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  • Column liquid chromatography
  • Springer  (34)
  • American Association for the Advancement of Science (AAAS)
  • American Association of Petroleum Geologists (AAPG)
  • American Geophysical Union (AGU)
  • Elsevier
  • 2015-2019
  • 1985-1989  (34)
  • 1955-1959
  • 1985  (34)
Collection
Publisher
  • Springer  (34)
  • American Association for the Advancement of Science (AAAS)
  • American Association of Petroleum Geologists (AAPG)
  • American Geophysical Union (AGU)
  • Elsevier
Years
  • 2015-2019
  • 1985-1989  (34)
  • 1955-1959
Year
  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase ; Codeine phosphate drug substance ; Opium alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid procedure for the evaluation of codeine phosphate drug substance derived from poppy straw or opium concentrate is described. The gradient HPLC procedure employs a pH 2.5 phosphate buffer, methanol and acetonitrile mobile phase at 40°C and a μBondapak C-18 column. Eight opium alkaloids, including the four major alkaloids, are separated from each other. The paper describes details of the assay procedure and presents data documenting the linearity, specificity, precision, and sensitivity of the method.
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; External variance determinations ; Column and system compatibility ; Microbore and fast LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The demand for faster, more economic and convenient high-efficiency LC analyses has led to the development of microbore and fast columns. However, to utilize their benefits, the low column dispersions produced by these new technologies necessitate low external variances in the total system. This paper describes the determination of the external variance of microbore, fast and conventional LC systems by a column method. Compatibility with the relevant column technologies is evaluated by a method involving the comparison of the external and column dispersions. Direct comparison of chromatograms of an 8-component mixture, on a set of columns of various diameters and lengths, shows the relative speed, economy and sensitivity obtainable in practice. The problem of reduced sample loadability is considered and the practical solution of peak compression illustrated.
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention prediction system ; UV multichannel detector ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention prediction system assisted by a micro-computer coupled with an UV multichannel detector has been investigated in the separation of polycyclic aromatic hydrocarbons. The method offered very precise identification of components in NBS-SRM-1647 sample without any standard reference substances. It has been proven that the system makes very precise, non-pollutive and convenient environmental analysis possible.
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  • 4
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    Chromatographia 20 (1985), S. 313-322 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Tetracyclines antibiotics ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of high-performance liquid chromatography (HPLC) for the identification and determination of tetracycline antibiotics is reviewed. HPLC chromatograms provide fast identification by retention time, tR, and precise quantitation by measurement of peak height or peak area. For separation of tetracycline compounds, most HPLC methods use reversed-phase C18 or C8 columns and UV detection. The HPLC solvent system should have a pH of about 6 to prevent steric changes in the tetracycline molecule. For accurate quantitation it is necessary to avoid tailing and this is accomplished by adding a zwitter ion to the solvent system. Methanol and acetonitrile are frequently used as organic modifiers in these solvent systems. In a single analysis, HPLC methods can be used to separate as many as nine or ten commercially used tetracycline compounds and to determine four to five tetracyclines in commercial tetracycline preparations or in biological fluids.
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Resolution of optical isomers ; Chiral column ; Pyrethroids ; Fenvalerate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the optical isomers of fenvalerate [cyano(3-phenoxyphenyl)methyl 2-(4-chlorophenyl)-3-methylbutyrate] has been carried out by high-performance liquid chromatography (HPLC) on a chiral column with (R)-N-3,5-dinitrobenzoyl-phenyl-glycine (DNBPG) covalently bonded on aminopropyl silica and eluted with mixtures of methanol, 2-propanol, and hexane. The system was applied to the analysis of Pydrin®, an emulsifiable concentrate formulation of fenvalerate, and to the residue analysis of fenvalerate in milk samples. For the analysis of Pydrin® the only requirement was the proper dilution of Pydrin® with hexane. For the analysis of residues in milk, fenvalerate was extracted with hexane after precipitating the milk proteins with acetonitrile and removing the precipitate by filtration; the hexane extract was concentrated to small volume and filtered before being analyzed by HPLC.
