Irina A. Ananieva

Separation and enantioseparation of derivatized amino acids and biogenic amines by high-performance liquid chromatography with reversed and chiral stationary phases

This study demonstrates that an amino-beta-cyclodextrin-bonded phase column exhibits enantioselectivity for various amino acid derivatives. Mixtures of methanol, acetonitrile, tetrahydrofuran or dioxan and triethylamine buffers (pH 4.0-7.0) were used as mobile phases. The effect of the mobile phase on the resolution process was studied by varying the mobile phase composition (type and percentage of organic modifiers, pH, and ionic strength of the buffer solution). The 1-octanol-water partition coefficients are calculated and tabulated for 16 derivatized amino acids. The chromatographic data for 42 pairs of derivatized amino acids resolved on the amino-beta-cyclodextrin-bonded phase are summarised. The separation of adrenaline, noradrenaline and amphetamine on a novel vancomycin stationary phase is demonstrated.

Ultra-Micro-Thermal Field-Flow Fractionation

Abstract Micro-thermal field-flow fractionation, proposed conceptually and implemented experimentally several years ago, has developed rapidly in terms of theory, instrumentation, and numerous applications for the analysis and characterization of polymers and particles of synthetic, natural, and biological origin. Although the advances have been important, achieving the ultimate limits of miniaturization imposed by the physics as well as by recent technologies represents a challenge that was explored. The result of the reported experimental study is a new separation channel for ultra-micro-thermal field-flow fractionation, which was compared, in terms of performance, with the existing compact micro-thermal field-flow fractionation unit. The limits of the miniaturization are experimentally demonstrated with the use of suspensions of colloidal particles, which represent a more difficult case of separation than polymers in solution.

RAPID METHOD FOR THE DETECTION OF METABOLITE OF SULFUR MUSTARD 1,1′-SULFONYLBIS[2-S-(N-ACETYLCYSTEINYL)ETHANE] IN PLASMA AND URINE BY LIQUID CHROMATOGRAPHY-NEGATIVE ELECTROSPRAY-TANDEM MASS SPECTROMETRY

A method for detection of an important biological marker, 1,1′-sulfonylbis[2-S-(N-acetylcysteinyl)ethane] (SBSNAE) of sulfur mustard agent [bis-(2-chloroethyl)sulfide] (HD) in human plasma and rat urine to quantify HD exposure, is presented. It employs solid-phase extraction sample preparation, followed by liquid-chromatography-negative ion-electrospray ionization-tandem mass spectrometry. The method limit of detection (LOD) for SBSNAE is 0.05 ng/mL for rat urine samples with relative standard deviations of less than 10%. Application of this procedure was demonstrated in the HD animal exposure model. Rats were exposed intravenously to 5 mg/kg HD, and SBSNAE levels in urine samples were analyzed for 22 days post-exposure.

New separation materials based on gold nanoparticles

Purpose – Gold clusters supported on oxide surface are most promising as active sites as biochemical sensors, in optical industry and catalysis, but there is no information about application of these nanoparticles in analytical chemistry for the chromatographical separation of organic compounds. Thus, the aim of this paper is the development of new separation systems based on gold nanoparticles.Design/methodology/approach – The novel nanohybride system based on gold nanoparticles, cysteine and inorganic matrixes was synthesis. The results were obtained by the combined approach consisting quantum‐chemical calculations, direct organic synthesis and using chromatography investigation of obtained sorbent for separation of aminopyridines.Findings – The structure optimization of cysteine‐gold cluster complexes reveals that adsorbed acid greatly changes the structure of gold nanoparticle and, consequently, changes its properties. The most bond energy is calculated for L‐form 82 kcal/mol. Material based on alumin...

