Surface Of Glass Capillary Research Articles

Sensitive detection of ferbam by coupling solid phase microextraction with surface enhanced Raman spectroscopy based on Au nano-glass capillary

In this study, we developed an innovative approach that combines solid phase microextraction (SPME) with surface-enhanced Raman spectroscopy (SERS) to detect pesticide ferbam rapidly. An Au nano-glass capillary was fabricated by coating template-freely synthesized three-dimensional network Au nanostructures (3D-NW AuNSs) on the roughened surface of glass capillary and used for SPME and SERS respectively. Significant Raman signals were obtained by the SPME-SERS method, followed by detection of ferbam in water and orange juice samples with only 1 min SPME process. Results showed that Au nano-glass capillaries could achieve the detection of ferbam with limit of detection of 0.05 μg/L, and coefficient of determination (R2) of 0.9913. The recovery of predicted results was in the range of 88.46–103.29% and the relative standard deviation (RSD) was 3.5–8.2%. This study demonstrated potential capability of the SPME-SERS method for rapid (within 1 min) and sensitive detection of organic compounds in complex matrices. The SERS-active Au nano-glass capillary is easy to carry and operate, and is expected to play a role in the detection of trace pollutants.

Glass capillaries with TiO2 supported on inner wall as microchannel reactors

In this work, we have successfully immobilized TiO2 nanoparticles with small particle size and narrow size distribution on the inner surface of glass capillaries. By integrating the beneficial properties of nano-sized TiO2 particles with microreactors, the highly efficient catalytic system showed good performance in oxidation of dibenzothiophene (DBT) and photocatalytic discoloration of methyl orange (MO). The mean particle size and loading amount (Ti content: 0.21–2.81wt.%) are both controllable via the simple manufacturing procedure. The diameter varied from 6.8 to 20.8nm with the pH increased from 1.59 to 6.48 using ethanol as the solvent. Particles prepared by methanol showed the largest size (18.2nm) and broadest size distribution compared with those synthesized with ethanol and isopropanol. DBT was converted completely within 2.8min with an initial concentration of 20ppm, and 100% discoloration of MO was obtained after 40s. The highly efficient microreactor is easy to be integrated on a large scale, thus providing a highly promising alternative for a broad range of catalytic applications.

Gold film-catalysed benzannulation by microwave-assisted, continuous flow organic synthesis (MACOS).

Methodology has been developed for laying down a thin gold-on-silver film on the inner surface of glass capillaries for the purpose of catalysing benzannulation reactions. The cycloaddition precursors are flowed through these capillaries while the metal film is being heated to high temperatures using microwave irradiation. The transformation can be optimized rapidly, tolerates a wide number of functional groups, is highly regioselective, and proceeds in good to excellent conversion.

Study on the interfacial properties of viscous capillary flow of dilute acetic acid solutions of chitosan

The relative viscosities of acetic acid solutions of chitosan at varied temperatures were measured in a common glass capillary Ubbelohde viscometer in the range from dilute down to extremely dilute concentration. With the aid of the newly proposed theory related to the effect of solute adsorption on the relative viscosity measurement, the experimental data was analyzed, and some interesting parameters describing the interfacial properties of viscous capillary flow were deduced. The change of the conformation of the chitosan chains both free dissolved in solution and adsorbed on the glass capillary surface were discussed in detail. Furthermore, the morphologies of the adsorbed chitosan was also observed by AFM.

Gold‐Film‐Catalysed Hydrosilylation of Alkynes by Microwave‐Assisted, Continuous‐Flow Organic Synthesis (MACOS)

Thin gold films on the surface of glass capillaries have proven to be highly active catalysts for the rapid hydrosilylation of alkynes that are flowed through the reactor while being heated by microwave irradiation. The films are able to be reused at least five times with no loss of activity and with no detectable levels of gold showing up in the hydrosilylated products.

A viscometric study for adsorption of bovine serum albumin onto the inner surface of glass capillary

AbstractViscosities of aqueous solutions of bovine serum albumin (BSA) at different temperatures were carefully measured in a common glass capillary Ubbelohde viscometer in the concentration range from dilute down to extremely dilute concentration regions. The adsorption effect occurred in viscosity measurements were theoretically analyzed and discussed. The theory based on the Langmuir isotherms could adequately describe the existing data. The influence of temperature on the adsorption of BSA solution was discussed and a simple adsorption model was proposed. The conformational change of BSA macromolecules happened both in the bulk solution and on the inner surface of glass capillary. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Development and characterization of an open tubular column containing immobilized P-glycoprotein for rapid on-line screening for P-glycoprotein substrates

