ISSN:0935-6304    

DOI:10.1002/jhrc.1240150502

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

年代:1992

数据来源: WILEY

摘要:

AbstractA novel two‐dimensional electrophoretic system for the control of electroosmosis in capillary zone electrophoresis has been developed and evaluated for rapid separations of proteins. The system comprises uncoated and polyether‐coated fused silica capillaries coupled in series. An equation relating the average electroosmotic flow velocity in the coupled capillaries to the intrinsic electroosmotic velocities of the connected segments and their corresponding lengths has been derived and verified experimentally. This approach has the advantage of enabling the electroosmotic flow to be tuned independently of the applied voltage. As a consequence, rapid protein analysis at relatively low field strength was achieved without sacrificing the high separation efficiencies obtained with surface‐modified capill

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150503

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe affects of alkali metal cations on the retention behavior of halide ions has been investigated. In general, the retention times of the anions were found to decrease as the size of the metal ion increased, although an inversion was observed for the rubidium and cesium ions. A similar inversion has been reported for calculated anion polarizabilities.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150504

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

年代:1992

数据来源: WILEY

摘要:

AbstractAn original theoretical approach, the “performance concept” is introduced.This concept enables the linear carrier gas velocity and column length to be optimized in order to obtain the shortest possible analysis time for a required separation. The optimized gas velocity and column length are expressed as functions of theBandCcoefficients of theHETPequation, the extra‐column equipment constant, σ2EC, and the necessary plate number,Nne, determined by the analytical problem. A new equation is given for predicting analysis time as a function of the same parameters.The validity of the concept is illustrated with an example of such an optimization. The fundamental relationships have been proved experimentally and excellent agreement found between predicted and measured

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150505

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

年代:1992

数据来源: WILEY

摘要:

AbstractA gas chromatographic method with alkali flame ionization detection is described for the determination of residue levels (0.1 μg/I and below) of deethylatrazine and deisopropylatrazine in drinking and ground water. Confirmation of the identities of the compounds is achieved by trifluoroacetylation, reaction conditions for which are presented

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150506

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe use of diethylene glycol monoethyl ether as a flavor solvent is restricted. Since existing methods of quantitation are tedious or require sophisticated multi‐dimensional GC instrumentation, a simple method has been developed using low cost GC‐MS. Monitoring of ions 31 and 45 enables quantitation of DEGEE in essential oils at levels down to 1 μg/g with accuracy equal to or better than

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150507

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

年代:1992

数据来源: WILEY

摘要:

AbstractA technique has been developed for performing headspace GC‐MS analysis of volatile components of food, in which the carrier gas flow is reversed during sampling in order to overcome problems caused by the diffusion of substances not retained by the cold trap. Chromatographic profiles of volatile compounds from cheeses, obtained at room temperature, provide confirmation of the validity of the reversed flow technique, and the versatility of the system is evidenced by its successful application to both solid and liquid matrixes: the absence of any discrimination against the various components reveals its efficacy for compounds with a wide range of volatility. Addition of internal standards to the sample enables the use of the technique for quantitative analysi

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150508

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe evaporative light scattering detector (ELSD) has been used in pharmaceutical analysis by liquid and supercritical fluid chromatography. An ELSD equipped with interchangeable interfaces enables the use of various eluents (UV‐ or non‐UV‐absorbing) in isocratic or gradient mode. Analyses were performed on several non‐UV‐absorbing excipients and active substances. The narrow spread of the response factors of the various compounds investigated has indicated that the detector is suitable for direct raw quantitation of unknown samples in stabilit

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150509

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

年代:1992

数据来源: WILEY

摘要:

AbstractForty five organochlorine pesticides (currently listed in EPA Method 8081A) have been chromatographed on DB‐5/DB‐1701 and SPB‐5/SPB‐1701 column pairs which were in each case connected to an inlet splitter and separate electron capture detectors. Thirteen additional compounds were evaluated for their suitability as internal standards or surrogate compounds for incorporation into Method 8081A. Method reproducibility and linearity are discussed, and results are presented for extracts of six real samples spiked with fifteen organochlorine pesticides and analyzed using the dual‐column, dual‐detector

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150510

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

年代:1992

数据来源: WILEY

摘要:

AbstractStatic headspace GC, a simple, clean technique which is easily automated, appears to be a good approach to the determination of solvent residues in pharmaceutical preparations. The feasibility of this approach has been studied with an automated system.Data is presented for the solvents designated as impurities in pharmaceutical preparations by the United States Pharmacopeia. It was found that the static headspace technique meets the United States Pharmacopeia criteria for sensitivity. The absolute area count precision was0.999. It was concluded that the technique is viable for this application.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240150511

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

年代:1992

数据来源: WILEY