摘要:

AbstractA procedure is described for the analysis of the estrogens equilin and estrone in human plasma following oral administration of conjugated estrogen preparations. After enzymatic hydrolysis of the sulfate conjugates, plasma proteins are precipitated with methanol and the estrogens extracted into ethyl acetate. Derivatization with the reagent flophemesylamine converts equilin and estrone into volatile pentafluorophenyldimethylsilyl ethers ideally suited to capillary gas chromatography‐negative ion chemical ionization mass spectrometry. Using a 15 meter dimethyl silicone bonded phase fused silica capillary column separation of the estrone and equilin derivatives is achieved within 9 minutes. Selected ion monitoring of the intense negative molecular ions enables levels of 1 ng.ml−1to be measured with coefficients of variation of 9.3 % and 14.2 % for estrone and equilin respectively. Plasma levels of the compounds are reported in two male volunteers up to 24 hours after dosing with 5 milligrams of Premarin™. (™ Ayerst Laboratories Inc., New York

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100102

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

年代:1987

数据来源: WILEY

摘要:

AbstractAnalysis of anions by HPLC has been optimized in the direction of reduced analysis times with standard reversed phase columns and UV detection. This was achieved by use of a new eluent containing 3‐nitrophthalic acid and small proportions of acetonitrile. Resin‐based and silica‐based anion exchangers of varying ion‐exchange capacities are prepared with cetyltrimethylammonium bromide by a rapid dynamic coating technique. Some new, strong eluents containing nitrophthalic acids are evaluated and compared with an eluent containing potassium hydrogen phthalate. Addition of acetonitrile was found to improve the retention behavior of mono‐ and divalent anions. An automatic system was developed for the analysis of chloride, nitrate, and sulfate in drinking water. It is shown that a water sample can be analyzed in less than two minutes on a column of 25

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100103

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

年代:1987

数据来源: WILEY

摘要:

AbstractTrace enrichment for the GC analysis of a series of chlorinated pesticides and polychlorinated biphenyls (PCBs) in aqueous samples has been achieved through a simple on‐line technique involving sorption on an LC micro‐precolumn followed by direct elution into a gas chromatograph with hexane. A 5‐m retention gap coupled to the capillary GC column served as the recipient of a relatively large sample volume (ca.100 μl) introduced into the GC. Partially concurrent solvent evaporation during sample introduction allowed a large sample capacity. Recoveries of more than 95% were observed for the majority of the compounds studied. Using 1.0 ml aqueous samples, detection limits of less than 1 ppt were found. The applicability of the developed method was demonstrated for a river water

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100104

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe content of residual monomers is one of the most important characteristics of polymer dispersions. As a result of the similar physicochemical parameters of ethyl acrylate and methyl methacrylate, it is very difficult to determine the residual monomers in acrylate dispersions obtained by emulsion polymerization of both monomers. Gas chromatography with capillary columns, however, permits separation of these monomers and their quantitative determination in acrylate dispersions.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100105

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

年代:1987

数据来源: WILEY

摘要:

AbstractMicrobore columns (1 mm i.d.) are compared to conventional 4.6 mm i.d. columns with respect to speed, efficiency and sensitivity. If column lengths, particule diameter, packing efficiency, mobile phase, and linear velocity are the same, most chromatographic properties such as speed (analysis time), efficiency, pressure drop, and sensitivity are the same. The major differences are the column volumes, the void volumes, and the volumetric flow rates for equal linear flow velocities. The low flow rates of microbore columns (30 to 200 μl/min), conserve solvent and make for easier interfacing to other instruments such as MS, NMR, or FTIR. Temperature programming of microbore HPLC columns produces faster analyses for large k′ values, increased sensitivity (due primarily to sharper peak shape), and increases the range of compounds which can be handled in an isocratic mo

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100106

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

年代:1987

数据来源: WILEY

摘要:

AbstractUsing UCON 50 HB‐5100, one of the most successful stationary phases in capillary gas chromatography during the past decade, as an example, we wish to redirect attention to the excellent properties of the polyethylene/polypropyleneglycol ether copolymer coatings. Based on experience gained in work with OH‐terminated polysiloxanes, a method is described for preparing inert and relatively temperature stable chemically bonded and crosslinked coatings in a single working step. Methyltrimethoxysilane was used as coupling agent, and trifluoroacetic acid was introduced as an acidic catalyst. The reaction mechanisms involved as well as the influence of additional crosslinking on the column behavior are discussed, particularly with respect of the inertness of the coati

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100107

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100108

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100109

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100110

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

年代:1987

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240100111

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

年代:1987

数据来源: WILEY