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PubMed2004

Slurry sampling of sediments and coals for the determination of Sn by HG-GF AAS with retention in the graphite tube treated with Th or W as permanent modifiers.

A method for the determination of Sn in slurry samples of sediment and coal by hydride generation graphite furnace electrothermal atomic absorption spectrometry (HG-GF AAS) is proposed. The slurries were prepared by mixing the ground sample (particle size < or =50 microm) with 2.0 mol L(-1) HCl for the sediment samples or with 2.0 mol L(-1) HCl+1.0% v/v HF in a saturated boric acid medium for the coal samples. The slurry was placed in an ultrasonic bath for 30 min, before and after standing for 24 h, with occasional manual stirring. The graphite tube was treated with 0.5 mg of Th or W as a permanent modifier. Sn determination was carried out by electrothermal atomic absorption spectrometry at the optimized retention temperatures of 450 and 300 degrees C for Th and W treatment, respectively. With this coupling, kinetic interference in the formation of the hydrides is avoided, and excellent detection limits can be obtained by using peak height. For the chemical vapor generation device, an optimized volume of 2 mL of sample slurry and an optimized NaBH4 concentration of 5% m/v were employed. The vapor produced was transported and retained on the graphite tube surface, which was further heated for Sn atomization. The accuracy of the method was verified by analyzing five certified sediments and three coals. By using the external calibration against aqueous standard solutions, the results obtained were in agreement with the certified values only for the sediment samples. For the coal samples, an addition calibration curve, obtained for one certified coal, was necessary to achieve accurate results. The obtained limits of detection were 0.03 microg g(-1) for sediment and 0.09 microg g(-1) for coal with Th as permanent modifier. The relative standard deviations were lower than 15%, demonstrating an adequate precision for slurry analysis. Sediment and coal samples from Santa Catarina, Brazil, were also analyzed.

Journal Article↗
PubMed2005

Air handling in clean laboratory environments: the reason for anomalously high boron background levels.

The isotopic analysis of boron from material that carries only trace amounts of boron requires low boron blank levels. Large efforts are taken to keep blank levels low by purifying reagents. We performed exposure experiments and determined procedure blanks before and after the air-handling system was modified from silicate glass filters to polyethylene/polystyrole and active carbon filters. Our investigations demonstrate that the air-handling system may be the major source of boron blank in many laboratories, as the widely used silicate glass filters, which contain boron as a major component, in the form of borax and boric acid, release significant amounts of boron to the air.

Journal Article↗
PubMed2000

Capillary electrophoretic determination of dithiocarbamates and ethyl xanthate.

A simple and sensitive capillary electrophoretic method was developed for the separation and determination of sodium methyldithiocarbamate (metham), manganese ethylenebisdithiocarbamate (maneb) and ethyl xanthate in boric acid buffer by direct UV absorbance detection at lambda = 254 nm. The separation is dependent on pH and nature of the buffer. The detection limits (S/N = 3) are 1.7 x 10(-6) mol/L for ethyl xanthate, 1.3 x 10(-6) mol/L for metham and 2.1 x 10(-6) mol/L for maneb. The method has been successfully applied to the analysis of wheat samples spiked with maneb and in a commercial sample.

Anti-Infective Agents↗
PubMed2001

Direct determination of silicon in powdered aluminium oxide by use of slurry sampling with in situ fusion graphite-furnace atomic-absorption spectrometry.

A direct method for determination of silicon in powdered high-purity aluminium oxide samples, by slurry sampling with in situ fusion graphite-furnace atomic-absorption spectrometry (GF-AAS), has been established. A slurry sample was prepared by 10-min ultrasonication of a powdered sample in an aqueous solution containing both sodium carbonate and boric acid as a mixed flux. An appropriate portion of the slurry was introduced into a pyrolytic graphite furnace equipped with a platform. Silicon compounds to be determined and aluminium oxide were fused by the in situ fusion process with the flux in the furnace under optimized heating conditions, and the silicon absorbance was then measured directly. The calibration curve was prepared by use of a silicon standard solution containing the same concentration of the flux as the slurry sample. The accuracy of the proposed method was confirmed by analysis of certified reference materials. The proposed method gave statistically accurate values at the 95% confidence level. The detection limit was 3.3 microg g(-1) in solid samples, when 300 mg/20 mL slurry was prepared and a 10 microL portion of the slurry was measured. The precision of the determination (RSD for more than four separate determinations) was 14% and 2%, respectively, for levels of 10 and 100 microg g(-1) silicon in aluminium oxide.

Aluminum Oxide↗
PubMed2004

Boron uptake by ectomycorrhizas of silver birch.

Boron (B) is an essential micronutrient for plants but it is thought not to be essential for fungi. We studied whether the extraradical mycelia of Paxillus involutus in symbiosis with silver birch (Betula pendula) take up B and transport it to the host plant. We grew mycorrhizal plants in flat microcosms with a partitioning wall, below which there was only extraradical mycelium. A boric acid solution enriched in 10B was applied to these mycelia. Increased 10B/11B isotope ratios were subsequently measured in birch leaves, stems, and roots plus mycorrhizas in the upper compartment. Boron was therefore taken up by the mycorrhizal mycelia and transported to the host plant in this species combination.