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  • 6
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    Chromatographia 20 (1985), S. 487-494 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Controlled-porosity glasses ; Boron-enriched glass surface ; Adsorptive properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Controlled-porosity glasses (CPG) are sieves for macromoleculars, very widely applied in chromatographic columns for the separation of polymers and biopolymers by means of size-exclusion chromatography (SEC) and affinity chromatography. This paper deals with the influence of the thermal treatment of CPG on the elution of polymers in SEC columns. The problem is examined for a few mobile phases and for glasses having different porosities. Additionally, the SEC results obtained are compared with the adsorption properties of the glases investigated.
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  • 7
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    Chromatographia 20 (1985), S. 587-590 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Sulfonate pairing ion ; Adsorption isotherms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention of positively and negatively charged and neutral solutes was studied in an aqueous phosphate buffer eluent, with constant inorganic-counterion concentration, on ODS-Hypersil stationary phase in the presence of various sulfonic acid ion-pairing reagents. The adsorption isotherms of the ion-pairing reagents d-camphor-10-sulfonic acid, sodium cyclohexylsulfamic acid and sodium alkylsulfonates (butyl-, hexyl- and octyl-) were determined by the breakthrough method.
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  • 8
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    Chromatographia 20 (1985), S. 615-617 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vitamin B2 in food ; Column switching ; Liquid-solid extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Vitamin B2 was enriched by liquid-solid extraction from large volumes of aqueous samples on a short precolumn. The enriched compounds were transferred onto an analytical reversed-phase column and separated by ion-pair chromatography. The equipment used provides the possibility of automation for routine analysis.
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  • 9
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Controlled-porosity glasses ; Chemically bonded phases ; Boron-glass surface enriched
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In the preparation of C18-bonded phases higher coverage densities were obtained using dimethylaminodimethyl-n-octadecylsilane than chlorodimethyl-n-octadecylsilane as the reagents. The HPLC results show the very high hydrophobicity of the materials obtained. The elution mechanism has been found to be independent of the coverage density on the boron-enriched glass surface in the range 2.3–4.0 μmol/m2.
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  • 10
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Direct injection of biological samples ; New quinitidine metabolites ; Deproteinisation on precolumn ; Column switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New quinidine metabolites, including 10,11-dihydrodiol quinidine N-oxide, 10,11-dihydrodiol quinidine and their glucuronides, were found in human urine. A quinidine monitoring HPLC method including these metabolites, is proposed by the direct injection of body fluid samples onto the precolumn for deproteinization followed by reverse phase separation in the analytical column with a column switching technique. The recovery of spiked quinidine and its metabolites in plasma was quantitative (98–102%) with good reproducibility (C.V.: 1.6–4.0%). Several clinical samples such as whole blood and urine were analyzed by the present method.
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  • 11
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Quantitative structure-retention relationships (QSRR) ; CNDO/2-MO Calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention data for 12 aromatic test solutes with functional groups of various polarities were studied on a wellcharacterized monomeric octadecyl stationary phase over a range of methanol/water compositions. CNDO calculations on the solute structures and regression analysis indicated that two terms, the total energy, ET, and the maximal difference of electron excess charge, Cd, correlated well with changes in retention as a function of methanol composition. This approach allowed for the non-empirical calculation of retention data for solutes with a range of polarities, overcoming previous deficiencies in the estimation of molecular polarity for non-homologous solutes based on total dipole moment.
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  • 12
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Weak cation-exchanger ; Styrene-divinylbenzene copolymer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A weak cation-exchanger for high-performance liquid chromatography is obtained by oxidation of either poly(methylstyrene-divinylbenzene) or of poly(chloromethylstyrene-divinylbenzene). Reaction conditions were optimised to yield an exchange capacity of about 4meqg−1 dry resin. The material was evaluated chromatographically as a function of pH, organic modifier, temperature and flow rate. A combination of ionexchange and hydrophobic interaction between the solutes and the packing material was observed. This could be used to provide more options for realising chromatographic separations. Some chromatograms of heterocyclic bases, nucleosides, nucleotides and amino acids are shown.
