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  • 1
    Electronic Resource
    Electronic Resource
    The effect of an organic eluent modifier and pH on the separation of wheat-storage proteins: Application to the purification of γ-gliadins ofTriticum monococcum L (1989)
    Springer
    Chromatographia 28 (1989), S. 133-138 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Wheat proteins ; γ-gliadins ; Effect of pH on separation ; Effect of organic modifier on separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase, high-pressure liquid chromatography has been used to separate similar protein (γ-gliadin) components from 70% ethanol extracts of endosperm flour from two different accessions of the diploid wheatTriticum monococcum L. The effect of acetonitrile as the organic eluent was compared to acetonitrile: 2-propanol (3:1) at two different pH's. Conditions for maximum resolution of the γ-gliadin components were found to be at pH 7.2 with acetonitrile: 2-propanol (3:1) as the eluent. These conditions allowed the components to be obtained in sufficient purity for further charaterization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319634
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  • 2
    Electronic Resource
    Electronic Resource
    Development of a universal Raman detector for microchromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 257-262 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microchromatography ; Raman spectroscopy ; Deuterated solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detector for microchromatography in which Raman spectroscopy is used to identify the eluted species has been developed. The detector is designed to be applicable to a wide range of compounds without requiring the presence of a chromophore. Its use is illustrated in the analysis of nitro compounds on a 250 μm i.d. column. Raman spectra of each of the compounds could be identified as they passed the detector. The advatages of the use of fully deuterated solvents are demonstrated by the analysis of nitrobenzenes in methanol/water mobile phases. The detection limit for nitrobenzene using the Raman line at 1342 cm−1 was 75ng.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466391
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  • 3
    Electronic Resource
    Electronic Resource
    A particle size distribution analysis of used HPLC column packing material (1993)
    Springer
    Chromatographia 35 (1993), S. 295-301 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Used column packings ; Particle size distribution ; Scanning electron microscopy ; Column age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Particle size distribution analysis and scanning electron microscopy (SEM) were carried out on eight used HPLC columns containing either irregular silica based, spherical silica based or spherical polymer based packing material. Particle size distributions of the used irregular silica based columns were at least bimodat at the outlet ends and either biomodal or log-normal at the inlet ends with regular progressions between the two extremes through the column. A new ODS-3 column showed log-normal size distributions from the inlet to the outlet ends. Spherical silica based column particle size distributions showed distinct shoulders on large central distribution peaks in most column sections with various degrees of shoulder erosion. The spherical resin based column showed a broader inlet particle size distribution progressing to a very narrow outlet distribution. SEMs of both irregular and spherical silica based columns revealed a larger number of undersized particles and debris at the outlet than inlet ends which could have resulted from stationary phase degradation, since this was not seen in the new ODS-3 column. While several SEMs of the spherical silica based columns revealed hollow spheres and twins, the spherical resin based column packing showed stress fractures or wrinkle lines resulting from use or dehydration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277513
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  • 4
    Electronic Resource
    Electronic Resource
    Time optimization for routine separations, using high-speed microbore HPLC (1985)
    Springer
    Chromatographia 20 (1985), S. 87-96 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02280603
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  • 5
    Electronic Resource
    Electronic Resource
    The case of the elusive tm values in HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 156-158 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mobile phase retention time ; Capacity factor ; Negative capacity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Numerous ideas and procedures have been suggested in the literature for the determination of tm, the retention time of a non-retained species, in high-performance liquid chromatography. In some cases chromatograms have been obtained showing sample components eluting prior to the assumed non-retained species. This phenomenon results in apparent negative capacity factors for the species in question. We have proposed a method employing small inorganic anions which results in a limiting value for tm and eliminates apparent negative capacity factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265868
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  • 6
    Electronic Resource
    Electronic Resource
    Catalytic hydrogenation of benzo(a) and benzo(e) pyrenes. Analysis of the hydrogenated products by charge transfer chromatography and HPLC on amino bonded phase (1990)
    Springer