Cellular membranes from a cell line expressing P-glycoprotein (Pgp(+)) and from a cell line that does not express Pgp (Pgp(−)) were immobilized on the surface of glass capillaries ( 25 cm×100 μm i.d.) by non-covalent interactions using the avidin–biotin coupling system to create two open tubular columns, Pgp(+)-OT and Pgp(−)-OT. Frontal displacement chromatography on the Pgp(+)-OT demonstrated that the immobilized Pgp retained its ability to specifically bind the known Pgp substrates vinblastin and ketoconazole. The calculated affinities, expressed as K d, for vinblastin and ketoconazole were 97 nM and 12.1 μM, which were comparable with previously reported K d values of 37 nM and 8.6 μM, respectively. The results confirm that the Pgp(+)-OT can be used to quantitatively estimate binding affinities for the Pgp. Frontal displacement chromatography on the Pgp(−)-OT demonstrated that the immobilized membranes retained the ability to bind some Pgp substrates, but that the binding was not due to specific binding to Pgp. A cohort of compounds containing high affinity Pgp substrates (vinblastin, prazosin) and moderate-low affinity Pgp substrates (doxorubicin, verapamil, ketoconazole) and a non-substrate (nicotine) were chromatographed on the Pgp(+)-OT and Pgp(−)-OT using fast frontal analysis and mass spectrometric detection. The results demonstrated that when the retention on the Pgp(+)-OT was corrected by subtraction of the retention on the Pgp(−)-OT, the test compounds could be accurately sorted into high, moderate-low and non-substrate categories. The data from the study indicates that a single 30-min parallel chromatographic experiment can be used to rank a compound based upon its relative affinity for the immobilized Pgp.

A polytetrafluoroethylene capillary viscometer

A polytetrafluoroethylene(PTFE) capillary Ubbelohde viscometer was designed and constructed. The relative viscosities of aqueous solutions of a polyethylene oxide and a polyvinylpyrrolidone sample were carefully determined down to an extremely dilute concentration region. In comparison with the data obtained from the common glass capillary viscometer, slippage is believed to occur in the PTFE capillary due to its hydrophobic nature. While for the glass capillary viscometer, conventional viscous flow is operative and adsorption phenomena occur since both the solvent water and aqueous solution are wet and/or adsorbed onto the glass capillary surface due to the existence of hydroxyl groups on glass surface. The data were analyzed with a recently developed wall-effect theory and satisfactory results were obtained.

High-sensitivity assay for pesticide using a peroxidase as chemiluminescent label.

The application of a newly isolated transgenic tobacco peroxidase (TOP) as a chemiluminescent label for immunoassay purposes is described for the first time. The enzyme has been oxidized with m-periodate and subsequently coupled to the model compound 2,4-dichlorophenoxyacetic acid (2,4-D) using a carbodiimide method. As compared to the native horseradish peroxidase used in control experiments, the TOP enzyme showed significantly higher efficiency of coupling to the antigen and no loss of the specific activity was observed. The obtained 2,4-D-TOP conjugate demonstrated unique properties in chemiluminescent detection. The latter allowed the minimization of the conjugate concentration due to the superior chemiluminescent activity of the enzyme. A highly sensitive capillary chemiluminescent immunoassay using the 2,4-D-TOP conjugate as labeled competitor is reported. Direct competitive ELISA has been performed using a specific monoclonal antibody immobilized onto the sol-gel treated glass capillary surface. A modified photomultiplier tube with a special holder for a capillary was used for the resulting chemiluminescent signal detection. The typical standard calibration curve for the 2,4-D pesticide detection is linear between 30 pg and 500 ng/mL.

The wall effect on viscosity measurement of dilute aqueous solutions of polyethylene glycol and polyvinyl alcohol using a paraffin-coated capillary viscometer

The relative viscosities of aqueous solutions of a polyethylene glycol sample and a polyvinyl alcohol sample were measured in a viscometer, the capillary wall surface of which was coated with paraffin. The results were compared with the data obtained from the original non-coated viscometer. Slippage occurs in the former case due to the hydrophobic nature of paraffin, while in the latter case, conventional viscous flow operates since both the solvent water and solution either wet and/or are adsorbed on to the glass capillary surface of the viscometer. The experimental data were analyzed with the aid of the recently proposed theory of the effect of solute adsorption on relative viscosity measurements. The formula, accounting for the effect of solute adsorption of polymer solutions down to the extremely dilute concentration region, are also applicable to non-wetting polymer solutions in which solute adsorption is eliminated. The results obtained were compared and analyzed using the idea of extrapolation length of slip flow proposed by de Gennes PG. CR Acad Sci Paris 1979;288B:219. The extrapolation length could be evaluated unambiguously from the relative or reduced viscosity data for polymer solutions down to the extremely dilute concentration region.

Simple method for collecting volatile compounds from single insects and other point sources for gas chromatographic analysis

A simple method is described for trapping airborne volatile compounds in the ng range for their subsequent gas chromatographic-mass spectrometric analysis. Volatile compounds are trapped on the inner surface of glass capillaries. The trapped compounds are extracted by rinsing the capillaries with 2–3 μl of solvent, and the extracts are directly analysed. As examples, pheromones are analysed. The method may also be suitable for the collection of volatile compounds from other point sources.

