摘要:

AbstractThe chromatographic performance of 50 μm internal diameter (i.d.) fused silica columns coated with up to 2 μm films of immobilized SE‐54 (methyl phenyl (5%) silicone) is evaluated under gas chromatographic conditions. The influence of pressure drop on the plate height is discussed. In comparison to thick film 250–530 μm i.d. columns, much higher efficiencies and faster analyses are obtained. Practical examples, performed on a standard GC instrument, illustrate the features of thick film 50 μm i.d.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180202

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

年代:1995

数据来源: WILEY

摘要:

AbstractHaloacetates in various environmental compartments can be determined by gas chromatography‐negative‐ion chemical‐ionization mass spectrometry after derivatization with 1‐pentafluorophenyl diazoethane. Detection limits in absolute amounts per injection are between 0.01 fg (chlorodifluoroacetate) and 80 fg (monofluoroacetate). Sampling of haloacetates in urban air was performed by means of cylindrical denuders coated with alkalized glycerol. The haloacetates detected are trifluoro‐, monochloro‐, dichloro‐, trichloro‐, monobromo‐, and dibromoacetate. The concentrations in ambient air fluctuate strongly,e.g.between 20 and 3000 pg/m3for TFA. Haloacetates are also found in river waters and tree foliage. A major problem is interference from contamination with trifluoro‐ a

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180203

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

年代:1995

数据来源: WILEY

摘要:

AbstractA novelp,p‐cyanobiphenyl stationary phase (p‐cyanobiphenyl,p‐allyloxy methylpolysiloxane) has been evaluated for the GC investigation of polychlorinated biphenyls (PCBs). Several PCB congeners which coelute on the phases typically used for PCB analysis (e.g.5% phenyl methylpolysiloxane) are separated on thep,p‐cyanobiphenyl phase, including the hexachlorobiphenyl congeners PCB 163, PCB 164, and PCB 138. In this work, ap,p‐cyanobiphenyl stationary phase was used to measure selected PCB congeners in two Standard Reference Materials (SRMs) available from the National Institute of Standards and Technology (NIST), and two Certified Reference Materials (CRMs) available from the Community Bureau of Reference (BCR). The materials analyzed were SRM 1588, Organics in Cod Liver Oil; SRM 1945, Organics in Whale Blubber; CRM 349, Chlorobiphenyls in Cod Liver Oil; and CRM 350, Chlorobiphenyls in Mackerel Oil. Concentrations are reported for several PCB congeners which coelute on the 5% phenyl methylpolysiloxane, including PCB 163 an

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180204

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe wide range of lipid classes found in plant tissues, including simple lipids, glycolipids, and phospholipids, have been resolved by gradient high performance liquid chromatography with evaporative light‐scattering detection. The lipids from potato tubers were used to optimize the separations. Adsorption chromatography with silica gel gave disappointing results for the plant glycolipids. Much better separations were obtained with chemically bonded stationary phases,e.g.those with propionitrile or polymeric vinyl alcohol as the functional moiety. With careful calibration, good reproducibility was possible. Only highly acidic lipids such as phosphatidylserine still present some problem

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180205

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

年代:1995

数据来源: WILEY

摘要:

AbstractVolatile secondary metabolites from Colombian ylang‐ylang flowers were obtained by combined steam distillation ‐ solvent extraction. The samples were analyzed by high resolution gas chromatography with flame ionization, nitrogen/phosphorus, or mass spectrometric detection. The chemical composition of the oils extracted from flowers at different stages of development differed both qualitatively and quantitatively. The generation of total volatile metabolites, light oxygenated compounds in particular, increased markedly during flower maturation. In this work the quality of the ylang‐ylang essential oils was studied as a function of flower mat

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180206

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

年代:1995

数据来源: WILEY

摘要:

AbstractSilver ion chromatography, utilizing two commercially available HPLC columns connected in series, was used to separate a variety of triacylglycerol positional isomers. The isomers had a fatty acid composition of ABA and AAB, where A and B were fatty acids containing zero to three double bonds. Isocratic solvent systems of 0.5% to 1.0% acetonitrile in hexane were used to separate the triacylglycerol isomers. This methodology can be used to rapidly determine the isomeric purity of synthesized or isolated triacylglycerols and to isolate specific positional isomers.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180207

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

年代:1995

数据来源: WILEY

摘要:

AbstractA GC method for the determination of oxygenated additives in reformulated gasolines (RFG) is described. The method uses on‐column injection and atomic emission selective detection of oxygenates using the 777 nm NIR emission line. Detection limits are approximately 10 ppm oxygen. Results compared well with other techniques, such as GC/FTI

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180208

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe CGC analysis of 25 organophosphorus and organonitrogen pesticides was optimized on two different stationary phases, namely a 5% diphenyl dimethyl silicone (SE‐54 type) and a 50% diphenyl dimethyl silicone (OV‐17 type) by selecting the best temperature program conditions, using computer simulat

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180209

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

年代:1995

数据来源: WILEY

摘要:

AbstractCapillary zone electrophoresis (CZE) was employed in polyimide composition analysis. Polymide was decomposed to its corresponding aromatic diamine and aromatic acid monomers by an alkali fusion reaction. Sample treatment is much simpler than published methods, and electropherograms show a good separation of decomposed products under the proper conditions.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180210

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

年代:1995

数据来源: WILEY

摘要:

AbstractA way of controlling the maximum allowable oven temperature during on‐column injection by the column pressure drop is suggested. An arrangement using a restriction at the column outlet for adjustment of the column inlet pressure while maintaining the same column flow has been studied. Compared to non‐restricted flow, substantially increased maximum oven temperatures were obtained during on‐column injection. Injections at elevated temperatures resulted in an increased speed of analysis and decreased solute adsorption on the surface of the contaminated retention gap. The method is generally applicable to analysis of high boiling mixtures. In particular, with GC‐AED, such an arrangement yields a higher sensitivity due to an increased solute interaction with the excitation

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180211

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

年代:1995

数据来源: WILEY