摘要:

AbstractIndications that already in the Ancient World, methods based on chromatographic principles were utilized, are discussed. As pointed out, they had little to do with chromatography.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180502

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis work presents two techniques for testing for the adulteration of flavors. One uses multidimensional gas chromatography on cyclodextrin derivatives to separate chiral compounds, the other uses isotope ratio mass spectrometry coupled with gas chromatography to determine stable isotope ratios. Applications to fruits and plants for the food and perfume industry are introduced.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA method is described for the detection of citrus juices adulterated by addition of industrial sugar products. The oligosaccharides maltotriose (DP3) and maltotetraose (DP4), both of which are absent from the natural sugar profile of citrus fruits, serve as markers. The sample preparation method includes clean‐up on a solid phase ODS cartridge, fractionation of DP3 and DP4 carbohydrates by LC on aminopropyl silica gel, and derivatization of the collected sugars to form the oxime‐trimethylsilyl derivatives. Capillary GC analysis is performed on a 30 m × 0.32 mm i.d. polydimethylsiloxane fused silica column applying cool on‐column injection and FID detection. The detection limit for maltotriose and maltotetraose is about 1 mg l−1. Several orange and grapefruit juices were evaluated on their authenticity. Adulteration with crystalline sugar products cannot be detected with the described p

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractMaterials used in the manufacture of silicone breast prostheses were analyzed by supercritical fluid chromatography (SFC) and high temperature gas chromatography (GC) coupled with direct deposition FT‐IR detection. The chromatographic resolution and deposition quality were found to be unsatisfactory for SFC/FT‐IR; however, high temperature GC/FT‐IR produced excellent results. The chromatograms and spectra obtained allowed for the identification of poly‐dimethyl silicones and mono‐, di‐, and tri‐diphenylsubstituted poly‐dimethyl silicones. An automated method of baseline correction was developed that allowed functional group chromatograms due to molecules containing Si‐phenyl bonds to be constructed without significant interference from Si‐methyl bonds despite the fact that the Si‐C stretching mode of Si‐phenyl bands overlapped significantly with the strong ba

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractIn pre vious papers, 2,6‐di‐O‐methyl‐3‐O‐pentyl‐β‐cyclodextrin (CD) was demonstrated to be successful in separating volatile compounds, while avoiding the drawbacks of 2,3,6‐tri‐O‐methyl‐O‐methyl‐β‐CD in terms of column stability and operating temperature.Since a CD chiral selector of universal use has not yet been found, and at least two (or more) columns coated with different CD derivatives are therefore necessary for routine work, the performance of 2,6‐di‐O‐methyl‐3‐O‐pentyl‐γ‐CD, 2,6‐di‐O‐methyl‐3‐O‐(4‐oxopentyl)‐γ‐CD, 2,6‐di‐O‐pentyl‐3‐O‐(4‐oxo‐pentyl)‐β‐CD, and 2,6‐di‐O‐pentyl‐3‐O‐(‐4‐oxo‐pentyl)‐γ‐CD diluted in polysiloxanes for the separation of volatile compounds in aromas and essential oils will be illustrated; each column coated with each of the newly sy

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAn ethereal extract of wheat (Triticum aestivum) straw with a positive biological assay for allelopathic activity, has been analyzed by HRGC. By means of HRGC‐MS the extract composition was assessed as a complex mixture of organic acids and sterolic compounds. The sterolic fraction was subsequently separated and further studied by HRGC‐MS and HPLC‐MS. Among the thirty seven components identified, some described for the first time in wheat straw, two new ketostero's were characterized by means of their MS spectra. The potential of the particle‐beam (PB) interface in HPLC‐MS studies of unknown mixtures is exemplified and compared with that o

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe nematic compoundN‐4‐(2′‐(4″‐dodecyloxybenzoyloxy)‐4′‐do‐decyloxy)azobenzenyl‐4‐dodecyloxysalicylideneimine, known as LH, and its cupric complex, bis[N‐4‐(2′‐(4″‐dodecyloxybenzoyloxy)‐4′‐dodecyloxy)azobenzenyl‐4‐dodecyloxysalicylidene]iminato of copper (II), known as CuL2have been used as stationary phases for gas chromatography. The thermal properties of LH and CuL2have been determined with conventional metal columns, usingn‐alkanes as solute probes. Plots of InV0gagainst 1/Tclearly show the temperature transitions of LH and CuL2. The analytical capabilities of the two stationary phases were established by use of 25 m glass capillary columns. Satisfactory separations were obtained for positional hydrocarbon and halocarbon isomers, aromatic and polyaromatic comp

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractCapillary GC/sensory analysis was used to judge if dynamic headspace on sliced pulp and on intact fruit, and solvent extraction could collect the “character impact” and the “contributory” aroma compounds in peaches. Capillary GC/sensory data showed that the headspace techniques selectively recovered the “contributory” volatile compounds, which are strictly related to the characteristic odor of the various peach cultivars, whereas solvent extraction better quantified the “character impact” compo

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractQuantitative chromatographic analysis is liable to errors due to peak asymmetry because the uncertainty in the detected position of the end of the peak tail decreases the reliability of the computed peak area. This dependence may be a severe drawback whenever peaks of different areas must be compared, as in the case of calibration curves. A new approach to overcome the uncertainties of area calculation due to peak asymmetry is reported in this paper. The approach consists of calculating only the area included between the start and the maximum of the chromatographic peak. Simulated and experimental chromatographic data were used in this study. Both the peak start‐to‐peak maximum area (SMA) and the start‐to‐end or total area (TA) were calculated and the quantitative results were compared. Within the scope of this work it is concluded that the SMA yields calibration curves that are more linear and have intercepts closer to zero than the calibration curves obtained using

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180511

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY