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Solid-phase extraction (SPE) is an effective analytical tool commonly used for the fractionation, preconcentration and purification of a component of interest from complex biological and environmental samples. 1 Unfortunately, the classical procedure of the SPE protocol optimization for the isolation of a number of analytes from multicomponent samples, particularly using the breakthrough curves method, can be expensive. This is because a quantitative amount of pure standards must be used. Moreover, such a procedure is usually time consuming, due to a number of fractions across a wide range of binary mobile phases for each analytical standard that should be collected and quantified. Therefore, an alternative method for the rapid computation of appropriate binary mixture concentrations and volumes for the purification and elution steps of a solid-phase extraction protocol based on e.g. the solvation parameter model have been proposed and tested. 2,3 On the other hand, the SPE cartridge can be considered as a short chromatographic column, and the retention of analytes in a such system should be simply predicted using retention data from HPLC experiment, in which a similar type of stationary phase and a wide range of solvent composition were studied. Recently, it has been suggested that planar chromatography may be used as a convenient pilot technique for estimating the SPE and HPLC behaviors of pesticide groups, separated under RP conditions. 4,5 The main advantage of such an approach is that on the plate a number of samples can be analyzed simultaneously, and therefore appropriate retention data can be collected within a relatively short period of time compared to the SPE or HPLC techniques.One of the advantages of modern HPTLC plates over classical TLC systems is that the eluent developing distance can be reduced to less than 50 mm, even for separations involving a non-forced developing mode. This idea is based on an observation that the minimum values of the plate height (H) can be achieved if the solvent migration distance along the HPTLC plate ranges from 30 to 40 mm. 6 Therefore, it can be expected that within and close to this migration distance range more dense spots can be obtained. In practice, under such conditions efficient separation for many types of compounds was observed, whereas the total analysis time was dramatically reduced compared to chromatographic separation performed on 10 or 20 cm long TLC plates. [7][8][9][10][11][12] Previously, it had been demonstrated that micro thin-layer chromatography performed on the wettable with water RP18 plates and organic/water mobile phases, can be a useful technique for estimating the SPE behavior of estetrol, which was eluted from octadecylsilica packed cartridges. 11 The main goals of present paper are to show the high separation throughput and capability of micro-planar chromatography as a fast and robust retention data source, as well as to demonstrate that this technique can be useful for an accurate prediction of the SPE behavior over a wide range of k...

Nanoparticles have an extended surface and a large surface area, which is the ratio of the size of the surface area to the volume. A functionalized surface can give rise to more modifications and therefore allows this nanomaterial to have new properties. Fluorescent molecules contain fluorophore, which is capable of being excited via the absorption of light energy at a specific wavelength and subsequently emitting radiation energy of a longer wavelength. A chemically modified surface of nanodiamond (ND; by carboxylation) demonstrated biocompatibility with DNA, cytochrome C, and antigens. In turn, fluorescent nanodiamonds (FNDs) belong to a group of new nanomaterials. Their surface can be modified by joining functional groups such as carboxyl, hydroxyl, or amino, after which they can be employed as a fluorescence agent. Their fluorescent properties result from defects in the crystal lattice. FNDs reach dimensions of 4-100 nm, have attributes such as photostability, long fluorescence lifetimes (10 ns), and fluorescence emission between 600 and 700 nm. They are also nontoxic, chemically inert, biocompatible, and environmentally harmless. The main purpose of this article was to present the medical applications of various types of modified NDs.

We report the results of experimental work focusing on host-guest supramolecular complex creation between macrocyclic compound (β-cyclodextrin) and 1-acenaphthenol enantiomers (racemic mixture) in liquid phase composed of 35% acetonitrile in water (v/v) at different temperatures ranging from 0 to 90 °C. Experimental setup involved several analytical protocols based on classical non-forced flow planar chromatography (RP-18 TLC plates), micro-TLC (RP-18 W HPTLC plates), column chromatography (HPLC with C-18 and C-30 stationary phases), as well as UV-Vis spectrophotometry and optical microscopy. It has been found that under various planar chromatographic conditions (stationary plates type, chamber shape and volume, development mode, and saturation) non-typical retention properties (extremely high retention) of 1-acenaphthenol at subambient temperatures can be observed. To our knowledge, reported experimental results are in opposition to currently described retention models based on column chromatographic investigation of host-guest complexes (where in case of strong interaction of given analyte with macrocyclic mobile phases additive, which itself is non strongly retarded by stationary phase—close to the retention of dead volume marker, the retention of target compounds is shortened at low temperatures). To explain this TLC phenomenon that may have in our opinion a number of practical applications, especially for selective high throughput separation involving microchromatographic and/or microfluidic devices as well fractionation and extraction protocols (using, e.g., bar extraction systems), several experiments were conducted focusing on (i) acenaphthenol chromatography under different instrumental conditions, (ii) cyclodextrin retention measured as analyte or mobile phase additive, (iii) plate development time under different mobile phases and temperature settings, (iv) various column chromatographic conditions including C-30 and two C-18 stationary phases, (v) UV-Vis spectrophotometry, and (vi) microscopy inspection of precipitated CD-acenaphthenol crystals. Analysis of collected data has revealed that the most probable reasons for TLC retention behavior of 1-acenaphthenol under β-cyclodextrin additive conditions can be associated with (i) solubility changes of created host-guest complex, (ii) kinetics of solid complex precipitation, and (iii) differences in analysis time between planar and column chromatography. Because precipitation phenomenon may have a massive impact on analytes quantification involving macrocycles as the mobile phase additives, our previously reported data concerning a number of low-molecular compounds (mainly steroids and non steroidal endocrine disrupting chemicals) using HPLC methodology based on binary mobile phases without and with β-cyclodextrin and its hydroxypropyl derivative were re-examined and results discussed. Considering these data and the whole data set reported presently, the enhanced model of chromatographic retention driven by host-guest interaction was proposed.Electronic s...