Development of molecular imprinted polymers is a technology that utilizes functionalized polymers formed in the presence of a 'print' molecule (the analyte of interest).The polymer is then ground into a fine powder and the analyte extracted from the polymer leaving a molecular imprint of the analyte in the polymer.Molecular recognition is attributed to the formation of functional groups in a particular arrange- ment within the polymer matrix which conforms to that of the print molecule used in polymer synthesis.Shape-selective cavities also are thought to contribute to analyte binding.Automatic nitrogen/protein determination using the dynamic flash combustion method as an alternative to the Kjeldahl method

Fast and efficient separations of chiral stereolabile compounds were obtained at very low temperature on a pi-acid chiral stationary phase (R,R-DACH-DNB) using carbon dioxide-based mobile phases containing alcoholic polar modifiers.Furthermore, efficient separations of the newly discovered spherical carbon cluster buckminsterfullerene (C-60) and the related higher fullerenes (C-70, etc.) have been performed on the same stationary phase using eluents based on either n-hexane or carbon dioxide.

Urine samples from C3H congenic house mice (Mus domesticus) differing only at thet complex were examined by capillary gas chromatography to assess variations in the volatile components that may cause olfactory discrimination between animals bearingt lethal and+(wild-type) haplotypes. Urine was collected from 192 males and females varying in age from 1 to 9 months. C3H congenic mice that have the same genetic background at all loci but differed in theirt complex genotypes: +/ +, +/tw1,T/t w1, T/+ were used. No urinary volatiles were unique to thet complex. However, significant differences amongt complex genotypes and among ages occurred for concentrations of 12 male volatiles and four female volatiles. Usually young males (1-2 months of age) had significantly higher concentrations of cyclic enol ethers and ketones than older males (4-9 months of age). Moreover, some urinary volatiles (cyclic enol ethers, one ketone, dehydrobrevicomin, and thiazoline) were excreted in the urine of T/+and/orT/t males in significantly higher concentration than in the urine of +/+ males. Age andt complex genotype influences on the urinary volatiles in females were observed for four ketones. Gas chromatography of urinary components has the potential to be used in field studies of thet complex because the two t complex genotypes found in wild populations, +/+ and +/t, had significant differences in concentration for two males volatiles and three female volatiles.

Packed capillary columns in liquid chromatography provide several advantages over conventional HPLC: namely, higher efficiencies, improved detection sensitivity, and lower solvent consumption. Certain demands are placed on the instrumental design for this type of microchromatography. A miniaturized and optimized fully automatic system for gradient elution packed capillary liquid chromatography is described. Its performance at flow rates of a few μL/min, typical of this type of microcolumn, is demonstrated in terms of retention time reproducibility, composition accuracy, and repeatability of gradient profiles.

AbstractMiniaturization and optimization of the solvent delivery system, mixing device, and detection system for gradient elution at few μl/min is the most important objective of instrumental development in microHPLC using packed capillary columns. Instrumental solutions and evaluation of the performence of a dedicated system for automatic gradient elution with packed capillary columns are reported. Retention time precision shown buy the system results in an RSD of 0.20–0.52% for a PAH model mixture eluted under gradient conditions at few μl/min. Compositional accuracy of gradient profiles is also demonstrated.

Endocrinologically- and socially-dependent volatile constituents of female mouse urine, identified in a previous study, were tested for their capability to accelerate puberty and extend the estrous period in young females. Several volatile ketones advanced puberty by approximately three days and extended the period of vaginal cornification in 55–75% of exposed females. High concentrations of these substances were capable of overriding the known puberty-delaying chemosignals. Volatile cyclic enol ethers were also effective in extending estrus, but not puberty acceleration.

The volatile compounds identified by combined gas chromatography-mass spectrometry inMicrotus pinetorum urine include alcohols, aldehydes, hydrocarbons, ketones, nitriles, and pyrazines. Several lactone derivatives were found to be characteristic urinary substances of this species. Ovariectomy depressed concentrations of only five out of a great number of profile constituents. Elevating estrogen levels (by exposing females to male-soiled bedding or treating them with estradiol) tends to depress the urinary concentration of a number of selected volatiles. Estrogen implantation provoked a periodic increase in the level of three compounds (nonanal, benzal-dehyde, and an unidentified substance). The volatile profile of castrate male urine was similar to that of intact male urine. Female urine contained γ-octanoic lactone and two pyrazine derivatives in higher concentrations andp-methyI-propenylbenzene in a lower concentration, when compared to male urine. No qualitative differences between the urinary profiles of males and females were observed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUse of capillary supercritical fluid chromatography and microcolumn liquid chromatography for the determination of nonvolatile organics in aqueous environmental samplesClaudio. Borra, Franca. Andreolini, and Milos. NovotnyCite this: Anal. Chem. 1989, 61, 11, 1208–1210Publication Date (Print):June 1, 1989Publication History Published online1 May 2002Published inissue 1 June 1989https://pubs.acs.org/doi/10.1021/ac00186a006https://doi.org/10.1021/ac00186a006research-articleACS PublicationsRequest reuse permissionsArticle Views48Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