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  • 13
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    Chromatographia 20 (1985), S. 87-96 
    ISSN: 1612-1112
    Keywords: Time Optimization ; Column liquid chromatography ; Microbore ; Theophylline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Algorithms for the time optimization of an HPLC separation are presented. Resolution, column performance, extra-column variance, capacity factor, and column length are incorporated into these algorithms. Extracolumn variance for a high-speed microbore system (1 mm i. d. column) was assessed using 2nd moment variance and a non-linear extrapolation of tubing length to zero. Extra-column variance, as a function of flowrate, was incorporated into the reduced operating curve of column performance. The use of empirical correction factors for column reproducibility and homogeneity are suggested. Cutting to an optimum length did not degrade column performance. These algorithms were applied to the optimization of a microbore assay for theophylline, in a simple xanthine mixture. Resulting total analysis times were reduced to 10seconds per sample, at a flowrate of 700μl/min.
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  • 14
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metal complexes ; Tetrakis(4-methylphenyl)porphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The feasibility of reversed-phase high-performance liquid chromatography for the separation of several metal complexes ofmeso-tetrakis(p-tolyl)porphine (TTP) is described. A combination of an octadecyl-bonded stationary phase with a non-aqueous polar mobile phase, such as an acetone-acetonitrile mixture, has proved effective for the separation. Thus, the TTP complexes of Mg, VO, Ni, Cu, Zn, and Pd and also TTP free acid were successfully separated in about 10min on a Li-Chrosorb RP-18 column (7μm, 250×4mm i.d.) with a 70∶30 (vol/vol) mixture of acetone and acetonitrile at a flow-rate of 1 mlmin−1.
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  • 15
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    Chromatographia 20 (1985), S. 213-218 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nitro-PAHs ; Diesel particulate extract ; Column switching-HPLC ; Pyrene-butyric acid stationary phase ; π-acceptor ligands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of nitrated polynuclear aromatic hydrocarbons (nitro-PAHs), in particular 1-nitropyrene, in diesel particulate extracts. The method employs a multidimensional HPLC (column switching) technique with final on-line peak identification by UV-VIS spectral comparison with standards. To achieve exceptional chromatographic selectivity for nitro-PAHs, a new pyrene butyric acid amide phase has been prepared which is capable of forming donor-acceptor complexes with them. With this technique it is possible to confirm the presence of 1-nitropyrene in the range 3–100 ng/mg on filter-collected diesel soot. Its utility was demonstrated with diesel exhaust extracts spiked with varying levels of 1-nitropyrene and proved to be highly selective.
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  • 16
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microcapillary column ; Gasoline group analysis ; Conventional IR detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Slurry-packed microcapillary column liquid chromatography with conventional infrared detection is described for the group-type analysis of gasolines. The results indicate that the three eluted groups, saturates, olefins and aromatics, from the microcapillary column are easily detected by conventional microcomputerized infrared spectrometer coupled with a Teflon flow-cell with a good signal-to-noise ratio. This study shows the feasibility of microcapillary column liquid chromatography combined with a low-cost, conventional infrared spectrometer as a routine tool which allows the analyst to use an LC-IR system effectively and economically.
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  • 17
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    Chromatographia 20 (1985), S. 425-433 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Adsorption isotherm ; Dead volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In RPLC the dead volume can be defined as the difference between the maximum column hold-up volume and the volume of the adsorbed phase. The composition of the adsorbed phase depends on the composition of the mobile phase and therefore, the dead volume also varies with it. In this work, the alkyl bonded phase acetonitrile (ACN)-water mobile phase system is investigated. In the system, deuterated water (D2O) and deuterated acetonitrile (D-ACN) are retained due to the isotopic dilution effect. By means of D2O and D-ACN, the absolute adsorption isotherm of the organic modifier ACN is measured. Based on the isotherm, the chromatographic behaviour of ACN, D-ACN and D2O, the variation of the dead volume with the composition of the mobile phase, and the approach to determine the maximum column hold-up volumn are explained. In addition, the various approaches to determine the dead volume are compared and the recommendations are given for the case of common unbuffered binary systems (MeOH/H2O, THF/H2O and ACN/H2O).
