Rapid HPLC method for acetyl starch determination in blood

Summary Colloidal plasma substitutes of chemically modified starch are used in surgery and in emergency medicine. Acetyl starch (ACS) is a new plasma substitute based on an amylopectin acetic ester. Metabolic cleavage of the ACS ester substituents leads to improved degradation and elimination of infused polymer. To determine the metabolic fate of ACS a rapid LC-method for ACS quantitiation in blood samples was needed. For this purpose a size-exclusion chromatography (SEC) system with improved sensitivity is outlined using a refractive index detector. The limit of detection is 0.005 mg mL⁻¹. From 0.10–5.00 mg mL⁻¹ a linear relationship (correlation coefficient R=0,9999) between the RI signal and ACS concentration is obtained. Recoveries of ACS from blood plasma range 102.3–107.7% for ACS 200/0.5 (range 0.20–7.94 mg mL⁻¹) and 103.0–111.4% for ACS 200/0.7 (range 0.19–9.33 mg mL⁻¹). Only small differences between runs are obtained. In the inter assay test coeficients of variation of 1.8% and of 2.6% respectively are obtained for ACS 200/0.5 and ACS 200/0.7.     

A simple and effective method for the purification of californium from other elements

The distribution coefficients of californium and other elements between an anion exchange resin and alcohol solutions of nitric acid of different concentrations have been determined. An effective method is suggested for the purification of californium from other elements which are slightly adsorbed when Cf is concentrated on an anion exchanger from 0.5–1.0N solutions of nitric acid containing 95–90% alcohol; Cf is subsequently eluted with a 0.5N HNO₃ solution in 85% CH₃OH and simultaneously separated from the elements which are strongly adsorbed on the anion exchange resin. Under the chosen conditions the coefficients of californium purification were determined for a number of elements; the values are 5.4·10²–1.8·10³ for Al, Ca, Fe and ∼10³–10⁵ for Am, Pm, Nd, Ce, Pb, Bi and Na, for one cycle.     

Determination of Eprinomectin in Bovine Urine and Feces Using HPLC with Fluorescence Detection

Eprinomectin is a novel and potent antiparasitic animal health drug. An analytical procedure for the determination of EPR in bovine urine and feces has been developed. The urine sample was centrifuged and alkalized with ammonia following solid phase extraction. The fecal sample was extracted with acetonitrile, defatted with hexane, cleaned-up using C18 cartridge. All samples were analyzed by high performance liquid chromatography with fluorescence detection after derivatization with N-methylimidazole. The limits of detection are 0.5 ng mL⁻¹ and 0.5 ng g⁻¹, respectively. Fortified at 2, 10, 50, and 100 ng mL⁻¹(ng g⁻¹), inter-assay recoveries of EPR in cattle urine and feces were in the range of 87.9–91.5% and 78.6–86.3%, with coefficients of variation of 5.4–10.2% and 1.4–7.2%, respectively. Intra-assay mean recoveries of the analytes were 82.2–86.5% and 79.6–87.3%, with coefficients of variation of 7.8–11.5% and 6.3–7.8%, respectively. The method was used to study the excretion of eprinomectin in bovine urine and feces after subcutaneous administration at a dose of 0.5 mg kg⁻¹.     

Determination of triazine herbicides in human body fluids by solid-phase microextraction and capillary gas chromatography

Summary Eight triazine herbicides, prometon, propazine, atrazine, simazine, prometryn, ametryn, metribuzin, and cyanazine, have been extracted from human whole blood and urine samples by headspace solid-phase microextraction (SPME) with a polydimethylsiloxane-coated fiber and quantified by capillary gas chromatography with nitrogen-phosphorus detection. Extraction efficiencies for all compounds were 0.21–0.99% for whole blood, except for cyanazine (0.06%). For urine, the extraction efficiencies for prometon, propazine, atrazine, prometryn and ametryn were 13.6–38.1%, and those of simazine, metribuzin and cyanazine were 1.35–8.73%. The regression equations for the compounds extracted from whole blood were linear within the concentration ranged 0.01–1 μg (0.5 mL)⁻¹ for prometon, propazine, atrazine, prometryn, and ametryn, and 0.02–1 μg (0.5 mL)⁻¹ for simazine, metribuzin, and cyanazine. For urine, regression equations for all compounds were linear within the concentration range 0.005–0.25 μg mL⁻¹. Compound detection limits were 2.8–9.0 ng (0.5 mL)⁻¹ and 0.4–2.0 ng mL⁻¹ for whole blood and urine, respectively. The coefficients of within-day and day-to-day variation were satisfactory for all the compounds, and not greater than 10.3 and 14.2%, respectively. Data obtained from determination of atrazine in rat whole blood after oral administration of the compound are also presented.     

