摘要:

AbstractAs a continuation of previous studies on the use of cyclodextrin derivatives (CD) for the separation of volatile compounds by capillary GC, the influence of diluting phases other than OV‐1701 or OV‐1701‐OH has been investigated.2,6‐Di‐O‐methyl‐3‐O‐pentyl‐β‐cyclodextrin (2,6‐DiMe‐3‐Pe‐β‐CD) was taken as the reference CD derivative, because of the large number of volatile racemates it is able to separate; OV‐1701 or OV‐1701‐OH was chosen as the reference diluting phase.The performance of a column coated with a 0.15 μm film of 10 % 2,6‐DiMe‐3‐Pe‐β‐CD in OV‐1701 was compared with that of analogous columns coated with films of the same thickness containing the same percentage of the CD derivative diluted with stationary phases of different polarity,i.e.PS‐086, PS‐347.5, and OV‐225. Resolution values and separation factors of thirty racemates were used to evaluate th

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160402

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

年代:1993

数据来源: WILEY

摘要:

AbstractImmobilized polysiloxane‐anchored permethyl‐β‐cyclodextrin (Chirasil‐Dex) with a cyclodextrin content of approximately 30 % by weight, previously employed as a versatile chiral stationary phase for the separation of enantiomers by GC, has been used for the separation of enantiomers by capillary supercritical fluid chromatography (SFC). A considerable number of racemates could be resolved,e.g.aromatic alcohols, amino alcohols (TFA derivatives), and underivatized acids. Many pharmaceutical compounds were among those analyzed, including several NSAIDs (e.g.ibuprofen and ketoprofen), a steroidal drug (nor‐gestrel), a barbiturate (hexobarbital), and others.Among the racemates resolved were many which cannot be analyzed by GC owing to low volatility or decomposition at elevated temperatures. For two racemates, analysis temperature and mobile phase density were systematically varied to give constant analysis times or capacity factorsk.Low temperatures (ca60 °C) yielded the best separation in term of separation factor, α, or resolution,Rs, even though higher densities had to be used. In comparison with GC, capillary SFC was able to furnish higher separation factors and similar resolution. The applicability of capillary SFC for the analysis of mixtures of cyclodextrin derivatives,e.g.those used in the synthesis of Chirasil‐Dex, was, furthermore

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160403

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

年代:1993

数据来源: WILEY

摘要:

AbstractExperiments with splitless injection of large volumes of aqueous samples by the overflow technique have shown that an organic co‐solvent is necessary to help the packing material (Tenax) retain the liquid. With 25–30% propanol or 15–20% 2‐butoxyethanol, some 800 μl can be injected into a 5 mm i.d. liner. The application of the method is restricted to components eluting above

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160404

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

年代:1993

数据来源: WILEY

摘要:

AbstractA method employing a wide pore polymeric reversed phase column has been developed for the separation of most of the chlorophylls and related compounds previously described as occurring in marine microalgae. The high selectivity toward molecular shape of this kind of stationary phase has enabled compounds of very similar structure, such as chlorophylls c1, c2and Mg‐divinylpheoporphyrin a5monomethyl ester, and chlorophyll a and the phytol‐substituted chlorophyll c‐like pigments, which commonly coelute on monomeric bonded phases, to be resolved in a single run. Some of these pigments, formerly thought to be a single compound, have, in fact, been demonstrated to be groups of two or more. The method has been successfully applied to both algal cultures and natural sea water samples. When visible light absorbance detection was used, the method proved suitable for separation of various carote

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160405

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

年代:1993

数据来源: WILEY

摘要:

AbstractSupercritical fluid extraction (SFE) coupled “off‐line” with HPLC analysis has been applied to pharmaceutical analysis: two different matrixes (rodent and dog feed) were spiked with compounds under investigation in pharmacological studies in order to study the supercritical extraction of such matrixes prior to further analysis and quantification of the compounds of interest.The fluid flow‐rate in the SFE system was governed by the geometric characteristics (internal diameter and length) of the linear fused silica capillaries. The changes in fluid flow‐rate, between experiments, for each new restrictor, required the introduction of the term Total Gaseous Fluid Volume (TGFV), which enabled a series of extraction results to be compared.The comparative behavior of nitrous oxide and carbon dioxide as supercritical extraction fluids was investigated. Results obtained using pure supercritical fluids with high solvating power (density 0.79 g ml−1) and fluids modified with a polar liquid solvent (methanol and acetonitrile) ar

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160406

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

年代:1993

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160407

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe quantitative CE analysis of fluorine and monofluorophosphate in toothpastes is described. Separation is performed using a Waters CIA‐Pak chemistry kit with Waters Electro Osmotic Flow Modifiers on a CE instrument from Spectra Physics (Spectra‐phoresis 500) at elevated temperatures up to 40 °C and at a low temperature of 10 °C. The quantitative results and the simplicity are compared for the CE method, the existing standard GC procedure described in the Official Journal of the European Communities, and the procedure employing a fluoride‐ion‐specific

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160408

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

年代:1993

数据来源: WILEY

摘要:

AbstractAn unmodified split/splitless inlet system using forward‐pressure controlled pneumatics was operated in splitless injection mode with several inlet liners under a range of septum purge flow rates. The relative recovery (discrimination) of hydrocarbons ranging fromn‐C8ton‐C20depended strongly upon the injected sample volume with open‐ended liners at high septum purge flow rates ofe.g.50 mL/min. Little or no discrimination was observed at septum purge flows of 2–3 mL/min. The same inlet was also operated in a back‐pressure regulated configuration that produced mass discrimination similar to that observed with the higher septum purge flows in the forward‐pressure configuration. An inlet liner with a restricted inlet and outlet gave mass‐discrimination levels independent of septum purge flow rate, but in the reverse sense of that observed with open‐ended liners. Preferential volatile‐component losses out of the inlet liner to the septum purge vent are principally responsible for the observed mass discrimination with openended liners, while mass‐dependent losses with doubly‐restricted liners seem due to

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160409

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

年代:1993

数据来源: WILEY

摘要:

AbstractPreparative resolution of the enantiomers of several chiral dihydrofuranones, known to be important flavor compounds, has been achieved by combining the use of bonded β‐cyclo‐dextrin as chiral stationary phase with closed‐loop recycling chromatography. The purity of the separated enantiomers has been determined by chirospecific capillary GC analysis, using heptakis(2,3‐di‐O‐methyl‐6‐TBDMS)‐β‐cyclodextrin as the ch

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160410

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe background of the new Unified Nomenclature for Chromatography just accepted by the International Union of Pure and Applied Chemistry (IUPAC) is explained and selected highlights of the new rules are elaborated.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240160411

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

年代:1993

数据来源: WILEY