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  • 18
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amiloride hydrochloride ; Hydrochlorothiazide ; Quantitative determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure for the simultaneous quantitative determination of amiloride hydrochloride and hydrochlorothiazide by high-performance liquid chromatography is proposed. A reversed-phase LiChrosorb C8 stationary phase is used. The eluent consisted of an acetonitrile/0.1M phosphate buffer pH3 (15∶85) mixture, containing 50mM propylamine hydrochloride. In this system amiloride hydrochloride, a basic drug, eluted with a acceptable asymmetry factor (Asf=2.1). A simple extraction procedure with methanol is used. Relative standard deviations of 0.87% and 1.6% were obtained for amiloride hydrochloride and hydrochlorothiazide respectively. Chlorothiazide, a thiazide diuretic, is a suitable internal standard. Furthermore the method is also specific for other thiazide diuretics, potassium-sparing diuretics and loop diuretics and for the respective hydrolysis productes of both drugs. Analysis time is reduced to a minimum; the chromatographic separation is complete within 6 minutes.
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  • 19
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    Chromatographia 20 (1985), S. 495-499 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; L-tryptophan-serum albumin binding ; Bovine serum albumin ; Human serum albumin ; Binding parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two high-performance liquid chromatography (HPLC) techniques were developed for the determination of binding constants in the interaction of serum albumin with L-tryptophan: internal calibration and external calibration. The results obtained were compared with those obtained by the classical method of equilibrium dialysis and by gel filtration. While all the methods are equally reliable, the internal and external calibration techniques seem to be superior in their simplicity, speed and convenience.
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  • 20
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    Chromatographia 20 (1985), S. 529-532 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Modified silica gels ; Pyrimidines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of the surface chemistry of bonded-phase column material containing alkyl, phenyl, cyano and amino groups on the adsorption of pyrimidine molecules has been studied by HPLC. The dependence of the retention on the chemical structure of the adsorbed molecules was determined. The influence of the substituents at the pyrimidine ring and their position on the retention character is shown for various bonded phases.
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  • 21
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    Chromatographia 20 (1985), S. 559-565 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reaction detector ; Formaldehyde determination ; Trace analysis ; Cosmetic products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of free formaldehyde in the presence of its donators in cosmetic samples by a combination of reversed phase chromatography and post column reaction detection is described. The free formaldehyde is separated on a RP column with water as eluent from interfering formaldehyde-containing compounds and consecutively determined by the lutidine method in a reaction detector with knitted open tubes. With detection in the visible (420nm) the minimum detectable quantity is 40 ppb, with fluorimetric detection 15 ppb. The sample clean-up procedure for cosmetic products ranging from mascara to shampoo is by extracting the formaldehyde with water of pH 3, where the decomposition rate of the donators is minimal. Smaller amounts of free formaldehyde are always found compared to the standard lutidine method.
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  • 22
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; FTIR detection ; Aqueous eluents ; Deuterated compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Deuterated compounds have been used as mobile phases for microcolumn high-performance liquid chromatography (HPLC) employing flow-cell Fourier transform infrared spectroscopy for detection. Separations were carried out on adsorption, reversed-phase, non-aqueous size-exclusion and aqueous size-exclusion chromatographic columns. Due to the IR transparency of deuterated compounds in a C−H stretching region they represent nearly ideal eluents in terms of universal detection. In addition, due to the shift in the absorption wavenumber following deuteration, deuterated solvents allow FTIR detection of solutes in other regions, where otherwise it would be prohibited, or sensitivity sacrified by interfering solvent absorption.
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  • 23
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention volumes ; ODS silica ; Aromatic compounds ; Substituent interaction effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention volumes of monosubstituted benzenes, benzoic acids, phenols and anilines have been measured in reversed-phase liquid chromatography. Buffered acetonitrile-water and tetrahydrofuran-water eluents were used with an octadecylsilylsilica adsorbent. From the net retention volumes a substituent interaction effect was calculated and described with the linear free energy relationship developed by Taft. The positive sign of the values of the ρ-parameters, figuring in this relationship, was interpreted in terms of hydrogen bonding between the solutes and the eluent.
