摘要:

AbstractA method was developed to analyze and quantitate volatile fatty acids such as acetic, propionic, butyric, iso‐butyric, valeric, and iso‐valeric acid from samples of biological origin. A capillary column system including an automatic on‐column injection device as well as a precolumn of larger internal diameter than the analytical column was elaborated for this purpose.In order to obtain well resolved and correctly quantifiable chromatographic peaks it turned out to be essential to work under acidic/aqueous conditions. To achieve a better sample transfer into the chromatographic system an organic solvent had to be used together with the aqueous milieu, thus improving wetting properties of the liquid sample plug introduced into the column. Cold on‐column injection was applied in order to avoid discrimination of the various acids due to sample splitting and the automatic technique was chosen in view of the large number of samples from biological extractions which had to be a

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110132

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe applicability of dynamic headspace analyses for viscous liquids and solid samples is demonstrated. Some comments on the usefulness of this technique for quantifying volatiles in polymeric matrices are made.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110133

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

年代:1988

数据来源: WILEY

摘要:

AbstractGas‐chromatographic analysis of complex mixtures is simplified enormously by the use of the simultaneous dual capillary technique. The advantages over a single‐column system are that the components are more reliably identified and quantified. After integration has taken place, the data from both capillaries are cor‐related with the aid of a computer program whose principles are desc

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110134

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

年代:1988

数据来源: WILEY

摘要:

AbstractIntroduction of solutions of up to several milliliters by on‐column injection of large volumes or by coupled HPLC‐GC may cause problems with GC detectors (FID, AFID, MS). For instance, dichloromethane forms large amounts of hydrochloric acid and carbon black in FIDs.A column effluent splitter was developed for keeping the major portion of the solvent vapors away from the detector; approximately 99% of the vapor is vented while the remaining 1% of vapor is used for detecting the widths of the solvent peaks. During analysis, the split ratio is reversed by a strong increase of the resistance to the gas flow through the split exit line.The system was used for the determination of di‐(2‐ethylhexyl)‐phthalate (DEHP) in triglyceride matrices of various foods. Direct determination by HPLC is not sufficiently sensitive, whereas direct analysis by GC is hindered by the triglycerides. Solutions of fats or oils were pre‐separated on a silica column using dichloro‐methanelcyclohexane 1:l with addition of 0.05 % acetonitrile as eluent. The HPLC fraction containing the DEHP was transferred to GC through a loop‐type interface using concurrent solvent evaporation. Detection limits were

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110135

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

年代:1988

数据来源: WILEY

摘要:

AbstractThree different injection modes were compared for the analysis of organophosphorus pesticides. Differing results were found for several compounds depending on their chemical structure and thermostability. The programmed temperature vaporizing injector used in this study seemed to be the most promising sampling device for pesticide residue analysis in biological samples.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110136

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110137

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

年代:1988

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240110101

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

年代:1988

数据来源: WILEY