ISSN:0935-6304    

DOI:10.1002/jhrc.1240120802

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

年代:1989

数据来源: WILEY

摘要:

AbstractMethodologies for quantitative analysis of amino acids in physiological fluids based on classical ion exchange, high performance liquid chromatography, and gas chromatography are analyzed. As judged by the relative number of reports on these techniques, it appears that classical ion exchange continues to be the main method of choice for amino acid determinations and only limited advantage has been taken of the benefits (e.g.lower capital outlay and running costs and shorter analysis times) offered by other techniques. More importantly, however, there appears to be insufficient quantitative evaluation of the methodologies used. As a result, the validity of many reports based on data from amino acid analysis of physiological samples may be questioned.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120803

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

年代:1989

数据来源: WILEY

摘要:

AbstractAutomated large volume (25‐200 μl) on‐column injections into a gas chromatograph with a capillary column were successfully performed by coupling a retention gap technique with an air actuated rotary valve. The linearity, injection precision, and carryover were evaluated. Slight boiling point discrimination was observed. This technique is compatible with commonly used chromatographic detectors (FID, ECD, MS) and conditions, while requiring very little instrument modification. The work is directed at the eventual reduction of manpower and turnaround time for sample collection and extraction, and Kuderna‐Danish concentration when dealing with methods similar to E

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120804

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe performance of the gas chromatography/alternating current plasma detector as a selective detector for organolead compounds is investigated. The helium make‐up flow rate and the spatial position from which the lead emission is viewed, have an effect on the detector response. The detection limit for tetrabutyl lead was established as 130 pg/s and the lead selectivity ratio was found to exceed 13,800. Some applications of organolead determination in complex matrices were also studied in order to demonstrate the selectivity and sensitivity of the alternating current plasma detecto

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120805

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

年代:1989

数据来源: WILEY

摘要:

AbstractA simple method has been developed for the direct coupling of supercritical fluid extractions (SFE) with a high resolution gas chromatograph (HRGC) equipped with an electron capture detector (ECD). SFE conditions have been investigated for polychlorinated biphenyls (PCBs) from sediments in terms of mobile phase, entrainer, pressure, temperature, and mass‐flow through the extractor. Dynamic leaching and static steady‐state extractions were compared. Extraction efficiencies of up to 100% in less than 15 minutes have been obtained. The extracted PCBs are quantitatively transferred into a fused silica open tubular column (OTC). Determination of PCBs was tested on certified sediment from National Water Research Institute and the results agreed well with certified val

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120806

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

年代:1989

数据来源: WILEY

摘要:

AbstractChiral γ‐lactones from the raw flavor extract of strawberries and some commercially available fruit‐containing food and beverages were stereoanalyzed directly by multidimensional gas chromatography (MDGC) employing heart‐cutting techniques from DB‐1701 as the preseparation column onto heptakis (3‐O‐acetyl‐2,6‐di‐O‐pentyl)‐β‐cyclodextrin as th

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120807

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

年代:1989

数据来源: WILEY

摘要:

AbstractA new mixed crosslinking agent composed of dicumyl peroxide and tetra(methylvinyl)cyclotetrasiloxane was used to prepare fused silica capillary columns within situcrosslinked stationary phases including PEG‐20M, SE‐54, and OV‐1. These columns proved to have good thermostability and inertness. As examples of potential applications a mixture of isomers of nitrotoluene and dinitrotoluene, and pyrolyzates of polystyrene were separated by using these co

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120808

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

年代:1989

数据来源: WILEY

摘要:

AbstractA sensitive and specific method for the determination of valproic acid in plasma has been developed. After the proteins in the plasma have been precipitated with a saturated solution of ammonium sulfate in 1NHCl, the valproic acid, together with the internal standard, is extracted from the plasma with dichloromethane.An aliquot of the organic solution is taken for derivatization of the valproic acid and the internal standard withO‐p‐nitrobenzyl‐N,N′‐diisopropylisourea.Separation is carried out by HPLC using two chromatographic systems: an adsorption system with a μ Porasil column, hexane‐chloroform (94:6) as mobile phase, and caproic acid as internal standard and a partition reverse phase system comprising a μ Bondapak TM/C18column, acetonitrile/methanol/0.0035Mphosphate buffer (60:10:30), and caprylic acid as internal standard. UV detection is at 254 nm.This method, developed in both systems, permits the determination of plasma levels of valproic acid in the reported range of 50‐100 μg/mL. With adequate sensitivity, specificity, precision, and accuracy.The plasma levels of valproic acid may be determined by this method without interference from the commonest antiepileptic drugs. Good correlation is obtained with the enzymatic immune analy

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120809

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

年代:1989

数据来源: WILEY

摘要:

AbstractSimultaneous recording of UV and mass spectra (electron impact or chemical Ionization) in conventional HPLC is described. The LC eluent is divided into two parts; one is directed into a diode array detector and the other is introduced into the mass spectrometer via a particle beam interface. The analysis of the steroid esters of a pharmaceutical formulation illustrates the possibilities of dual channel (DAD‐MS) HPLC detectio

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120810

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

年代:1989

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120811

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

年代:1989

数据来源: WILEY