Reduction of metol on mechanically renewed metal electrodes

The electroreduction of metol on mechanically renewed metallic electrodes is studied by direct voltammetry with linear potential sweep. Reduction peaks of metol are found in a neutral supporting electrolyte (0.02–0.5 M Na₂SO₄) on nickel, silver, and mercury electrodes before the potential of hydrogen liberation from the supporting electrolyte. The shape and parameters of the cathodic peak depend on an electrode material, and also on the composition and pH of the supporting solution. A probable mechanism of the electroreduction of metol is proposed. The regeneration of nickel and silver electrodes by in situ mechanical cutting of a 0.5-μm surface layer provides good reproducibility of the value of peak current; it is proportional to the concentration of metol in the range 2 × 10⁻³–1.8 × 10⁻² M.     

Structure and spectral-optical characteristics of Se,Se/CdS,and Se/Cd<Subscript>0.5</Subscript>Zn<Subscript>0.5</Subscript>S nanoparticles,stabilized in polymer-containing media

A method was proposed for the production of colloidal nanoparticles of selenium stabilized by polymers and surfactants, and their structural and optical characteristics were studied. It was shown that during the deposition of CdS and Cd_0.5Zn_0.5S on the surface of the Se nanoparticles followed by dissolution of the selenium with sodium sulfite it is possible to obtain network “nanoframeworks” with size 30–50 nm, formed by CdS or Cd_0.5Zn_0.5S particles measuring 3–5 nm. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 24–29, January–February, 2007.     

A test method for determining water in organic solvents

A test procedure is developed for determining water in acetone, dioxane, isobutanol, ethanol, petroleum ether, and ethyl acetate in the ranges 0.5–12; 0.5–10; 0.5–8; 0.5–6, and 0.5–4 vol %, respectively. Determination is based on the measurement of the acidity of a solution obtained upon adding citric acid or sodium hydrogen sulfate to organic solvents using an indicator test strip containing Congo red. The relative standard deviation of the results of analysis is 0.05–0.1; the duration of analysis is about 30 min.     

Determination of The Oxygen Chemical Diffusion Coefficient in Perovskites by a Thermogravimetric Method

A thermogravimetric method has been used for the determination of the oxygen chemical diffusion coefficients in La_1–xSr_xMnO_3+δ; x=0; 0.05; 0.10; 0.15 (LSM). A temperature range of 700–1000°C was studied. The chemical diffusion coefficient varies between 1.6⋅10^–13 and 1.8⋅10^–10cm²s^–1 for the samples in the temperature range studied. The activation energy for oxygen chemical diffusion was determined to be 190–280 kJ mol^–1 for the LSM samples. The magnitude of the chemical diffusion coefficients of the LSM samples does not depend on the strontium site occupation factor. This revised version was published online in July 2006 with corrections to the Cover Date.     

Non-selectivity in the reaction of levoglucosenone with the sulfinyl allyl carbanion

Condensation of levoglucosenone with the carbanion ofrac-allyl phenyl sulfoxide, in contrast with reactions of this anion with the majority of other unsaturated ketones, proceeds without regio- or enantioselectivity to give a (1.0–1.8): 1 mixture of products of both 1,2- and 1,4-γ-addition of the allylic residue. Each product is a (1.2–1.6): 1 mixture of epimers at the asymmetric sulfur atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 157–159, January, 1999.     

