ISSN:0935-6304    

DOI:10.1002/jhrc.1240190702

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

年代:1996

数据来源: WILEY

摘要:

AbstractPure enantiomers of chiral (atropisomeric) polychlorinated biphenyls (PCBs) obtained by high‐performance liquid chromatography were used to establish the gas chromatographic elution sequences of the (+)‐ and (−)‐enantiomers of six PCB atropisomers on Chirasil‐Dex. The elution order was found to be (−/+) for PCBs 84, 132, 136, and 176 and (+/−) for PCBs 135 and 174. The retention characteristics of all 19 tri‐ and tetra‐orthoatropisomeric PCBs were also investigated. Nine of the atropisomers could be separated using this chiral selector. PCBs 95, 132, and 149 were completely resovled and PCBs 84, 91, 135, 136, 174, and 176 were partially separated (R= 0.7–0.9). All of the separated congeners are 2,3,6‐substituted in at least one ring, and conversely – none of the congeners that lacks 2,3,6‐substitution could be separated. Thus, chiral recognition and enantiomer separation seems to be strongly gover

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190703

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

年代:1996

数据来源: WILEY

摘要:

AbstractQuantitative correlations between physicochemical parameters and structure of various solutes and their gas chromatographic behavior were investigated in order to predict the retention values. The identification of unknown samples in gas chromatographic routine analysis of environmental samples is enhanced by the use of these correlations in conjuction with other chromatographic methods and with mass spectrometry. The boiling points of many compounds are easily found in literature and therefore their correlation with retention values obtained in isothermal or programmed temperature analysis permit restriction of the choice of names of unknown compound to within a narrow range. The correlation between the boiling points and the retention times of chloro‐ and bromo‐benzenes and of some chloro‐ and nitro‐ substituted phenols was investigated on non‐polar capillary columns and permitted the tentative identification of many compounds belonging to these homologo

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190704

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

年代:1996

数据来源: WILEY

摘要:

AbstractTwelve compounds, commonly used as industrial solvents and belonging to the chemical class of glycol ethers and glycol ether acetates, were investigated. Several analytical conditions, applied to single or connected capillary columns of different length and polarity coating and connected to FID, O‐FID and MS detection systems, were assayed. Tests on heptafluorobutyryl derivatives were also attempted to improve the analytical sensitivity. The aims were to establish gas chromatographic methods suitable for analysis of reference standard compounds and to verify their applicability to biological matrix analysis for pharmacokinetic and toxicological studies, since these chemicals have been shown to be hazardous in laboratory animals and are presumed to be dangerous in ma

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190705

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

年代:1996

数据来源: WILEY

摘要:

AbstractChiral 2,2′,3,5′,6‐pentachlorobiphenyl (PCB 95), 2,2′,3,3′,4,6′‐hexachlorobiphnyl (PCB 132) and 2,2′,3,4′,5′,6‐hexachlorobiphenyl (PCB 149) were quantified in Atlantic Ocean shark liver samples (C. coelolepis) by gas chromatography‐mass spectrometry (GC‐MS) and their enantiomeric ratios were studied by multidimensional gas chromatography (MDGC) with an achiral‐chiral column combination and detected by ECD and MS/SIM. The concentration range of the chiral PCBs was from 2 to 6 ng/g (fresh weight), which represents 2–6 % of the total PCB mean concentration. The investigations revealed a small enantiomeric bias of PCB 132 in most of the samples studied (ER = 0.75–0.89, ee = 6–14%), while PCB 95 and PCB 149 were present

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190706

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

年代:1996

数据来源: WILEY

摘要:

AbstractApplication of solid phase deposition/supercitical fluid (SPD/SF) elution to real, brackish water samples, obtained from the Chesapeake Bay, has been investigated. The fortified (2ppb) brackish water samples contained suspended sediment, dissolved organic matter and salt. The sediment made post‐deposition drying of the SPE disk difficult and the residual water interfered with analyte recovery. Attempts to dry the disk included increasing the vacuum drying time, use of a higher percent of modifier, and desiccation. The best results were obtained by first drying the disk for 10 min under a stream of nitrogen, followed by overnight desiccation, and finally, SF elution. The SF method required a 3 step, 42 min extraction which reduced organic solvent use by 60% compared to traditional elution. All but five analytes met EPA criteria when fresh desiccant was used to dry the disk; four of the unacceptable recoveries were presumably due to plasticizer contaminatio

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190707

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

年代:1996

数据来源: WILEY

摘要:

AbstractCryogenic trapping of solutes leads to narrowing of the chromatographic band. By placing the trap at the end of a capillary column, it is possible to study the effectiveness of the trap in terms of producing a sharpened elution profile. The trap may be heated by supplementary heating, but here convective heating from the GC oven is employed simply by turning off the cryogenic coolant. It is estimated that it takes about 50 s for the trap to heat up sufficiently to allow trapped solute to be remobilized, although this depends upon the oven temperature and thermal mass of the trap. It can also be shown that the more volatile solutes mobilize faster from the trap in this particular mode of operation. The recovery of trapped components shows that there is essentially quantitative trapping, and the solutes are trapped just at the leading edge of the trap.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190708

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

年代:1996

数据来源: WILEY

摘要:

AbstractA capillary electrophoretic method for simultaneous determination of six bioactive ingredients (berberine, palmatine, baicalin, sennoside B, emodin, and sennoside A) in the Chinse herbal formulaSan‐huang‐hsieh‐hsin‐tangwas established. A carrier composed of aqueous buffer solution (50 mM sodium cholate, 15 mM sodium dihydrogen phosphate, and 4.25 mM sodium borate)‐acetonitrile (3:2) was found to be the most suitable electrolyte for this separation. Contents of these constituents in a non‐pretreated methanol‐water extract ofSan‐huang‐hsieh‐hsin‐tangsample could be easily determined within 20 min. The effects of borate, cholate, and organic modifier (acetonitrile) concentration of the carrier on the migration behavior of the solu

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190709

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

年代:1996

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190710

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

年代:1996

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240190711

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

年代:1996

数据来源: WILEY