Basidiomycota↗
PubMed2006

Immobilization of permeabilized whole cell penicillin G acylase from Alcaligenes faecalis using pore matrix crosslinked with glutaraldehyde.

The activity of penicillin G acylase from Alcaligenes faecalis increased 7.5-fold when cells were permeabilized with 0.3% (w/v) CTAB. The treated cells were entrapped by polyvinyl alcohol crosslinked with boric acid, and crosslinked with 2% (v/v) glutaraldehyde to increase the stability. The conversion yield of penicillin G to 6-aminopenicillanic acid was 75% by immobilized system in batch reaction. No activity was lost after 15 cycles and about 65% enzyme activity was retained at the end of the 31th cycle.

Cell Culture Techniques↗
PubMed1995

Chronic fungal vaginitis: the value of cultures.

OBJECTIVE: Our purpose was to examine the importance of fungal cultures in evaluating patients with symptoms of chronic vaginitis by assessing the relative contribution of various yeast species and by comparing infections caused by Candida albicans with those caused by other species. STUDY DESIGN: A prospective observational study of patients referred with chronic vaginal symptoms was undertaken. In addition to a standard evaluation of symptoms, cultures for yeast were performed on modified Sabouraud agar plates. RESULTS: Seventy-seven isolates were obtained from 74 patients. A total of 68% were Candida albicans; 32% were other species. The clinical syndromes caused by non-Candida albicans isolates were indistinguishable from Candida albicans infections. Fluconazole gave a short-term mycologic cure in all Candida albicans but only 25% of non-Candida albicans cases (p < 0.001). In non-Candida albicans infections, boric acid suppositories achieved the best mycologic cure rate (85%). CONCLUSION: Because non-Candida albicans species are responsible for a significant number of chronic fungal vaginal infections and are more resistant to therapy with fluconazole, fungal cultures are a valuable aid in confirming the diagnosis and selecting appropriate therapy.

Candida↗
PubMed1977

Benzalkonium chloride toxicity to the human cornea.

A 36-year-old woman fitted with a soft contact lens after an uneventful extracapsular cataract extraction was wearing her aphakic lens successfully until she switched her lens-soaking solution to an isotonic solution of boric acid, potassium chloride, and sodium carbonate preserved with benzalkonium chloride and edetic acid. After three days her eye became inflamed and vision decreased. No endothelial damage was apparent and the anterior chamber showed 2+ cell and flare reaction. Three weeks after removal of the lens and fitting with an aphakic lens visual acuity was 6/9 (20/30). Study of the preservative by a semiquantitative dilution method together with the clinical evidence in this case proved the cytotoxic effect of benzolkonium chloride when used to sterilize soft contact lenses.

Adult↗
PubMed1990

Large-scale preparation and characterization of N-linked glycopeptides from bovine fetuin.

A preparative scheme has been developed to purify asialo-glycopeptides from each of the three N-linkage sites of bovine fetuin, allowing the isolation of 100-mumols quantities of asialo-glycopeptides from 20 g of fetuin. The procedure yields seven asialo-glycopeptides which were determined to be 95% homogenous in peptide and oligosaccharide structure. The isolation scheme uses two high-capacity reverse-phase eluant systems. The primary RP-HPLC purification performed with boric acid buffered to pH 7 with triethylamine resolved sialylated tryptic glycopeptides simultaneously on the basis of glycosylation site and degree of sialylation. A second RP-HPLC purification was performed eluting isocratically with dilute phosphoric acid which resolved residual peptide and oligosaccharide heterogeneity from asialo-glycopeptides containing short peptides. Structural characterization of the products was performed utilizing 400-MHz proton NMR spectroscopy and amino acid and monosaccharide analysis. The glycopeptides contain two previously identified variant triantennary oligosaccharides which possess either Gal beta(1----4) or Gal beta(1----3) linkages to N-acetylglucosamine at one terminal branch or a biantennary oligosaccharide. These compounds should prove to be invaluable in studying carbohydrate-protein interactions, such as binding by the Gal/GalNAc lectin of mammalian hepatocytes, in the detailed three-dimensional structural analysis of complex oligosaccharides, and as purified substrates for the study of the action of glycoconjugate-modifying enzymes.

Animals↗
PubMed1977

[Thin-layer chromatography of sugars (author's transl)].

A thin-layer chromatographic method for the detection of sugars is described. The method can also be adapted for the use in biochemistry, pharmacology, and food chemistry. The solvent systems are: I, benzene/1-butanol/acetone/water (20 : 30 : 40 : 10, v/v); II, 1,2-dichloroethane/glacial acetic acid/methanol/water (50 : 25 : 15 : 10, v/v); III, boric acid 0.5%/1-butanol/2-propanol (20 : 30 : 50, v/v). Detection is developed by a diphenylamine aniline phosphoric acid reagent. Additionally an enzymatic method for the detection of some sugars is described.

