of that contains the
semiconductor (or dielectric) material. QD is surrounded by dielectric(semiconductor) matrix. A hole is localized in the volume of QD, and the
electron is localized over a spherical interface (QD-matrix). In this
nanosystem the lowest electronic level is in matrix, and the lowest hole level
is within volume of QD. A large shift of the valence band (700 meV) generates
the localization of holes in the volume of QD. A significant shift of the
conduction band (about 400 meV) is a potential barrier for electrons.
