ISSN:0935-6304    

DOI:10.1002/jhrc.1240150102

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe separation of the toxicologically important aldehyde acrolein from other carbonyl compounds by high performance liquid chromatography after derivatization to 2,4‐dinitrophenylhydrazones is critically discussed on the basis of a selection of published methods. A method is proposed whereby the compounds acrolein, acetone, and propanal may be reproducibly separated to baseline by a reversed phase HPLC procedure employing a ternary mixture of methanol, water, and acetonitrile as mobile phas

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150103

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

年代:1992

数据来源: WILEY

摘要:

AbstractA multichannel autosampler which can automatically analyze up to 20 samples in sequence has been developed for on‐line Curie‐point pyrolysis – capillary GC. The results obtained from the system show that the analysis of thermally labile samples could be performed without either thermal degradation or reaction during the waiting time before the final pyrolysis. The reproducibilities of the relative peak areas and retention times of the characteristic pyrolysates of a tricomponent copolymer were significantly better than those obtained by manual sample manipul

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150104

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe feasibility of using packed capillary HPLC for the analysis of small organic molecules has been demonstrated by three examples: the separation of glucose and sucrose telomers, the separation of the different components of a solvent extraction reagent, and the separation of mono‐, di‐, and trioleins, all of which have been achieved with packed capillary columns of 0.32 mm inner diameter and eluent flow rates of 3 microliters per minute. Application to the analysis of the solvent extraction reagents has shown that this technique can be used as a quantitative tool in just the same way as any conventional HPLC method.The feasibility of a direct packed capillary HPLC – mass spectrometry interface has been demonstrated for the glucose telomer separation; direct coupling is only possible because of the microliter flow rates employed by the tech

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150105

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

年代:1992

数据来源: WILEY

摘要:

AbstractA procedure for the identification and separation of unknown compounds by capillary gas chromatography is described. The procedure involves a live retention time database and optimization of the separation. After initial chromatography of the sample, a rough search lists all the possible compounds it might contain and the analyst then uses his experience to discard those compounds in the list which are unlikely to be present. The multi‐component separation is then optimized over the whole range of defined starting temperatures and programming rates, in order to produce the best possible separation of the sample components, and the chromatography repeated using the results obtained from the optimization procedure. Further search operations within a given search window will then report the compound names, and related information, for each peak.Since the identification operation is performed at least twice during the procedure, and the optimization of the separation assists the identification by separating possibly overlapped peaks, the confidence of the qualitative analysis is higher than may be obtained using standards alone. If the reproducibility of isothermal indices measured on columns could be guaranteed, this procedure could be used instead of performing chromatography on standards of the compounds contained in the database, regardless of changes in column dimensions, phase ratio, and operating conditions in temperature programmed analysi

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150106

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

年代:1992

数据来源: WILEY

摘要:

AbstractPost‐column derivatization of oligosaccharides after HPLC separation with a variety of systems has been achieved either by reaction with thymol in concentrated sulfuric acid or after hydrolysis of saccharides with hydrochloric acid and derivatization of the resulting monosaccharides withp‐aminobenzoic acid hydrazide. With both reactions the detection of reducing and non‐reducing sugars is possible even at trace levels. The latter reaction, despite the two reaction steps required, is much more convenient and practical, whereas with the first reaction it is also possible to determine alkylpolygluco

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150107

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

年代:1992

数据来源: WILEY

摘要:

AbstractCapillary zone electrophoresis in untreated fused silica capillaries has proved suitable for the determination of the ionization constants of weak electrolytes. Several fundamental equations relating the electrophoretic mobilities of ionized solutes to hydronium ion concentrations in the running electrolyte have been verified experimentally. The observed dependence of the electrophoretic mobilities of weak bases and ampholytes on the pH of the electrolyte showed good agreement with predicted behavior. The pKavalues calculated from electrophoretic mobility data obtained by capillary zone electrophoresis were reasonably close to those reported in the literature.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150108

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe determination of nanometer thick layers of poly(methyl methacrylate) coated on to the surface of poly(ethylene terephthalate) film has been investigated by high resolution pyrolysis gas chromatography without sample pretreatment or modification of the instrumentation used. A good linear relationship was observed between the quantity of the characteristic pyrolysate and the thickness of the poly(methyl methacrylate) layer; the detection limit was sufficient to enable the quantitation of poly(methyl methacrylate)‐to‐poly(ethylene terephthalate) film thickness ratios of 1:20000 in composite materi

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150109

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

年代:1992

数据来源: WILEY

摘要:

AbstractEnsemble or signal averaging has been used to increase detection limits in gas chromatography. The sample is injected several times into a gas chromatograph and the chromatograms generated are summed. The resulting chromatogram is treated as a separate chromatogram with the benefit of an improved signal‐to‐noise ratio. Use of the technique enables reliable quantitation, the time invested being used to convert an unacceptable signal‐to‐noise ratio into useful data. A discussion and some applications of the technique are de

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150110

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

年代:1992

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150111

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

年代:1992

数据来源: WILEY