Carbohydrates↗
PubMed1980

The real and apparent plasma oxalate.

A method for the determination of human plasma oxalate concentration by an enzymatic assay procedure is described using deproteinised plasma. The apparent concentration of oxalate in 20 normal subjects was 1.1--16.0 mumol/l (mean 7.78; S.D. 3.96). It was suspected that these results might be too high, due to the possible conversion of glyoxalate to oxalate, and this reaction was clearly demonstrated to occur in whole blood in vitro. Inhibitors (boric acid, DL-beta-phenyllactic acid, and allopurinol) of this oxidation were therefore added to the freshly taken blood samples, prior to assaying by the same technique. The plasma oxalate concentration from normal subjects was then found to be 0--5.4 mumol/l (mean 2.26; S.D. 1.67). It is concluded that normal blood spontaneously generates oxalate on standing, and the higher values obtained by other in vitro methods must be fallacious.

Blood Proteins↗
PubMed1984

Electrochemical detection of catecholamines in urine and plasma after separation with HPLC.

The catecholamines in plasma and urine were determined by electrochemical detection after separation on a HPLC column RCM 100 C 18. Linear calibration plots of epinephrine, norepinephrine and dopamine have been obtained in the range expected to appear in urine or plasma. Coefficients of variation (0.5 to 10%), recovery rates (60 to 80%) and the standard deviation were satisfactory, whereas plasma dopamine showed a greater variation (10-15%). The values ascertained by this technique were compared with those determined by the radioenzymatic assay of Da Prada et al. They showed a good correlation for norepinephrine r = 0.92, p less than 0.001 and epinephrine r = 0.80, p less than 0.01, but less for dopamine r = 0.1. Experimental details of isolation from plasma with Al2O3 adsorption and desorption with HClO4, and from urine with ion exchange chromatography on Bio-Rex 70 and elution with boric acid are described. Technical modifications which improve the method are reported. The optimized assay could reliably be employed in investigations of more than 3000 urine and plasma samples obtained from patients and athletes before and after exercise.

Chromatography, High Pressure Liquid↗
PubMed1993

Borate complexation of flavonoid-O-glycosides in capillary electrophoresis. II. Separation of flavonoid-3-O-glycosides differing in their sugar moiety.

Capillary electrophoresis was found to give significantly higher efficiency, selectivity and speed than high-performance liquid chromatography for the separation of a mixture of flavonoid-3-O-glycosides differing in their sugar moiety. Boric acid running buffer (0.2 M, pH 10.5) was used for this electrophoretic separation. The migration order in free solution capillary electrophoresis (CE) and the selectivity of these flavonoid-3-O-glycosides can be mainly explained by in situ borate complexation of both the sugar moiety and the cis-1,2-hydroxyl groups on the flavonoid skeleton and, to a lesser extent, by the ionization of hydroxyl groups on the flavonoid skeleton due to alkaline pH conditions. The correlation of the electrophoretic mobilities with the configuration and conformation of the compounds is discussed.

Anions↗
PubMed1975

Electroimmunoquantitation of serum proteins cross-linked by glutaraldehyde.

Electroimmunoassay is a simple, rapid and accurate method for quantitating the serum proteins. By use of glutaraldehyde, intermolecular cross-linkage of immunoglobulins to albumin was effected. The conjugation resulted in increased electrophoretic mobility of the immunoglobulins without perceptible change in antigenic determinants. With a Tris-EDTA-boric acid buffer system, the cross-linked immunoglobulins migrated anodically in an electrical field. Six serum proteins from each of 20 samples were quantitated by electroimmunoassay, and the results correlated with values obtained by radial immunodiffusion.

Aldehydes↗
PubMed1982

Purification of acute phase anti-hepatitis A virus (HAV) IgM and development of an IgM solid-phase radioimmunoassay for the detection of HAV.

A simple two-step procedure for the purification of IgM from acute phase hepatitis A infected chimpanzee serum has been developed. The procedure involves the precipitation of the euglobulin fraction with boric acid and the fractionation of the resuspended material on Sephacryl S-300 (Pharmacia Fine Chemicals, Piscataway, NJ). The purified IgM was used to develop a solid-phase radioimmunoassay (SPRIA) in which IgM was used as capture antibody and iodinated IgM was used as a probe. This assay was compared with a conventional IgG-based SPRIA. The IgM-based assay resulted in a superior response (P/N) for the detection of antigen in crude preparations; however, endpoint analyses demonstrated similar sensitivities.

Acute Disease↗
PubMed1976

Separation of prostaglandins E2 and F2alpha from their pulmonary metabolites by thin-layer chromatography.

A simple thin-layer chromatographic system has been developed separate PGE2 and PGF2alpha from 13, 14-dihydro-PGF2alpha, and other pulmonary metabolites of prostaglandins. The separation is achieved on Kieselgel-60 F-254 plates impregnated with both silver nitrate and boric acid. The system should be of use in the purification and tentative identification of primary prostaglandin.

Chromatography, Thin Layer↗