Technique for etching glass capillaries simultaneously with the drawing of the tubes

A method is described for the etching of the inner surface of glass capillaries by methyl 2-chloro-1,1,2-trifluoroethyl ether vapour carried out simultaneously with the drawing of the capillary tube. The influence of the vapour concentration on the level of etching of the capillary surface and on column efficiency was studied with glasses having different chemical composition.

Glass capillary columns with liquid crystalline stationary phases for gas chromatography. The influence of the pretreatment of the inside tube wall

The importance of capillary columns prepared with a liquid crystalline stationary phase are increasing. It is known that the interaction of the liquid crystals molecules with the glass capillary wall may strongly influence selectivity and efficiency of the column. The paper reports on systematic investigations on the correlations between the pretreatment of the inside glass capillary surface, the chemical nature of the liquid crystal and the chromatographic properties of the columns obtained.

The deposition of bacterial cells from laminar flows onto solid surfaces

In a previous article, the authors proposed a simple model for the rate of removal of bacterial cells from solid surfaces by fluid shear. This Model has been extended to include the deposition of cells from a flowing suspension. The theory is compared to experimentally obtained data for the deposition of Bacillus cereus cells onto the surface of glass capillaries. The effect of a hydrophobic surface, siliconized glass, and the addition of an antifoam agent to the suspension is also investigated.

High resolution glass capillary columns with chemically bonded stationary phases: application to the gas chromatographic analysis of sterols and steroids in biological extracts

AbstractA new approach has been developed for the preparation of highly stable glass capillary columns using irreversible bonding of polysiloxane polymers to the glass surface. The general procedure involves (a) synthesis of reactive linear polysiloxanes from variously (alkyl, aryl) substituted dichlorosilanes through homologous or heterologous polymerization under alcaline aqueous conditions, and (b) covalent condensation of the polymers to a properly prepared glass capillary surface at high temperature. The principle has been first applied to the successful preparation of apolar gas chromatographic systems (methylpolysiloxanes), then extended to the obtention of polar systems (methyl phenyl polysiloxanes). The flexibility of the approach is demonstrated by the possibility of obtaining stationary phases of various and controlled polarity (i.e., extent of phenyl substitution), tailor‐made to a given analytical problem. These gas Chromatographic systems appear to be remarkably stable both with time and temperature up to 300 C and compare favorably to existing systems for their high resolution properties. These columns have been satisfactorily used in the last years for the analysis of sterols and steroids of biological origin and most extensively in the study of urinary steroid metabolite in humans under pathological conditions.

A new, generally applicable procedure for the preparation of glass capillary columns

A new procedure fo the preparation of the inner surface of glass capillaries for subsequent coating with organic liquids is presented. This procedure is based on the production of a layer of barium carbonate crystals, grown from nuclei on the glass surface. In comparison with other methods it has the following merits: it greatly reduces dependence on glasss type; it requires no difficult manipulations or materials; it gives high reproducibility and probability of success, producing almost neutral, thermostable columns with high resistance to rugh usage, with wide applicability, and showing good, though not the highest, separation efficiency. This procedure is recommended in order to assist the numerous laboratories that wish to make their own glass capillary columns, without, however, needing to spend many months or even years in becoming specialized in this field. A simple, quick and almost universal method of preparation is need to enable the bulk of their analytical problems to be handled. A detailed description of the basic procedure alone is given. Various refinements are feasible, for example to increase separation efficiency or to include acidic columns by first transforming barium carbonate into barium sulphate.

Surface treatment of glass capillaries for gas-chromatography

A simple method for the treatment of the surface of glass capillaries is described. The influence of silanisation is shown and discussed. Application possibilities are shown.

Capillary Depression in McLeod Gauges

The purpose of this report is to describe a source of the ambiguity in measuring a low pressure by using the McLeod gauge. It has been found that the capillary depression is obstructive of the accurate measurements in pressure. Particular attentions have been paid to the inner surface of glass capillary, because the reproducibility of the capillary depression strongly depends on the surface conditions of capillary.The computation, of which the results theoretically predict the shape of meniscus, has been carried out with a high-speed digital computor, IBM-7090, according to Eq. 4. A table capable of obtaining the capillary depression, the meniscus height, and the contact angle for fine capillaries of 4 to 0.1 mm in inside diameter, has been made. Consequently, it has become possible to separate the ambiguity due to the contact angle from that due to the surface tension as shown in Fig. 6.Comparing the observed values with this table, the following results have been revealed that : (1) All the observed values are in good agreement with the theoretical curves, independent of the capillary species, (2) The capillary depression is different depending on the glass species and the surface condition as shown in Fig. 6, (3) The contact angles are in 119°-130° for the untreated Pyrex capillary, being in 138°-160° for the Pyrex one roughened by Rosenberg's method, as in Fig. 6 and 7, (4) Tapping is effective of reducing the extent of capillary depression, and(5) The surface tension seems to be vatiable.