摘要:

AbstractIn order to evaluate vloatile compounds, especiallly sesquiter‐penoids, in environmental and geological samples a method was penoids, in environmental and geological samples a method was required to characterize these components when they occur at low concentrations. After fractionation of the total sample extracts by TLC the aliphatic fractions were analyzed by HRGC AND THE kovats indices of all resolved peaks were calculated and comkpared with indices of all resolved peaks were calculated and compared with those obtained for commercial standards. As final step, the fractions were analyzed by HRGC‐MS and structures confirmed by comparison of their mass spectra with those of certified sesuiterpene standards. Additionally sesquiterpenoids present in the dissolved phase in water samples were concentrated by solid phase extraction using XAD‐2 resin. In this initial study, recovery tests with the resin were carried out in order to evaluate its performance rather than validating the method

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200602

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

年代:1997

数据来源: WILEY

摘要:

AbstractA system for purge‐and ‐trap with thermal desorption was developed and optimized to moniotor aroma compounds at ambient temperatures. Canned tomato juice volatiles were used as a model system to develop and evaluate the method. Volatile components were first adsorbed on insert‐traps packed with Tenax‐TA polymer, then thermally desorbed directly inside a gas chromatograph injector. Volatile matgerials occuring in Very low amounts could be entrained and subsequently chrfomatographed, with sensitivity limited by the purity of the sweep gas. Quantitative measurement of tomato juice volatiles was linear with sample size upn to 100 gram samples. The amount of trapped volatiles was proportional to trapping time; howver, low‐and intermediate‐boilers broke through the trap after one hour while high‐boilers continued to be retained. Apurge gas flow rate of 20ml/min gave optimum results mediate‐biolers. Optimum recovery of volatile compounds was obtained with a desorption temperature of 200°c for 5 min. Coefficients of variation from triplicate runs were relatively small. The method showed promise for a simple, sensitive, and reproducibel flavor volatiles collection system for the accurate analysis of

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200603

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

年代:1997

数据来源: WILEY

摘要:

AbstractThe plant family Compositae is known to produce a set of unusual fattly acids in their seed oil.Saussurea, a genus of the Compositae is less studied in respect to the fatty acid compsition of their seed oil. OnlySaussurea candicanswas reported to contain crepenynic acid (33%) as seed oil component.In continuation of our exploration of the portential of wild oil seeds, fatty acids in seed oils of sevenSaussureaspecies (S. amara,S. salicifolia,S. lipschitzii,S. pseudoalpina,S. pricei,S. parviflora, andS. dorogostaiskii) growing in Mongolia a were investigated by means of capillary GLC on capiallary columns of different selectivity (Silar 5 CP and BPX 70).γ‐Linolenic acid was found at levels up to 11% of the consitituent fatty acids ofSaussureaspp. seed oils. This is the first time that γ‐Linolenic acid has been found in members of the plant family Compositae. Moreover, the number, position and configuration of the double bonds in γ‐linolenic acid and that of other fatty acids was additionally confirmed by silver ion thin layer chromatography and infrared spectroscopy. The occurence and distribution of γ‐linolenic acid, which has found considerable interest for pharmaceutical and dietary use, may be of chemotaxonomical significance in the plant family

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200604

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

年代:1997

数据来源: WILEY

摘要:

AbstractThe recently developed tandem technique, mass spectroscopy with atmospheric‐pressure chemical ionization (APCI‐MS) coupled with direct flow injection, was applied to the determination of Bitrex (denatonium benzoate) and diethyl phthalate in ethanol. The compounds were indentified from their total‐ion chromatograms(m/z50‐500) and, simultancously, quantified using selected‐ion chromatograms recorded atm/z223 for diethyl phthalate andm/z325 for Bitrex. Operating conditions were optimized for soft ionization (positive ion‐mode) with fragmentation limited to that necessary for analyte identification, which was by the external‐standard method. Calibration curves were rectilinear in the concentration rages 2‐30 μg ml−1(Bitrex) and 0.075‐1.2%v/v(diethyl phthalate); measurement precision (RSDs were 11.48% for Bitrex and 2.22% for diethyl phthalate), and detection limits (0.017 μg ml−1and 0.010%v/v, respectively) were adequate for simiultaneous quantitation and with high sensitivity. The lack of any sample pretreatment and the use of flow‐injection analysis meant that the procedure was moere straightforward and rapid than pr

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200605

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

年代:1997

数据来源: WILEY

摘要:

AbstractThe applicability of a liquid‐liquid extraction system which is coupled on‐line with a capillary gas chromatograph was studied for environmental and ecotoxicological analyses. The optimized and automated system was used for the determination of apolar and rather non‐volatile organic compounds in aqueous samples. Relevant aspects of sample introduction, phase separation and selection of extraction solvent are discussed. Three routine‐tipe applications are described,viz. an improved method for the determination of hexachlorocyclohexanes in ground water and the determination of the so‐called NCC‐ether and ACC‐ether in ecotoxicological studies. Depending on the application studied, the concentration levels varied from 0.1 to 6000 μg/I, using ECD and/or FID detection. Typical coefficients of variation obtained with the total extraction–GC procedure were 2–25%.The system was found to be rugged, it saves time compared with set‐ups involving off‐line liquid‐liquid extraction and considerably redu

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200606

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

年代:1997

数据来源: WILEY

摘要:

AbstractEquations have been obtained for the dependence of relative retention and retention indexes on average column pressure. The equations suggested conform well with experimental data. It was shown that limiting value of relative retention (at the pressure approaches zero) is an invariant retention value. The nature of the stationary liquid phase used and its film thickness have a substantial influence on the dependence of relative retention and capacity factor on the pressure.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200607

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

年代:1997

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200608

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

年代:1997

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200609

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

年代:1997

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200610

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

年代:1997

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240200611

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

年代:1997

数据来源: WILEY