    Chromatographia 30 (1990), S. 24-34 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Charge transfer separations ; Hydrogenated polycyclic aromatics ; Coal liquefaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hydroaromatics (partially hydrogenated polycyclic aromatic hydrocarbons) generated in the course of the process play an important role in the catalytic hydroliquefaction of coal. A difficult analytical task is to identify and to quantify these hydroaromatics among the preponderant polycyclic aromatic hydrocarbons. Generally speaking, the method carried out uses the specific separation of hydroaromatic by charge transfer chromatography. Structural identification is effected by using gas chromatography, alone or coupled with mass spectrometry, and HPLC on amino bonded phase with UV detection. As an aid to obtaining the standard compounds that are essential in that work, this paper describes the application of the above analytical procedure to the catalytic hydrogenation products (RhCl3/NaBH4 and Pd/C) of benzo(a) and benzo(e)pyrenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02270444
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  • 7
    Electronic Resource
    Electronic Resource
    A particle size distribution analysis of stressed HPLC column packing material (1991)
    Springer
    Chromatographia 31 (1991), S. 362-366 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Particle size distribution ; Stationary phase stress ; Silica gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A particle size distribution analysis has been completed on three different HPLC column packing materials including silica gel (Si60) and two bonded phases (RP8 and RP18). The stationary phases were subjected to 18 hours stress with 1 N or 3 N KOH and found to have quantitatively different distribution patterns initially, at 13 hours and finally at 18 hours although the average particle diameters for the Si60 and RP8 were the same or higher at 18 hours as initially. Thirteen hoursstress with sodium octanesulfonate, tetrabutylammonium phosphate and ammonium acetate at exaggerated conditions also resulted in distributional changes with the Si60 and RP8 decreasing in average particle diameter when exposed to ammonium acetate and tetrabutylammonium stressing respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262193
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  • 8
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatographic determination of furfural and hydroxymethylfurfural in apple juices and concentrates (1991)
    Springer
    Chromatographia 32 (1991), S. 45-48 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Furfural ; Hydroxymethylfurfural ; Apple juice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and sensitive method for determining 2-furaldehyde (FUR) and 5-hydroxymethyl-2-furaldehyde (HMF) in apple juices and juice concentrates has been developed. The method for FUR and HMF involves the solid-liquid extraction of the juice by using a C-18 cartridge prior to reversed-phase separation with detection at 280 nm. The mobile phase was acetonitrile-water (8/92, v/v) at a flow rate of 1.0 ml/min. Recoveries from apple juices and juice concentrates spiked at different levels ranged from 94.1 to 104.0 (FUR) and 94.5 to 100.5 (HMF). The quantification limit for both, FUR and HMF, was 5 ppb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262465
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  • 9
    Electronic Resource
    Electronic Resource
    Retention behavior of morphine and its metabolites on a porous graphitic carbon column (1998)
    Springer
    Chromatographia 47 (1998), S. 667-672 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous graphitic carbon ; Optimization ; Morphine and metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of a series of morphine-based opiates has been investigated using a porous graphitic carbon packing material at acid and alkaline pH. The effects of mobile phase pH, mobile phase organic percentage, column temperature and ionpairing agents were studied. All six opiates were separated within a close retention window despite large differences in measured lipophilicities of the individual opiates. The retention order was not related to the log P values of the opiates and strong retention of the fully ionised compounds was observed, particularly those with acidic functional groups. The effect of pH on the retention of the compounds indicated that the degree of ionisation of the individual compounds was important in the separation mechanism, suggesting that hydrophobic interactions were present in addition to the polar retentive effects observed above. The strong retention of the ionised glucuronide and sulphate conjugates of morphine is a particularly useful feature of the porous graphitic carbon packing material which has general applicability to the analysis of polar or ionised drug metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467451
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  • 10
    Electronic Resource
    Electronic Resource
    HPLC separation and relative quantitation of kaempferol glycosides in soybean (1988)
    Springer
    Chromatographia 25 (1988), S. 1049-1053 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Soyabean leaf extracts ; Kaempferol glycosides ; Kaempferol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method is described for the determination of kaempferol glycosides in soybean leaf extracts. The method is rapid and can provide qualitative and relative quantitative results for 9 kaempferol glycosides. The flavonol glycosides are extracted from soybean leaves by shaking the samples in 50% methanol; the extracts are filtered, evaporated to dryness and reconstituted in methanol before further purification through a C-18 Sep-Pak column. The samples are injected onto a C-18 HPLC column, separated by gradient elution with a 1% phosphoric acid: methanol mixture and detected on a UV/VIS diode-array detector. Flavonols were monitored at 265 and 348 nm and spectra from 180 to 400 nm were stored and used as an aid in identification. Relative quantities of the kaempferol glycosides among soybean cultivars were calculated from their proportion of peak area in the chromatograms. Total kaempferol concentration of the extracts was calculated after acid hydrolysis of the kaempferol glycosides to the aglycone and comparison of peak areas to kaempferol standards.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02259383
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