Andrey A. Formanovsky

FIA-FAAS system including on-line solid phase extraction for the determination of palladium, platinum and rhodium in alloys and ores.

A number of aliphatic mono- and triamines have been investigated as potential reagents for solid phase extraction of Rh, Pd and Pt. Platinum group metals are recovered from hydrochloric acid solutions as ionic associates of their chloride complexes with protonated amines. The recovery of metals depends both on hydrophobic properties of amine and sorbent and on sorption behaviour of amine itself. For on-line solid phase extraction of platinum group metals 4-(n-octyl)diethylenetriamine and hyper cross-linked polystyrene sorbent SSPS have been applied. Quantitative recovery of rhodium and platinum in the form of their hexachloride complexes was achieved under non-equilibrium conditions of on-line dilution. Metals recovered are quantitatively eluted with 1 M hydrochloric acid solution in ethanol. A new FIA-FAAS method for the determination of Rh, Pd and Pt in solutions based on the decomposition of ores and alloys has been proposed. The RSD values are 0.03-0.08 at 50-ppb concentration level. The detection limits are 3-8 ppb for 1 min of preconcentration. The accuracy of the procedure was verified by the analysis of standard reference materials of sulfide ores and alloys.

Toward creating cell membrane glyco-landscapes with glycan lipid constructs

Synthetic glycolipid-like constructs dispersible in biological media and capable of incorporating into cell membranes have the ability to create novel artificial glyco-landscapes on living cells. Using a variety of different glycans ranging from disaccharides to polysaccharides, together with different lengths and high hydrophilicity spacers, we created a series of synthetic glycolipid-like constructs. Contacting these constructs with live cells gave modified cells with controlled glycan density and/or altered biological function. The ability to also use these constructs as solutions to inhibit antibodies, toxins, and virions extends the potential diagnostic and therapeutic uses for these synthetic glycolipid-like constructs.

Hapten design and development of polarization fluoroimmunoassay for nonylphenol

Polyclonal antibodies to nonylphenol (NP), raised against two different haptenic derivatives were characterized by a rapid, homogeneous polarization fluoroimmunoassay (PFIA). The first hapten, ω-(4-hydroxyphenyl)nonanoic acid (NP9), was designed to mimic the linear NP isomer and contains hydroxyphenyl and linear alkyl chain moieties of the NP molecule. The second hapten, 4-aminophenol (4AP), contains the hydroxyphenyl moiety of NP molecule alone and thus potentially mimics various phenolic compounds with different side chain structures. A number of fluorescent labeled antigens (tracers) with various structures of the spacer arm between the antigen and the fluorescent dye was synthesized and used to optimize the competitor structure for NP-specific PFIA. The most sensitive assay with limit of detection (LOD) and IC50 values of 8 and 53 mg L–1, respectively, was obtained when anti-NP9 antibody and NP9-labeled antigen were used. Anti-NP9 resulted in more specific assay, where the cross-reactivity toward the relative phenolic compounds did not exceed 5%. Anti-4AP displayed substantial recognition of several bis-substituted phenols, including 2-amino-4-chlorophenol and 2,4-dinitrophenol.

Detata-filters for metal preconcentration and multielement determination in natural waters

Abstract New sorption filters containing conformationally flexible aminc-carboxylic groups were proposed for preconcentration of metals. Quantitative recovery of metals was achieved in a dynamic regime at a solution flow rate up to 4 ml.min−1.cm−2 in a pH range 3–8 from solutions with high salt content and in the presence of natural complexing agents. The dynamic capacity of DETATA-filters of the heavy metals was investigated. XRF and ICP-AES methods of heavy metals determination after preconcentration on the filters were developed.

Sorption of palladium on hydrophobic polymers in the presence of alkylamines

Abstract Distribution ratios of palladium(II) between hydrochloric acid solutions and some non-polar sorbents in the presence of various reagents containing amino groups were determined. The sorption of palladium is caused by the formation of hydrophobic ionic associates of PdCl 4 2− anion with protonated amines. The recovery of palladium depends on the hydrophobic properties of ion associates and on the sorption behaviour of the amines themselves. The system involving hyper cross-linked polystyrene SSPS and 4- n -octyldiethylenetriamine was chosen for the on-line preconcentration of palladium. Conditions for the quantitative recovery and desorption of the metal were found. A FIA–FAAS method for the determination of palladium including on-line sorption preconcentration has been developed.