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  • 24
    ISSN: 1612-1112
    Keywords: Donor-acceptor complexes ; Column liquid chromatography ; Caffeine bonded phase ; 7(n-propyl)theophylline silica ; Petroleum residues and asphalts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of a new caffeine phase for HPLC is described. The capacity ratios (k′) of about ten polyaromatic hydrocarbons have been determined. It has been shown that the aromatics were eluted according the number of rings, only slightly influenced by the substituents. The performance of the stationary phase is demonstrated with separations of petroleum asphalts and residues and aromatic mixtures.
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  • 25
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    Chromatographia 20 (1985), S. 179-184 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Potentiometric detection ; Copper electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A metallic copper electrode housed in a suitable flowcell is shown to be a sensitive and versatile potentiometric detector for ion chromatography. This electrode may be used for direct or indirect detection of many inorganic anions and cations and also for organic acids. In the direct detection mode, electrode response is based on either complexation of copper ions at the electrode surface by eluted species, or on oxidation and reduction reactions for eluted species which are strong oxidants or reductants. Direct detection is therefore applicable to such species as amino acids, organic acids, chloride, bromide, iodide, chlorate, bromate and iodate. Indirect detection is possible for anions which do not complex copper ions, provided a copper complexing ligand (such as phthalate) is used in the eluent; cations which complex this ligand are also detectable. Indirect detection may be used for species such as nitrite, nitrate, acetate, formate, succinate, benzoate, alkaline earth ions and transition metal ions. Electrode calibration relationships are discussed and sample separations are presented, together with some typical detection limits attainable in the direct and indirect detection modes.
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  • 26
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    Chromatographia 20 (1985), S. 239-241 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded phases ; Anthracene silica gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N(9-methylanthracene)aminopropyl silica gel is introduced as a new reversed-phase packing material. It has specific selectivity for some aromatic compounds. In this paper the anthracene phase is compared with commercial octadecyl-, phenyl- and aminopropyl-bonded silica gels.
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  • 27
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino silica gel ; Neuraminic acids ; UV detection at nanomole level
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Neuraminic acid derivatives were separated easily by liquid chromatography on amino phases and using acetonitrile/15 mM phosphate buffer, pH 5.2 as mobile phase. Detection at 200 nm allowed determination of substances in the nanomole range. All solvent systems were used isocratically at room temperature. The separation did not depend on ion-exchange but on a partition mechanism, the solutes being separated according to their polarity. Thus, it was possible to optimize the resolution by varying the stationary phase and the composition of the eluent.
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  • 28
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenyl bonded phases ; Effect of pore size on retention ; Polycyclic aromatic hydrocarbons ; Silica supports
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Differences in bonded phase properties were studied for triphenyl, diphenyl, phenyl and benzyl phases prepared on a variety of silicas. A total of six silicas with pore diameters ranging from 100 to 200 Å were used in the synthesis. The effect of the pore diameter of the silicas on the retention of polycyclic aromatic hydrocarbons are discussed. Differences in retention were observed as a function of pore size, but not much difference was observed with substrates having pore sizes larger than about 170Å. The observed phenomena are explained by two steric exclusion mechanisms, one during the bonding reaction, and the other in the chromatographic analysis. Statistical calculations were performed using the descriptors showing molecular size and/or shape. The results indicated that the difference between bulky phases and less bulky phases was only observed in the degree of shape-recognition ability of the solute while no differences exist in the retention mechanisms on the different phases.
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  • 29
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    Chromatographia 20 (1985), S. 303-307 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion ; Dynamic equilibrium ; Ion-pairing interaction ; Monomer-dimer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecular interaction between uni-uni valent ions and bovine serum albumin was investigated by size-exclusion chromatography. Elution profiles are first presented for salt and protein solutions as samples with water as the mobile phase; then for water and protein as samples with salt solutions as the mobile phase. The results suggest the existence of a dynamic equilibrium between the salt ions and the protein ions as reactants and the ion-pair (salt-protein) complex as a product.
