摘要:

AbstractThe width of the molecular weight distribution (MWD) of polymer stationary phases influences their polarity and other gas chromatographic characteristics. The MWD of the most frequently used polyglycol‐type stationary phases such as Carbowax, Ucon, Emulphor and Pluronic has been determined and compared. The MWD determined by gel chromatography allows for the characterization of the actual batch of a stationary phase, provides a check on its consistency and helps to screen out the apparently less promising phase

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040102

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

年代:1981

数据来源: WILEY

摘要:

AbstractRetention indices were determined for a homologous series of n‐dialkyl sulphides on three stationary phases (SE‐30, OV‐17 and XE‐60) under isothermal and linear temperature programming conditions. Under these two different GC conditions, equations were derived for each of the three stationary phases which showed the dependence of retention index on the number of carbon atoms and the boiling points for a homologous series of n‐dialkyl sulphides. The equation for the correlation isothermal retention index was shown to be applicable to the identification of n‐dialkyl sulphides using linear temperature programming. It was found that the GC behaviour of n‐dialkyl sulphides makes these compounds suitable for use as a standard series instead of n‐alkanes for the calculation of retention indices in GC analysis in which detectors insensitive to n‐alkanes are employed. The use of the homologous series of n‐dialkyl sulphides for the calculation of sulphide retention indices can be great practical importance in the microanalysis of natural compounds. We have used this method successfully in the analysis of pesticides

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040103

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

年代:1981

数据来源: WILEY

摘要:

AbstractA single‐step coating method for the preparation of glass capillary SCOT columns is described. It is reproducible and less time‐consuming than the well‐known two‐step coating procedures. Other methods attempted are discussed briefly. Both the flame ionization and electron capture detectors could be used in conjunction with temperature programming. The separations achieved with an “activity mixture”, phenols and phenolic acids, illustrate the resolution obtained. The columns are suitable for quantitative determinations and a comparison is made with a conventional pa

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040104

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

年代:1981

数据来源: WILEY

摘要:

AbstractIn this paper the equation for thin‐layer adsorption chromatography with multicomponent mobile phases, proposed by Ościk in 1965 is extended to energetically heterogeneous solid surfaces. Other forms of this equation, more convenient in practical applications, are presented. Model calculations are made for TLC with binary mobile phases according to the modified form of Ościk's equation. Finally, this equation is compared with that of Sny

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040105

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

年代:1981

数据来源: WILEY

摘要:

AbstractDifferent chromatographic methods for determination of methyl hydroxybenzoate and propyl hydroxybenzoate in pharmaceutical formulations are compared. Procedures for HPTLC, HPLC and GC/MS are given.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040106

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe effect of temperature on the efficiency of column systems in adsorptive liquid chromatography is reported. The influence of temperature changes on the values of the terms Cm2 and Ck in the HETP equation, which characterizessystems involving silica gel and benzene, ethylene chloride, butyl ether or cyclo‐ hexanone + heptane, is discussed for 9 substances. The results of the study have led to the following conclusions:1Temperature increase will always improve the efficiency of typical chromatographic systems.2As expected, an essential role is played by mass transfer resistance in the mobile phase occupying the pores of the packing material (parameter Cm2).3Mass transfer resistance resulting from sorption‐desorption kinetics (Ck) does not play as essential a role in the systems investigated as does Cm2, but its value is significantly higher than that reported in the literat

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040107

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

年代:1981

数据来源: WILEY

摘要:

AbstractThirty‐two priority pollutants can be analyzed in water with detection limits of 10 ppb by direct liquid chromatography. High sensitivity is obtained by use of an ultra‐violet detector at 202 nm and a reverse phase C18column with a water‐acetonitrile gradient that is compatible with two milliliter water sa

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040108

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

年代:1981

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040109

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

年代:1981

数据来源: WILEY

摘要:

AbstractCardenolides ofConvallaria majaliswere separated by reverse‐phase HPLC on Partisil PXS 10/25 ODS columns using 25% acetonitrile as mobile phase. Periplorhamnoside, convallatoxin and either convallatoxol or convalloside were resolved from glycoside mixtures. Convallatoxin and periplorhamnoside were identified in plant extracts, convalloside and convallatoxol were not resolved from non‐cardenolide material present in leaf extra

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040110

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

年代:1981

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240040111

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

年代:1981

数据来源: WILEY