摘要:

AbstractA specific and sensitive method for the determination of ethylenediamine in human plasma is described. The aqueous sample is treated withm‐toluoyl chloride, yielding theN,N′‐bis(m‐toluoyl) derivative of the diamine, which is extracted into dichloromethane and quantitated after “on column” methylation by capillary gas liquid chromatography with alkali flame ionization detection. The corresponding derivative of putrescine serves as internal standard. The assay is reproducible and calibration curves are linear over the concentration range 0.05 to 10 μg · ml−1. The lower detection limit is about 10 ng · ml−1. The structures of the compounds of interest eluting from the capillary column are examined by gas liquid chromatography/mass spectrometry. The assay has been applied to the analysis of ethylenediamine in plasma following the administration of aminophylline and ethylenediamine in a cross‐over study to patients with bronchopulmonary diseases. The method also proves suitable for measuring other primary and secondary amines and diamines in aqueous solutions by gas l

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091002

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

年代:1986

数据来源: WILEY

摘要:

AbstractA capillary chromatographic procedure using a fused silica column is described which can be used to quantitatively determine amino acids in plasma following the pre‐chromatographic “clean‐up” described in a recent paper [1]. In substituting this procedure for that involving a packed column, advantage has been taken of the greater resolving power to separate amino acids from background component peaks. In order to extend this advantage and provide a sound basis for quantitative analysis, the technique of cold on‐column injection was employed. As a result, good precision of standard analysis was obtained with relative standard deviation (RSD) values for all amino acids of less than 4%. Application of the entire procedure to plasma samples yields RSD values of better than 10% for all amino acids with recoveries ranging from 72% to 104%. Simultaneous determination of plasma amino acid levels by gas chromatography (GC) using capillary columns and by classical ion exchange (CIE) showed reasonable agreement. Statistical evaluation showed no significant difference between twelve amino acids. Values for the remaining two, namely, phenylalanine and histidine are significantly different (p<0.005). Comparison of the values obtained from GC capillary and packed columns reveals no significant difference between fourteen amino acids. Significant differences exist between results for phenylalanine and tyrosine (p<0.001). It is concluded that there is good agreement between data obtained by GC capillary and CIE techniques and that differences between results for phenylalanine and histidine are metho

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091003

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe bronchosecretolytic drug ambroxol can be reliably quantified in human plasma by high performance liquid chromatography. Plasma is buffered alkaline, extracted with ether, and the organic solvent back‐extracted with diluted acid. An automatically sampled aliquot is separated by reversed phase HPLC; the analyte is well separated from two metabolites that interfered strongly in earlier methods. UV detection at 230 nm enables a lower limit of quantitation of 5 ng/ml. Internal standardization with propranolol allows accurate and precise quantification. Evaluation of the optimized combination of mobile and stationary phase is described, and application of the method to experimental and clinical pharmacokinetic studies is illustrate

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091004

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

年代:1986

数据来源: WILEY

摘要:

AbstractFor chromatography with supercritical fluids (SFC), the dependence of the capacity ratios k′ and of the mean resolution Rmon temperature and pressure is presented as a three‐dimensional diagram. A sufficient number of test chromatograms were run for the diagram to lead to an isocratic network in form of a curved surface. The isocratic network possesses a characteristic shape and contains all information about the temperature and pressure dependence of k′ and Rmfor a given volume flow rate and chromatographic system. The specific system studied comprised pentane as the mobile phase, unmodified silica as the stationary phase, and a set of four polycyclic hydrocarbons as the test mixture. The isocratic net of this system allows interpolation of k′ and Rmfor any temperature and pressure. Together with similar experimental data from other systems, this allows qualitative forecasts about the isocratic nets of other

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091005

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn indirect UV photometric detection technique is described in which a low concentration of a UV‐absorbing compound (UVAC) is added to the mobile phase in reversed phase liquid chromatography, thereby making it possible for non UV‐absorbing compounds such as the lower alcohols to be detected by the UV detector. This happens because the injected analyte may extract a portion of the UV absorbing compound from the mobile and/or stationary phase and the complex is co‐eluted as a positive peak at the retention time of the analyte. Alternatively, the injected analyte may appear as a negative peak if the UV‐absorbing compound is transferred to the mobile and stationary phases. In any case, the injected compound appears either as a positive or negative peak depending on the relative polarities and concentrations of all the compounds in the system. In addition, the resulting excess or deficiency of detection agent in the stationary phase is eluted separately as a positive or negative peak, indicating that the system has returned to equilibrium. In the work described herein, the chromatographic conditions and variables of the indirect photometric technique were studied to develop a quantitative HPLC method for UV‐transparent compounds. It was found that under optimal conditions it is possible to determine some analytes quantitatively at concentrations as low

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091006

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn analytical method for the determination of non‐methane hydrocarbons (NMHC) in air was developed using simultaneously pressure and temperature programmed gas chromatography (GC) on a capillary column. The separation of C2‐C10 hydrocarbons was performed in a single GC‐run using a fused silica capillary column (FSCC) with a chemically bonded non‐polar stationary phase (CP‐Sil‐5‐CB). A combination of on‐column cryofocusing and GC reinjection provided baseline separation of C2 hydrocarbons at subambient initial temperature (−40°C). The cryofocusing was performed on the column head immersed in liquid nitrogen. Quantitative retention of all C2‐C10 hydrocarbons was achieved only when a temperature gradient is created along the cooled column section. The focused components are eluted from the column head without supplementary heating by removing the coolant. To eliminate matrix effects, the enrichment procedure was designed to remove CO2and H2O. The detection limit was found to be

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091007

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

年代:1986

数据来源: WILEY

摘要:

AbstractDeviations from the additivity of energy contributions to substance sorption energies, determined on the basis of thermodynamic studies of GC behavior of homologous series of organic compounds fall into two categories: one forn‐alkanes, the other for homologous series containing a functional group. A previously derived equation is proposed for homologous series, describing the deviation from the linear dependence of retention parameters with a propagating homologn‐alkyl chain. The equation permits calculation of retention parameters of homologs starting from the first member in gas‐liquid, gas‐solid, and liquid‐liquid systems. The results prove its universal appl

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091008

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

年代:1986

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091009

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

年代:1986

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091010

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

年代:1986

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240091011

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

年代:1986

数据来源: WILEY