ISSN:0935-6304    

DOI:10.1002/jhrc.1240120902

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe main principles of solid‐phase extraction techniques are reviewed in this paper. Various solid sorbents can be used as a suitable trap for direct accumulation of organic compounds from aqueous solutions. The trapped analytes can be desorbed by elution with suitably chosen liquid phases. These preconcentration procedures can be considered as low performance liquid chromatography and the efficiency of the procedure can thus be related to the retention characteristics of the preconcentration column. The main sorbents used for trace enrichment purposes are also reviewed. Besides, the concise methodology, sample storage, and automation are discussed. The advantages of solid phase extraction as compared to liquid‐liquid extraction are given as well as some drawbacks of this met

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120903

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

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper reports two subjects. It describes LC‐GC transfer by partially concurrent eluent evaporation at a greatly accelerated rate, as required for optimal compatibility with 2–3 mm i.d. LC columns and LC flow rates up to some 500 μl/min. Evaporation rates around 200 μl/min were obtained using a 0.53 mm. i.d. uncoated pre‐column and an early vapor exit. A stationary‐phasecoated “retaining” pre‐column was used for preventing escape of volatile solutes through the vapor exit.The technique was used for the detection of food irradiation by analyzing selected radiolysis products of triglycerides, namely alkanes/alkanes and aldehydes. Extracted fat of chicken, hazel‐nuts, and soup mixes was injected in LO and the relevant fractions were transferred on‐line to GC. For chicken and nuts, detection of irradiation was possible down to doses below 0.5 kGy. Detection limits were higher for soup mixes due t

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120904

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

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral agricultural compounds which are used as herbicide precursors have been analyzed by SFC and are detected on‐line via a flow cell FT‐IR interface. A mixture of ureas is separated on a microbore packed column; while a mixture of benzamides and anilides and a mixture of sulfonamides are separated on capillary columns. The use of 100% CO2as the mobile phase enables an infrared spectrum of each eluting analyte to be obtained on‐line with good signal to noise ratio. The urea mixture is also separated with a conventional cyanopropyl bonded phase analytical scale packed column using a methanol‐modified CO2mobile phase and UV detection. The separations achieved with and without modifier are c

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120905

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe determination of small, water soluble amines such as aziridine and 2‐chloroethylamine, in drug substances at trace levels is described. After removal of the bulk of the drug substance by extraction or precipitation, derivatization with acid chlorides is performed. In a two‐phase (water‐organic solvent) system, this derivatization reaction is accomplished almost simultaneously with the extraction of the product to the organic layer. The organic layer is analyzed by gas chromatography using on‐column injection and selective detection. Detection limits are approx. 0.2 mg/kg for aziridine and approx. 0.5 mg/kg for 2‐chloroe

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120906

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

年代:1989

数据来源: WILEY

摘要:

AbstractProfile analysis using capillary gas chromatography is applied in clinical chemistry to detect metabolic abnormalities. Examples are the increase of the urinary excretion of aromatic acids carrying a 4‐hydroxyl group and the decrease of hippuric acid in liver cirrhosis, and the elevated concentrations and excretions of dicarboxylic, oxocarboxylic, and hydroxycarboxylic acids in diabetes mellitus. Gas chromatographic quantitations, in some instances using mass selective detection, are performed on clinically relevant constituents. An example is the investigation of plasma and urinary hippuric acid and 3‐carboxy‐4‐methyl‐5‐pro‐pyl‐2‐furanpropionic acid in different stages

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120907

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

年代:1989

数据来源: WILEY

摘要:

AbstractSamples containing nitroaromatics have been taken from brooks and ponds in former ammunition production areas in Hessia (FRG) and Lower Saxony (FRG). The compounds were extracted by solid/liquid partition using Amberlite XAD 2/4/8 resins and elution with dichloromethane. The samples were analyzed by reversed phase high performance liquid chromatography and detected at their optimum wavelength with a photodiode‐array detector. The resulting UV‐spectra and the retention times were compared with those of reference materials to identify the unknown compounds. The recoveries ranged from 85–105%. The detection limit for the method was at about 50 ng/I depending on the compound while the detection limit for the detector ranged from 0.9–1.4 ng. Mononitrotoluenes, dinitrotoluenes, and 2,4,6‐trinitrotoluene, as well as nitrotoluidines, have been identified in concentrations ranging from 0.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120908

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe method of invariant relative retention value determination using commerciallly produced fused silica open‐tubular columns with different contents of stationary liquid phase has been tested. Invariant retention values are determined only by interaction of analyzed compound with stationary liquid phase and are independent of the adsorptive interactions in the studied syste

ISSN:0935-6304    

DOI:10.1002/jhrc.1240120909

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.1240120911

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.1240120912

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

年代:1989

数据来源: WILEY