Determination of thorium and uranium in activated concrete by inductively coupled plasma mass spectrometry after anion-exchange separation

A sensitive analytical method was established for the determination of Th and U in activated concrete samples. The method combines an anion-exchange separation step with an ICP-MS determination technique. In the ICP-MS measurement, a few μg mL^–1 of Al and Ca, a few ng mL^–1 of Mn, La, Ce, Nd and Pb and pg mL^–1 amounts of Li, Zr, Nb and Ba coexisting in the anion-exchange fraction of Th and U did not interfere. No adverse interference effects were observed in real sample analyses. The obtained detection limits (3σ, n = 10) of Th and U were 2.3 and 1.8 pg mL^–1, respectively. The analytical precisions for ca. 5 μg g^–1 Th and ca. 1 μg g^–1 U in real activated concrete samples were equally less than 7% RSD. The accuracies obtained by the analysis of GSJ rock standard samples were –18.1 to 0.4% for the Th determination and –14.0 to –5.7% for the U determination. The method uses the conventional absolute calibration curve. The internal standard calibration is unnecessary. Received: 14 March 1999 / Revised: 13 July 1999 / Accepted: 15 July 1999     

Simultaneous GC-MS quantitation of acids and sugars in the hydrolyzates of immunostimulant, water-soluble polysaccharides of basidiomycetes

Summary The simultaneous quantitation of acids and sugars as their trimethyl silyl (TMS) derivatives has been extended in order to identify and quantitate the simple acid and sugar constituents in the hydrolyzates of various immunostimulant, water-soluble polysaccharides obtained from various Basidiomycetes, such as Armillariella mellea, Auricularia auricula-judae, Coriolus versicolor, Flammulina velutipes, Fomes fomentarius, Ganoderma applanatum, Ganoderma lucidum, Pleurotus ostreatus, Schizophyllum commune, Trametes hirsuta. Optimum hydrolysis conditions, performed with 2 M trifluoroacetic acid (TFAA) for five hrs, proved the presence of several sugars and acids with maximum recovery. (i) the total sugar/sugar alcohol content of polysaccharides varied between 20- and 65% and consisted of arabitol (0.01–10.2%), arabinose (0.09–1.3%), ribose (0.2–1.8%), fucose (0.3–1.2%), mannitol (0.01–5.3%), sorbitol (0.01–0.05%), galactiol (0.04%), fructose (0.08–0.8%), galactose (0.9–29%), glucose (10–53%), uronic acids (0.14–3.7%), sucrose (0.03–2%), trehalose (0.2–1%), cellobiose (0.01–0.6%), maltose (0.2–1.9%), other disaccharides (0.2–8%). (ii) The total of acids varied from 1.5 to 30% including o-phosphoric (1.3–19%), malic (0.08–4.7%), citric (0.08–4.7%), isocitric; (3%) and C₁₆−C₁₈ fatty acids (1–6%).     

Effect of the alkyl chloride-to-aluminum molar ratio in the catalysts of dec-1-ene oligomerization on the product distribution and the chlorine content in the products

Dec-1-ene oligomerization in the presence of an aluminum—1-dodecyl chloride system was studied. A mixture of low-molecular-weight oligodecenes containing 25–40 wt.% dimers and 30–52 wt.% dec-1-ene trimers is formed at the molar ratios RCl/A1 = 0.5–1.5. The oligomerization was assumed to occur under the action of cationic active sites, which are formed during the reaction of 1-chlorodedecane with aluminum. At temperatures of 120–130°C and molar ratios RCl/A1 = 0.5–1.5 metallic aluminum completely dechlorinates 1-chlorododecane in a dec-1-ene medium. The character of the effect of highly dispersed Al and the RCl/A1 molar rato on the fractional composition and chlorine content in oligodecenes was revealed. The latter are formed by an aluminum—tert-butyl chloride system used in the industrial oligomerization of dec-1-ene. A mechanism of Al dissolution by alkyl chlorides with the simultaneous dechlorination of alkyl chloride and formation of cationic active sites in A1-RCl systems was proposed to explain the results obtained. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 661–665, March, 2008.     

Electrocatalytic activities of binary and ternary composite electrodes of Pd, nanocarbon and Ni for electro-oxidation of methanol in alkaline medium

Films of binary and ternary composites of Pd, nanocarbon (C), and Ni are obtained on glassy carbon electrodes and investigated as electrocatalysts for methanol oxidation (MOR) in alkaline medium. Results show that among the electrocatalysts investigated, the apparent electrocatalytic activity of the Pd-0.5%C electrode is the greatest and that it decreases with increasing percentage of C in the composite. The Pd-0.5%C composite electrode has approximately two times higher activity than that of Pd electrode for MOR under similar experimental conditions. Introduction of Ni (1–2%) into the active Pd-0.5%C catalyst somewhat declines the apparent electrocatalytic activity of the electrode. The onset potential for MOR is observed to be the greatest negative at the Pd-0.5%C composite electrode, which gets shifted towards noble side by 80–100 mV with addition of Ni (1–2%).     