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  • 30
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    Chromatographia 20 (1985), S. 471-476 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Organic polyselenides ; Molecular area effects ; Comparison with polysulphides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Organic polyselenides in which the selenium chains are terminated at both ends by ethyl-thio, butyl-thio, phenylthio, or phenyl groups were prepared. Their chromatographic behavior in HPLC on a bonded octadecyl phase with entirely or mainly methanolic eluents was investigated and compared with the corresponding polysulphides. The retention increment per Se atom is greater than that for S atoms. The ratio of Se to S increments is equal to the ratio of surface area increments. The S−Se bond does not have an appreciable influence on retention. Bonded to phenyl, selenium increases retention to the same extent as sulphur does. Some of the RSSenSR solutes were identified by mass spectrometry and other techniques.
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  • 31
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    Chromatographia 20 (1985), S. 13-19 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Open tubes ; Diffusion coefficient ; Calibration curve for oligostyrenes ; Diffusion-averaged molecular weight ; Polydispersity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The concept of a diffusion-averaged molecular weight, Md′ is presented, and Md is defined for polydisperse samples. It is shown via oligostyrene mixtures that Md can be determined in 20 minutes with common chromatographic equipment. If Md is measured and Mn or Mw is known, the polydispersity can be obtained.
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  • 32
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Silica gel solubility ; Copper (II) silica gel solubility ; Copper (II) silica gel stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary After summarizing published results on silica gel and alkyl-bonded silica gel solubilities, the experimental solubility of unmodified silica and copper silicate gel (used in ligand exchange chromatography) in watermethanol-ammonia and water-acetonitrile-ammonia mixtures are given. These results demonstrate that silica gel solubility, measured by a static method, varies greatly with the water volume fraction of a ternary mixture. Curiously, no influence from the organic nature of the solvent was demonstrated. This observation is inconsistent with the fact that the copper silicate gel used in ligand-exchange chromatography with water-methanol-ammonia as mobile phase is attacked more rapidly than with water-acetonitrile-ammonia. An explanation based upon the variations of acid-base properties of silicic acid versus mobile phase dielectric constant values in conjunction with the methanol protophilic properties is proposed. Finally, it is shown that chromatographic columns filled with copper silicate gel have lifetimes of several months, if they are used with a procolumn (of copper silicate gel) and with acetonitrile as organic solvent with a volume fraction greater than 0.5 in the mobile phase.
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  • 33
    ISSN: 1612-1112
    Keywords: Hydrolysis, high temperature ; Column liquid chromatography ; Ion-exchange ; Cellulose ; Oligomeric and monomeric sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The hydrolysis of different cotton materials under hydrothermal conditions was investigated. For the analysis of the resulting reaction products high-performance liquid chromatography and gel-permeation chromatography were applied. HPLC columns with ion exchange materials as stationary phases (HPX 87P and Shodex S801) enabled the separation of monomeric sugars and degradation products. Oligomeric sugars were analyzed using a gel column (Bio-Gel P-2) as well as a HPLC column (HPX 42A). Through identification of additional reaction products the mass balance of the hydrolysis can be improved and the analysis of the distribution of the oligomeric sugars gives information for the selection of the reaction conditions.
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  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 20 (1985), S. 96-98 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phthalic anhydride ; Naphthoquinones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple method of analysis of the 1,2 and 1,4 isomers of naphthoquinone in crude phthalic anhydride has been developed. The sample was first dissolved in water at 60°C to quantitatively hydrolyse the anhydride to phthalic acid. Analysis of the aqueous solution by reversed-phase HPLC using 75∶25 methanol:water mobile phase resulted in excellent resolution between the phthalic acid and the naphthoquinones and enabled quantitative measurement of each of the naphthoquinones to 0.1 % in crude phthalic anhydride.
    Type of Medium: Electronic Resource
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