Dilute-and-shoot rapid-separation liquid chromatography tandem mass spectrometry method for fast detection of thiodiglycolic acid in urine

A new sensitive rapid-separation liquid chromatography tandem mass spectrometry approach for the determination of thiodiglycolic acid (TDGA) in urine has been developed. The use of the “dilute-and-shoot” method helps to shorten the sample preparation stage and provides a sensitive and direct approach for TDGA determination in urine. Chromatographic separation of the analyte and other urine compounds was achieved using a reverse-phase liquid chromatography column with mobile phases consisting of 0.1% formic acid in water and acetonitrile in a gradient elution mode. For the identification and quantification of TDGA electrospray ionization-tandem mass spectrometry monitoring, two precursor-to-product ion transitions were used. The method demonstrates good linearity and has a detection limit of 50 ng mL−1 in urine.

Use of gold nanoparticles for immobilization of L-cysteine on TLC plates

A new method of immobilization of the chiral selector on the surface of TLC plates by means of stepwise impregnation by gold nanoparticles and L-cysteine is described. The novel silica- and alumina-based stationary phases for TLC demonstrate enantioselectivity toward tetrahydrozoline, hydroxyzine, ketoprofen, fenoprofen, pindolol, and fluoxetine. The influence of the composition of the mobile phase on the Rf values and enantioselectivity is also discussed.

Micro-thermal field-flow fractionation in the characterization of macromolecules and particles: Effect of the steric exclusion mechanism

Abstract The influence of the steric exclusion mechanism on the dependence of the retention on the thickness of the micro-TFFF channel was studied theoretically. A good agreement of theory with experimental data was found. In order to preserve the use of micro-TFFF within an extended range of molar masses and particle sizes, the thickness of the channel cannot be reduced without taking into account a possible deterioration of the separation due to the contribution of steric exclusion to the separation mechanism.

Separation of water-soluble vitamins on silica modified with L-cysteine–stabilized gold nanoparticles using HPLC

Silica functionalized with 3-aminopropyltriethoxysilane and L-cysteine–stabilized gold nanoparticles has been obtained (SiO2–NH2–Au–L-cysteine). The influence of pH and the content of acetonitrile in the mobile phase on retention and separation selectivity of eight vitamins has been studied. The chromatographic conditions that enable the separation of C, B3, B12, B5 and B1, B2, B6, B10 mixtures of vitamins have been proposed. It has been found that it is possible to separate a mixture of vitamins C, B3, B12, and B5 in 8 min, and a mixture of vitamins B1, B2, B6, B10 in 12 min on the synthesized sorbent SiO2–NH2–Au–L-cysteine in isocratic elution mode.

HPLC separation of nitrogen-containing compounds on silica gel modified with gold nanoparticles stabilized by chitosan

The potentialities of using silica gel modified with gold nanoparticles stabilized by chitosan are evaluated in the normal phase of HPLC as an example of the separation of aniline and pyridine derivatives, as well as triazole fungicides by elution with mixtures of hexane with isopropyl alcohol, isobutanol, or chloroform. The influence of the nature and content of the polar additive on the efficiency and separation selectivity of the column have been studied. The possibility of separating mixtures containing penconazole, propiconazole, diniconazole, difenoconazole, and aminopyridines is shown.

Determination of the enantiomeric purity of albuterol on sorbents modified by macrocyclic antibiotics

The separation of albuterol enantiomers on sorbents with macrocyclic glycopeptide antibiotics immobilized on the silica surface was investigated. Commercial columns—Nautilus-E (BioKhimMak, Russia) with eremomycin as a chiral selector and ChirobioticTAG (Astec, United States) with teicoplanin aglycone as a chiral selector—were used for enantioseparation. Levalbuterol is the (R)-enantiomer of albuterol. We managed to separate albuterol enantiomers on both columns in a polar organic mode, but selectivity was higher on the ChirobioticTAG column (Rs = 1.7). The maximum resolution of enantiomer peaks (1.7) was observed in methanol–acetonitrile–triethylamine–acetic acid (90: 10: 0.05: 0.05) as the mobile phase. The detection limit of the compound calculated by a signal–background ratio of 3: 1 was 0.00002 mg/mL, which corresponds to 0.1% of (S)-enantiomer with respect to the total amount. The results made it possible to determine the enantiomeric purity of the active pharmaceutical substances of levalbuterol.