Residue Analysis of Propionylbrassinolide in Fruit and Vegetables by GC–MS

A rapid and simple method for the determination of propionylbrassinolide residues in tomatoes, apples and grapes using GC–MS is reported. Samples were extracted with acetonitrile, and the extracts were analyzed without any further clean-up. The results showed good linearity (r ² > 0.99) with standard solutions over the concentration range of 0.5–50 mg L⁻¹. The LODs and LOQs of propionylbrassinolide were 0.15 and 0.5 mg kg⁻¹ in all samples. Recoveries were in the range of 81.9–111.2%, with corresponding RSDs of 4.6–12.9% for three fortified levels. Intra- and inter-day RSDs were in the ranges of 1.5–14.2% and 5.3–15.6%. It was demonstrated that the proposed method is simple and efficient, and particularly suitable for detecting propionylbrassinolide residues in fruit and vegetables.     

Evaluation of Native and Chemically Modified Sargassum glaucescens for Continuous Biosorption of Co(II)

In the present study, biosorption of stable cobalt was studied in an up-flow fixed-bed column using the brown alga Sargassum glaucescens treated with formaldehyde (FA) or MgCl₂. Notable increase in cobalt removal was observed for FA-treated biosorbent with 2.7 and 1.4 times higher dynamic capacity (DC) and uptake capacity (UC) than native alga, respectively. Consequently, FA-treated S. glaucescens was selected for further investigations. In particle size experiments, the DCs of 0.5–1 and 1–2 mm particles were both equal to 27.6 mg/g, and corresponding UCs were 34 and 38 mg/g, respectively. The maximum DC was obtained at residence time of 2.5 min. Studying the effect of additional ions indicated partial effect of Na⁺ and K⁺ ions on DC and UC, Mg²⁺ reduced highly the DC and slightly the UC while heavy metal ions (Ni²⁺, Cd²⁺, Cu²⁺, Zn²⁺, Pb²⁺ and Cr³⁺) caused decrease in both DC and UC about 1.5–4.7 and 1.8–3.2 times, respectively. Moreover, the column regeneration studies were carried out for four sorption–desorption cycles. The DC and the UC highly decreased in the second cycle, partially decreased or remained constant in the third and in the fourth one.     

Silica covered porphyrin microstructures obtained in sol–gel processes

In this article, we report on the formation of well-defined highly emissive silica-covered porphyrin microstructures in base-catalyzed sol–gel processes. The microstructures were obtained by self-assembly of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (mTHPP) at room temperature. Tetraethoxysilane (TEOS) was used as a silica precursor. The hybrid mTHPP- silica particles were characterized by means of reflectance UV–Vis and microscopy techniques including atomic force microscopy, scanning electron microscopy (SEM) and confocal fluorescence microscopy (CM). The SEM and TEM observations revealed that depending on the porphyrin concentration used in the synthesis, the shape of the hybrid mTHPP-silica particles has changed from ribbon-like (c _mTHPP = 2.09 mM) to rhombus-like structures (c _mTHPP = 4.35 mM). The ribbons were straight-edged, uniform in width (1.2–1.8 μm) and height (350–400 nm), and variable in length (40–100 μm). The rhombs were 1–3.7 μm in height, 7–25 μm in length, and 3.5–15 μm in width, and the ratio of length to width was uniform and equal to ca. 1.8–2. UV–Vis absorption spectra indicated that the J-aggregates and H-aggregates formed in the systems with lower and higher porphyrin content, respectively. Formation of different type of porphyrin aggregates in both systems resulted in different emission spectra, as it was shown with CM.     