Synthesis of 2- and 3-pyridinyl(aryl)methanones

A procedure was developed for the preparation of 2- and 3-pyridinyl(aryl)methanones by the reactions of aryllithium with methyl pyridinecarboxylate and methyl esters of substituted phenylcarboxylic acids.

3-(4-Tolylazo)phenylboronic acid as the active component of polyhydroxy compounds-selective electrodes

Ionophoric, extraction, acidic and hydrophobic properties of 3-(4-tolylazo)phenylboronic acid (TAPBA) were studied. Determined Kd value equals to 36±2, pKa equals to 8.6±0.5. TAPBA extracts dobutamine from water into chloroform and transports it across a bulk chloroform membrane. The recovery is 83% (pH=7.5), the transport rate – (6.5±0.5)×10−7 mol/h. 1H and 13C NMR data confirm the formation of an 1:1 complex between arylboronic acid and catecholamine. TAPBA was used as electrode-active component of plasticized membrane electrodes with cationic and anionic responses to catecholamines and phenolic acids, respectively. For the diethyl sebacate-plasticized membrane, a slope of electrode function to dobutamine is 56±2 mV/decade; the detection limit is 1.3×10−5 mol/l; the linear range – 5×10−5–1×10−2 mol/l; the working pH-range – 4.8–7.6; the response time – 5–10 s. ISE gives incomplete cationic function to less lipophilic catecholamines. The membrane with cationic additive shows an anionic response to caffeic acid in wide pH range.

Fine Tuning of Pyrene Excimer Fluorescence in Molecular Beacons by Alteration of the Monomer Structure

Oligonucleotide probes labeled with pyrene pairs that form excimers have a number of applications in hybridization analysis of nucleic acids. A long excited state lifetime, large Stokes shift, and chemical stability make pyrene excimer an attractive fluorescent label. Here we report synthesis of chiral phosphoramidite building blocks based on (R)-4-amino-2,2-dimethylbutane-1,3-diol, easily available from an inexpensive d-(-)-pantolactone. 1-Pyreneacetamide, 1-pyrenecarboxamide, and DABCYL derivatives have been used in preparation of molecular beacon (MB) probes labeled with one or two pyrenes/quenchers. We observed significant difference in the excimer emission maxima (475-510 nm; Stokes shifts 125-160 nm or 7520-8960 cm-1) and excimer/monomer ratio (from 0.5 to 5.9) in fluorescence spectra depending on the structure and position of monomers in the pyrene pair. The pyrene excimer formed by two rigid 1-pyrenecarboxamide residues showed the brightest emission. This is consistent with molecular dynamics data on excimer stability. Increase of the excimer fluorescence for MBs after hybridization with DNA was up to 24-fold.

A novel trityl/acridine derivatization agent for analysis of thiols by (matrix-assisted)(nanowire-assisted)laser desorption/ionization and electrospray ionization mass spectrometry

The derivatization reagent was prepared in situ by the reaction of tris(2,6-dimethoxyphenyl)methylium hexafluorophosphate with N-(2-aminoethyl)maleimide and used for the modification of a number of low molecular weight thiols. The adducts were analyzed by (MA)(NA)LDI MS and ESI MS. All registered mass spectra ((MA)(NA)LDI, ESI) revealed intense peaks of the cations of the derivatization products. The increment of the derivatization agent (499 Da) shifts the ion peaks of analytes from noisy low mass regions, thus allowing the detection of low molecular weight thiols. LDI analysis of the natural-gas condensate sample showed the presence of saturated alkylthiols (up to C22H45SH).

The Total Large-Scale Synthesis of Argiopine

The total large-scale synthesis of a natural toxin argiopine, a polymethylenepolyamine derivative, was developed. It consisted of 26 stages and included three key block schemes. Most of the stages proceeded quantitatively, which excluded the necessity of using the chromatographic separation of intermediates.