An adsorbent for HPLC, silica doubly layer-by-layer modified with 6,10-ionene and dextran sulfate, is obtained. The adsorbent has both hydrophobic and hydrophilic and ion-exchange properties (because of the presence of hydrophobic anions and cations on the surface). A possibility of using the obtained adsorbent in HPLC with tandem mass spectrometric detection is shown. The conditions for the separation of caffeine, paracetamol, doxylamine, and chlorpheniramine in the isocratic mode are selected in elution with mixtures of acetonitrile and an acetate buffer solution. The most successful results are achieved by eluting the separated substances with the mobile phase acetonitrile–15 mM acetate buffer solution (glacial acetic acid/ammonium acetate with pH 5.55 in the ratio 10 : 90, vol). Gradient elution conditions are selected, a methodology is developed for determining traces of pharmaceuticals in human serum in the multiple reaction monitoring (MRM) mode using the internal standard method. The source and MRM transition parameters are selected individually for each compound. The linear range of the calibration curve for paracetamol and caffeine is 0.5–200 ng/mL and for doxylamine and chlorpheniramine, 0.05–50 ng/mL. The concentration of pharmacologically active compounds of caffeine, paracetamol, doxylamine, and chlorpheniramine in the blood serum of patients taking appropriate drugs is 165.2, 17.3, 10.2, and 35.3 ng/mL, respectively.

Macrocyclic antibiotic eremomycin was revealed to be capable of stabilizing gold nanoparticles, and these eremomycinstabilized nanoparticles can be consequently adsorbed on the sorbent surface at the selector content of 0.017 mmol g–1. Silica gel modified with the adsorbed nanoparticles and eremomycin demonstrated a high enantioselectivity towards amino acids. The best separation of enantiomers was achieved in the cases of tryptophan, 3,4-dihydroxyphenylalanine and phenylalanine, the analysis time being less than 10min.

Synthesis of new sorbent and its application for separation of enantiomers of some biologically active compounds were suggested. It has been shown that macrocyclic antibiotic eremomycin is able to stabilize gold nanoparticles and these eremomycin-stabilized gold nanoparticles can be effectively adsorbed on the sorbent surface. Such sorbent has a number of advantages including simple and cheap way of obtaining and small selector consumption. Hydrophilic and acid-base properties of new sorbent were explored to understand its best using. It was found that the sorbent demonstrates a high enantioselectivity to amino acid in the enantioseparation by liquid chromatography.

Data on the use of macrocyclic antibiotics (vancomycin, teicoplanin, teicoplanin aglycone, and eremomycin) for the enantioseparation of amino acids, various amino acid derivatives, α-phenylcarboxylic acids, β-blockers, and some pharmaceutical preparations in reversed-phase and polar-organic HPLC modes are summarized. It is shown that mixed chiral selectors (eremomycin–vancomycin, eremomycin–bovine serum albumin) combine the properties of two selectors. Eremomycin and macrolides (azithromycin, erythromycin, and clarithromycin) are successfully used as chiral selectors in capillary electrophoresis. Aqueous and aqueous–organic supporting electrolytes ( SEs ) with the addition of eremomycin or nonaqueous supporting electrolytes with the addition of a macrolide are used for enantioseparation. The use of nonaqueous supporting electrolytes decreases the adsorption of the selectors on the quartz capillary surface and enables the separation of enantiomers at a low concentration of a chiral selector. Additions of boric acid into the supporting electrolyte improve the selectivity of separation.

A new chiral sorbent based on mercaptosilica modified by gold nanoparticles, then treated by 3-mercaptopropionic acid and macrocyclic antibiotic vancomycin, was obtained. The enantioseparation of isomeric β-blockers (nadolol, atenolol, metoprolol, alprenolol, oxprenolol, and pindolol) by HPLC was studied on the synthesized sorbent. The effect of the composition of the mobile phase (nature and concentration of the organic solvent, concentration and pH of the buffer solution) on retention times of β-blocker enantiomers, selectivity of separation, and resolution of chromatographic peaks were studied. The best separation was achieved for pindolol and metoprolol. The procedure was used to determine the pindolol enantiomers in the preparation “Visken,” and metoprolol in the “Vazocardin” preparation.

Обсуждается использование смешанных селекторов в газовой и высокоэффективной жидкостной хроматографии для разделения оптических изомеров. Они позволяют повысить универсальность хиральной фазы. В газовой хроматографии широко и успешно используются смеси модифицированного β-циклодекстрина. В ВЭЖХ наиболее изучены смешанные хиральные селекторы на основенизкомолекулярных селекторов и производных полисахаридов, в меньшей степени ̶ белков и макроциклических антибиотиков.

The use of sorbents modified by metal nanoparticles in HPLC for the separation of various organic substances is discussed. Authors’ data on the synthesis and study of silicas modified by gold nanoparticles stabilized by organic ligands are summarized. A possibility of the successful separation of nitroaniline, aminopyridine, hydrazines, water-soluble vitamins, β-blockers, and their enantiomers on the synthesized sorbents is shown.

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 ( R s = 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.

A mixed chiral sorbent based on silica with immobilized macrocyclic antibiotics eremomycin and vancomycin was synthesized. A possibility of the separation of enantiomers of β-blockers (metoprolol, pindolol, alprenolol, oxprenolol, labetalol, and atenolol) and amino acids (tryptophan, phenylalanine, DOPA, methionine, and acetyl glutamic acid) on this chiral sorbent by HPLC was studied. The influence of the composition of the mobile phase (pH of buffer solution, its concentration, content of organic modifier, and its nature) on the retention times of β-blocker and amino acid enantiomers, selectivity, and resolution of peaks was studied. It was shown that the mixed chiral sorbent has enantioselectivity to both classes of compounds, while silica modified with vancomycin has no ability to the separation of enantiomers of non-derivatized amino acids, and silica modified with eremomycin has no ability to the separation of β-blocker enantiomers. High values of resolution for amino acids (max Rs > 4) and β-blockers (max Rs > 1) were obtained.

New stationary phases for HPLC are obtained via layer-by-layer deposition of polyelectrolytes and studied: (1) silica gel modified layer-by-layer with 6,10-ionene and dextran sulfate (Sorbent 1); (2) silica gel twice subjected to the above modification (Sorbent 2); and (3) silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate (Sorbent 3). The effect the content of the organic solvent in the mobile phase and the concentration and pH of the buffer solution have on the chromatographic behavior of several pharmacologically active nitrogen-containing compounds is studied. The sorbents are stable during the process and allow the effective separation of beta-blockers, calcium channel blockers, alpha-agonists, and antihistamines. A mixture of caffeine, nadolol, tetrahydrozoline, pindolol, orphenadrine, doxylamine, carbinoxamine, and chlorphenamine is separated in 6.5 min on the silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate.

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.

A new silica-based, mixed-binary chiral sorbent grafted with the macrocyclic antibiotic eremomycin and bovine serum albumin (BSA) was obtained. The sorbent-filled high-performance liquid chromatography column was capable of enantioseparation of racemic drugs, such as profens, in reversed-phase-chromatography mode. The mixed-binary eremomycin-BSA-sorbent showed better capability for profens enantioseparation as compared with a sorbent containing eremomycin only. BSA grafted onto the sorbent surface significantly reduced retention times of other proteins from the analyte solution, and free proteins (including BSA) injected as analytes were not retained on the column, and subsequently eluted with a dead volume. The drastic difference observed in the binding of profens and other proteins using the sorbent was tested for determination and enantioseparation of profens in artificial-urine solutions.