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The possibility of combining solid-phase extraction of natural catecholamines (adrenaline, norepinephrine, and dopamine) on a microcolumn filled with hypercrosslinked polystyrene with their subsequent spectrophotometric or solid-phase spectroscopic determination in an eluate using gold nanorods or their nanocomposites with polyurethane foam has been investigated. The desorption of catecholamines from hypercrosslinked polystyrene by various eluents has been studied. It has been shown that the quantitative elution of all three catecholamines is achieved using 6 M acetic acid, which as an eluent is well combined with the proposed determination options. The features of a dynamic sorption extraction of catecholamines from urine and blood serum have been described. It allows you to reduce the influence of the matrix components and increase the analysis sensitivity by concentrating. The average concentration coefficient is 10–56 with sample volumes of 10–300 mL. The developed methods make it possible to determine catecholamines in urine at the level of their normal content. [ABSTRACT FROM AUTHOR]

A possibility of using a monitor calibrator for the determination of luminescent compounds is shown on an example of quinine. The determination is based on the irradiation of a sample with broadband radiation in the visible and near UV spectral regions from a built-in source exciting phosphor molecules and the simultaneous registration of the radiation incident on the detector. Measurement conditions are selected. Quinine can be determined in the range of 60−750 µM, the limit of detection is 20 µM. The determination is not affected by common inorganic ions, as well as sweeteners and acidity regulators present in many beverages. The developed method of determination is applicable to the analysis of carbonated drinks and drugs. Compared to a traditional spectrofluorimeter, monitor calibrator is characterized by compactness, mobility, ability of detecting luminescence in cuvettes of various sizes and shapes, and lower cost. [ABSTRACT FROM AUTHOR]

The second and final part of the review. Provides general information about sub- and supercritical extraction (pressurized liquid extraction, subcritical water extraction, supercritical fluid extraction), matrix solid-phase dispersion and the QuEChERS method. Based on an analysis of review works, information on the features of sample preparation using these methods is systematized, experimental parameters affecting extraction efficiency are considered, and examples of using these methods for isolating organic compounds in the analysis of solid environmental samples, food products, and plants are given. [ABSTRACT FROM AUTHOR]

The first part of the review provides general information about the solvent extraction of organic compounds from solid samples and discusses various methods for its implementation: extraction in a Soxhlet apparatus, ultrasonic extraction, microwave-assisted extraction. Based on an analysis of review papers, information on the features of sample preparation using these methods is systematized, experimental parameters affecting extraction efficiency are considered, and examples of using these methods for isolating organic compounds in the analysis of solid environmental samples, food products, and plants are given. [ABSTRACT FROM AUTHOR]

Dispersive solid-phase extraction (DSPE) and magnetic solid-phase extraction (MSPE) are methods of solid-phase sorption preconcentration. Compared to classical solid-phase extraction, these methods have a number of advantages, such as reduced consumption of sorbents and solvents, extraction time, and cost of analysis. The popularity of the method among the analysts is evidenced by the large number of reviews we have summarized in this publication. Information is systematized on different versions of these methods, differing in the way the preconcentration process is carried out, the nature of the sorbents used, and their combination with methods for the subsequent determination of the preconcentrated substances; examples of using DSPE and MSPE for the separation of organic compounds in the analysis of environmental samples, food products and biological fluids are given. [ABSTRACT FROM AUTHOR]

Published data on various versions of the homogeneous liquid–liquid microextraction (HLLME) of organic compounds are generalized and systematized, and a classification of these versions is given. The main HLLME procedures are discussed. Examples of the application of HLLME to the separation of organic compounds in the analysis of environmental samples, food products, and biological fluids are given. [ABSTRACT FROM AUTHOR]

The use of hypercrosslinked polystyrene for the group sorption preconcentration of catecholamines is proposed. The conditions for the preconcentration of noradrenaline, adrenaline, and dopamine are optimized: a microcolumn (10 × 6 mm), mass of adsorbent 0.03 g, 25 mL of solution (pH ~ 8.5), and transmission rate of the solution 1.0 mL/min. Compounds were desorbed with 1 mL of 6 M acetic acid and determined in the eluate by reversed-phase HPLC with an amperometric detector (E = 0.8 V). Adsorption preconcentration ensures the reduction of the limits of detection for catecholamines by more than 20 times. The limits of detection were 0.7 ng/mL for dopamine and 1 ng/mL for noradrenaline and adrenaline. The procedure was applied to the analysis of model mixtures based on urine. [ABSTRACT FROM AUTHOR]

The results of studies on the use of gold and silver nanoparticles in methods of optical molecular absorption spectroscopy, performed at the Division of Analytical Chemistry, Department of Chemistry, Moscow State University for the last 8 years, are summarized. The main methods for the synthesis of nanoparticles with different charges and morphology (spherical nanoparticles, nanorods, triangular nanoplates), as well as their nanocomposites, are considered. The developed options for using nanoparticles and their nanocomposites as reagents in spectrophotometry, solid-phase spectroscopy, and colorimetry are discussed. Examples of the determination of chemical compounds and ions using these reagents are given. [ABSTRACT FROM AUTHOR]

Single-drop microextraction (SDME) and hollow-fiber membrane microextraction (HFME) belong to methods of the liquid-phase microextraction preconcentration of organic compounds. These methods are characterized by the low consumption of organic solvents, high preconcentration factors, simplicity, low cost, ease of combination with various chromatographic methods; processes of preconcentration and sample injection are combined in a single device. Since the emergence of SDME (1996) and HFME (1999), a large number of versions have been developed that differ in the preconcentration technique, nature of the extractants used, and combinations with methods for the subsequent determination of the preconcentrated substances. The popularity of these methods among the analysts is evidenced by many reviews that we have summarized in this publication. [ABSTRACT FROM AUTHOR]

Dispersive liquid–liquid microextraction (DLLME) is one of the most promising methods of the microextraction preconcentration of organic compounds. This method is eco-friendly, simple, and universal; in comparison with conventional extraction, the consumption of the reagents and solvents, the time of extraction, and the cost of analysis in this method are reduced. For a short time from the moment of the appearance of DLLME in 2006, analysts developed numerous versions, differing by the method of dispersion, the nature of the extractant and by combinations with other methods of sample preparation and methods of the subsequent determination of the preconcentrated substances. The popularity of the method among the analysts is attested in a great number of reviews summarized in this publication. [ABSTRACT FROM AUTHOR]

Organic sensor arrays based on photonic crystals of submicrometer polystyrene particles, coated by a layer of polydimethylsiloxane, were studied using diffuse reflectance spectroscopy. The spectral characteristics obtained on instruments with different measurement geometries are compared. The conditions for obtaining the most informative analytical signal of sensor arrays based on photonic crystals are selected. Under the proposed conditions, the kinetic differences in the operation of these arrays upon exposure to nonpolar organic solvents (toluene and o-xylene) are compared. The work was performed at the Division of Analytical Chemistry, Department of Chemistry, Moscow State University. [ABSTRACT FROM AUTHOR]