Covalent modification of glassy carbon electrodes with glycine for voltammetric separation of dopamine and ascorbic acid

Glycine was covalently grafted on to a glassy carbon electrode (GCE) by amine cation radical formation in electrooxidation of the amino-containing compound. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry proved the immobilization of glycine on the GCE. The modified electrode reduced the overpotentials of dopamine (DA) and ascorbic acid (AA) by approximately 0.15 V and 0.23 V, respectively, and resolved the overlapping voltammetric response of DA and AA into two well-defined voltammetric peaks in cyclic voltammetry (CV) or differential pulse voltammetry (DPV), unlike the unmodified GCE; this can be used for the simultaneous determination of these species in a mixture. The differential pulse peak current was linearly dependent on DA and AA concentration in the range 5 × 10^–6– 8 × 10^–4 mol L^–1 and 6 × 10^–5– 4 × 10^–3 mol L^–1, with correlation coefficients of 0.996 and 0.994, respectively. The detection limits (3δ) for DA and AA were 1.8 × 10^–6 mol L^–1 and 2.1 × 10^–5 mol L^–1, respectively. The modified electrode is very sensitive, selective and stable, and has been applied to the determination of DA and AA simultaneously in samples with satisfactory results. Received: 30 October 2000 / Revised: 9 March 2001 / Accepted: 13 March 2001     

Resonance light-scattering method for the determination of BSA and HSA with sodium dodecyl benzene sulfonate or sodium lauryl sulfate

A new resonance light-scattering (RLS) assay of proteins such as bovine serum albumin (BSA) and human serum albumin (HSA) is presented. In the medium of phosphoric acid (pH=2.6), the weak RLS of sodium dodecyl benzene sulfonate (SDBS) or sodium lauryl sulfate (SLS) can be greatly enhanced by proteins, owing to interaction between the protein and the anionic surfactant and formation of an associate. The RLS intensity of the SDBS–protein system is stronger than that of the SLS–protein system under same experimental conditions. It is considered that the synergistic resonance caused by the absorption of both protein and SDBS could produce strong RLS, while absorption of protein only in the SLS system could cause relatively weak RLS. The enhanced intensity of RLS is proportional to the concentration of the protein. If SDBS is used as the probe the linear range is 7.5×10^–9–1.5×10^–5 g mL^–1 for BSA and 1.0×10^–8–1.0×10^–5 g mL^–1 for HSA. The detection limits are 1.8 and 2.8 ng mL^–1, respectively. When SLS is used as the probe the linear range is 2.0×10^–8–1.0×10^–5 g mL^–1 and 2.5×10^–8–1.0×10^–5 g mL^–1 for BSA and HSA, respectively, and the detection limits are 12.8 and 21.6 ng mL^–1, respectively. The biological mimics samples are synthetic concoctions of BSA and HSA with some interferents. In these samples, the concentration of interferents is higher than the concentration normally existing in organisms. The samples were determined satisfactorily.     

A neutral polysaccharide from <Emphasis Type="Italic">Glycyrrhiza inflata</Emphasis>

A neutral polysaccharide Gi-A1 was isolated from the roots of Glycyrrhiza inflata Bat. It had a molecular mass of over 2000 kDa and showed [α]_D²⁰ + 81.4° (c 1.05, H₂O). Acid hydrolysis and methylation analysis indicated that Gi-A1 was mainly composed of α-D-glucose, α-L-arabinose, and α-D-galactose with a molar ratio of 8.0:1.8:1.0. It can significantly stimulate spleen cell proliferation in vitro (P < 0.01). Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 13–14, January–February, 2009.     

LC Determination of Four Isoflavone Aglycones in Red Clover (Trifolium pratense L.)

Red clover (Trifolium pratense L.) is an important forage plant that contains the isoflavones daidzein, genistein, formononetin, and biochanin A. These compounds have been studied lately due to their human health benefits. The aim of this study was to develop and validate an HPLC method with simplified sample preparation to quantify daidzein, genistein, formononetin and biochanin A simultaneously in red clover leaves. The validation showed that the method is specific, accurate, precise and robust, not to mention that the sample preparation is easier and faster than those described earlier. The response was linear over a range of 0.01–0.2 μg mL⁻¹ for daidzein, 0.05–0.5 μg mL⁻¹ for genistein, 4–40 μg mL⁻¹ for formononetin and 2–20 μg mL⁻¹ for biochanin A. The range of recoveries was 85.6–101.0%. The RSD for intra- and inter-day precision were <2.54 and <7.22%, respectively. Five populations of red clover, from the National Plant Germplasm System-USDA were analyzed and the content of daidzein, genistein, formononetin and biochanin A ranged from 7.87–91.31, 51.60–131.30, 6568.33–23461.82, to 2499.55–10337.33 μg g⁻¹ of dried material, respectively.