Vladimir N. Zaitsev

Publications (78) View all

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  Available from: Vladimir N. Zaitsev

  Article: Sorption of heteropoly acids on cellulose sorbents

  O.V. Zui, V.N. Zaitsev, S.A. Alekseev, V.V. Trachevsky
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  ABSTRACT: Sorption of heteropoly acids on the surfaces of cellulose and diethylaminoethylcellulose with molybdovanadophosphoric acid as an example has been studied by UV-VIS, infrared, and MAS-NMR spectroscopy. It has been shown that sorption of heteropoly acid on diethylaminoethylcellulose is substantially higher than that on ordinary cellulose. The mechanism of sorption includes combination of Coulomb and hydrophobic interactions. A scheme of heteropolyacids immobilization has been proposed based on ion exchange on cellulose surface.
  CHEMISTRY, PHYSICS AND TECHNOLOGY OF SURFACE. 01/2012; 3(1):66-73.
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  Available from: S. A. Alekseev

  Article: Chemically modified porous silicon for laser desorption/ionization mass spectrometry of ionic dyes.

  I V Shmigol, S A Alekseev, O Yu Lavrynenko, N S Vasylieva, V N Zaitsev, D Barbier, V A Pokrovsky
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  ABSTRACT: Desorption/ionization on silicon (DIOS) mass spectra of model ionic dyes methylene blue (MB+Cl-) and methyl orange (Na+MO-) were studied using p+ type-derived porous silicon (PS) free layers. As-prepared PS (PS-H), the PS thermally oxidized at 300 degrees C (PS-OX), PS with chemically grafted cation-exchanging alkylsulfonic acid (PS-SO(3)H) and anion-exchanging propyl-octadecyldimethylammonium chloride (PS-ODMA+Cl-) groups was tested as ionization platforms. Two mechanisms of the methylene blue desorption/ionization were found: (1) the formation of [MB + H]+* ion due to the reduction/protonation of MB+, which is predominant for PS-H and PS-OX platforms and (2) direct thermal desorption of the MB+ cation, prevailing for PS-SO3H. The fragmentation of the cation is significantly suppressed in the latter case. The samples of PS-SO3H and PS-ODMA+ Cl- efficiently adsorb the dyes of the opposite charge from their solutions via the ion-exchange. Consequent DIOS MS studies allow to detect only low fragmented ions (MB+ and MO-, respectively), demonstrating the potential of the ion-exchange adsorption combined with DIOS MS for the analysis of ionic organic compounds in solutions.
  Biological Mass Spectrometry 07/2009; 44(8):1234-40. · 3.41 Impact Factor
• Article: Organosilica composite for preconcentration of phenolic compounds from aqueous solutions.

  V N Zaitsev, V A Khalaf, G N Zaitseva
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  ABSTRACT: A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO(2)) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol) (TX). Under static conditions phenol was quantitatively extracted onto TX-SiO(2) in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO(2) for phenol is 2.4 mg g(-1) with distribution coefficients up to 3.4 x 10(4) mL g(-1); corresponding data for 1-naphthol are 1.5 mg g(-1) and 3 x 10(3) mL g(-1). The distribution coefficient does not change significantly for solution volumes of 0.025-0.5 L and adsorbent mass less than 0.03 g; 1-90 microg analyte can be easily eluted by 1-3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A(540)) and phenol concentration (C) in water was found according to the equation A(540) = (6 +/- 1) x 10(-2) + (0.9 +/- 0.1) C (micromol L(-1)) with a detection range from 1 x 10(-8) mol L(-1) (0.9 microL g(-1)) to 2 x 10(-7) mol L(-1) (19 microL g(-1)), a limit of quantification of 1 microL g(-1) (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical analysis. The detection limit of 1-naphthol with this method is 6 microL g(-1) while the quantification limit is 20 microL g(-1). A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08-3.2 mL g(-1).
  Analytical and Bioanalytical Chemistry 07/2008; 391(4):1335-42. · 3.78 Impact Factor
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  Available from: S. A. Alekseev

  Article: Covalent grafting of ion-exchanging groups on porous silicon for microsystem applications

  E. Méry, S.A. Alekseev, V.N. Zaitsev, D. Barbier
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  ABSTRACT: We report the chemical functionalization of porous silicon (PS) by trimethylammoniumpropyl bromide (–(CH2)3N(CH3)3+Br−) and alkylsulfonic acid (–CxH2xSO3H) groups for microsystem components. PS was prepared by electrochemical etching of a p-type silicon wafer. Samples of PS were first thermally oxidized at 300 °C and densified at 500 or 700 °C under an inert atmosphere. Mercaptopropyl and trimethylammoniumpropyl bromide groups were grafted on the PS surface via a silanization procedure. The oxidation of mercapto groups was used for the synthesis of –CxH2xSO3H groups. The samples were studied by Fourier transform infrared spectroscopy (FT-IR) and temperature-programmed desorption mass spectrometry (TPD-MS). The grafting of –CxH2xSO3H groups was found to be dependent on the densification treatment of the oxide layer formed at the surface of PS crystallites by low temperature oxidation. For PS samples thermally oxidized at 300 °C, –CxH2xSO3H were not grafted, whereas for PS samples oxidized and densified at 500 or 700 °C, they were successfully grafted. In opposite, the densification treatment of PS samples has no significant influence on the grafting of –(CH2)3N(CH3)3+Br− groups.
  Sensors and Actuators B: Chemical. 09/2007;
• Article: Probing of chemically modified silica surfaces by solvatochromic pyridinium N-phenolate betaine indicators

  I. V. Khristenko, Yu. V. Kholin, N. O. Mchedlov-Petrossyan, C. Reichardt, V. N. Zaitsev
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  ABSTRACT: The state of betaine indicators, 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate and 2,6-dichloro-4-(2,4,6-triphenylpyridinium-1-yl)phenolate, on the surfaces of aminosilicas, silica modified with aminodiphosphonic acid, and unmodified silica gel is studied with diffuse reflectance spectroscopy. The normalized polarity parameters are calculated for the surface layers of the sorbents. It is revealed that regions with substantially different polarity and acidity are present on the surface of chemically modified silicas.
  Colloid Journal 01/2006; 68(4):511-517. · 0.71 Impact Factor