AbstractA method for the determination of individual free and conjugated bile acids in serum using microcolumn liquid chromatography coupled with a laser‐induced fluorescence detector is described. Bile acids are separated into free/glycine‐conjugate and taurine‐conjugate fractions using a Sep‐Pak SIL cartridge. The taurine‐conjugated bile acid fraction is subjected to enzymatic hydrolysis. Subsequently, free and conjugated bile acids are labeled using 4‐(bromomethyl)‐7‐methoxycoumarin as a fluorogenic reagent, producing stable derivatives that can be excited by the 325 nm line of a He/Cd laser. Prior to their fluorimetric detection, the individual components of a bile acid serum profile are separated by reversed‐phase microcolumn liquid chromatography.

Slurry-packed fused-silica microcolumns of 250 μm I.D., are characterized for use in high-performance liquid chromatographic studies of proteins. The present work utilizes the reversed-phase and size-exclusion chromatographic modes for the separation of standard protein mixtures. A 5-μm, 300-Å octyl material is utilized for the reversed-phase studies, and the size-exclusion studies are accomplished with 5-μm diol material of 60-, 100- and 300-Å pore sizes. Column efficiency and packing reproducibility, as well as sample capacity in a micropreparative mode, are discussed. In addition, the inherent mass sensitivity of a microcolumn liquid chromatography system as applied to protein detection is demonstrated.

The volatile fraction of urinary metabolites was investigated chromatographically at five different stages of the natural estrous cycle. A very substantial endocrine dependency has been noted for 11 compounds: 4 ketones, 2 acetate esters, 3 dihydrofuran isomers, dehydro-exo-brevicomin, and 2,5-dimethylpyrazine. The compounds were structurally verified through combined gas chromatography/mass spectrometry.

Mouse urine samples from different pregnancy and lactation periods were examined by capillary gas chromatography to assess variations in the volatile signals that may affect the endocrine function of other females. Statistically significant changes in the excretion of certain urinary volatiles were observed; from 26 readily quantifiable constituents, 14 appear to be under the endocrine control. These selected components, positively identified through mass spectrometry and retention data, and the synthetic standards are ketones, unsaturated alcohols, esters, and cyclic vinyl ethers.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEstrogen conjugates in late-pregnancy fluids: extraction and group separation by a graphitized carbon black cartridge and quantification by high-performance liquid chromatographyFranca. Andreolini, Claudio. Borra, Federica. Caccamo, Antonio. Di Corcia, and Roberto. SamperiCite this: Anal. Chem. 1987, 59, 13, 1720–1725Publication Date (Print):July 1, 1987Publication History Published online1 May 2002Published inissue 1 July 1987https://doi.org/10.1021/ac00140a029RIGHTS & PERMISSIONSArticle Views255Altmetric-Citations67LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (687 KB) Get e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and evaluation of slurry-packed capillary columns for normal-phase liquid chromatographyFranca. Andreolini, Claudio. Borra, and Milos. NovotnyCite this: Anal. Chem. 1987, 59, 19, 2428–2432Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://doi.org/10.1021/ac00146a023RIGHTS & PERMISSIONSArticle Views197Altmetric-Citations37LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (620 KB) Get e-Alerts Get e-Alerts

High chromatographic efficiency demonstrated by slurry-packed capillary columns in liquid chromatography was crucial in the separation of non-volatile polycyclic aromatic sulfur heterocyclic compounds, isolated from a solvent-refined coal sample. Mass-spectral characterization of the trapped components revealed the presence of numerous isomers of the parent and alkylated polycyclic compounds with five- to nine-ring structures. In addition, fluorescence emission spectra, acquired with an intensified photodiode-array detector, yielded information concerning the shape of the molecules whenever authentic compounds were available.