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Compound Analysis (compound + analysis)
Selected AbstractsReducing glycerophosphocholine lipid matrix interference effects in biological fluid assays by using high-turbulence liquid chromatographyRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2008Lihong Du Matrix interferences can severely affect quantitative assays of biological samples when electrospray ionization (ESI) is employed with liquid chromatography/tandem mass spectrometry (LC/MS/MS). A major source of matrix interferences for plasma sample analyses is the presence of glycerophosphocholine (GPCho) lipids. The efficiency of online high-turbulence liquid chromatography (HTLC) extraction for eliminating these lipids is evaluated and the interfering effects of endogenous lipids on human plasma assays are measured for pharmaceutical compounds having a wide variety of chemical properties. It is found that GPCho lipids, represented by 16:0, 18:1 and 18:0 LPC (lysophosphatidylcholine) and 16:0-18:2 PC, cause variations for hydrophobic compound analyses even when optimal online HTLC extraction conditions are employed. The efficiency for lipid removal depends on the organic content of the transfer solvent, but turbulent flow loading has no significant effect. Copyright © 2008 John Wiley & Sons, Ltd. [source] Thin-layer chromatography/electrospray ionization triple-quadrupole linear ion trap mass spectrometry system: analysis of rhodamine dyes separated on reversed-phase C8 plates ,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2005Michael J. Ford Abstract The direct analysis of separated rhodamine dyes on reversed-phase C8 thin-layer chromatography plates using a surface sampling/electrospray emitter probe coupled with a triple-quadrupole linear ion trap mass spectrometer is presented. This report represents continuing work to advance the performance metrics and utility of this basic surface sampling electrospray mass spectrometry system for the analysis of thin-layer chromatography plates. Experimental results examining the role of sampling probe spray end configuration on liquid aspiration rate and gas-phase ion signal generated are discussed. The detection figures-of-merit afforded by full-scan, automated product ion and selected reaction monitoring modes of operation were examined. The effect of different eluting solvents on mass spectrum signal levels with the reversed-phase C8 plate was investigated. The combined effect of eluting solvent flow-rate and development lane surface scan rate on preservation of chromatographic resolution was also studied. Analysis of chromatographically separated red pen ink extracts from eight different pens using selected reaction monitoring demonstrated the potential of this surface sampling electrospray mass spectrometry system for targeted compound analysis with real samples. Copyright © 2005 John Wiley & Sons, Ltd. [source] Different postharvest dehydration rates affect quality characteristics and volatile compounds of Malvasia, Trebbiano and Sangiovese grapes for wine productionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004Andrea Bellincontro Abstract Experiments were carried out using an innovative technology for dehydration based on the passage of air through a tunnel. It was possible to study the postharvest behaviour, at different rates of dehydration, of Malvasia, Trebbiano and Sangiovese grapes. Malvasia and Trebbiano grapes were picked with 17.5% SSC (soluble solids content), while Sangiovese grapes were harvested fully ripe with 26% SSC. All the grapes, in different experiments, were placed in the tunnel with an air speed of 1,1.5 m s,1, 42% RH (relative humidity) and a temperature of 21 °C. After 18 days the weight loss was 50 and 34% respectively in tunnel-treated Malvasia and Trebbiano grapes, while it was only 13,14% in control grapes (outside the tunnel: RH around 65% and temperature about 20 °C without ventilation). The SSC rose to 35 and 27% respectively in tunnel-treated Malvasia and Trebbiano grapes compared with 23 and 21% respectively in control grapes. In the case of Sangiovese grapes, after 7 days (the end of treatment) the weight loss was 20.5% in tunnel-treated grapes and 10.5% in control grapes. The SSC rose to 32% and the acidity increased from 4.8 to 5.8 g l,1 in tunnel-treated grapes compared with 29% and 5 g l,1 respectively in control grapes. Total phenols and anthocyanins almost doubled in tunnel-treated Sangiovese berries. Volatile compound analysis revealed a higher ethanol concentration in all tunnel-treated grapes but a lower concentration of ethyl acetate and acetic acid. Copyright © 2004 Society of Chemical Industry [source] The evolution of volatile compounds profile of "Toscano" dry-cured ham during ripening as revealed by SPME-GC-MS approach,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2010C. Pugliese Abstract The volatile compounds profile is an important feature for the characterization of dry-cured hams. Some minor typical Italian products, such as ,Toscano' ham, have been poorly studied in regards to their composition of volatile compounds. In this article, we studied the evolution of the aromatic profile of ,Toscano' dry-cured ham by solid-phase microextraction-gas chromatographic-mass spectrometry (SPME-GC-MS) with ripening. Ten right thighs were cured according to the ,Toscano' PDO protocol, sampled at 0, 1, 3, 6 and 12 months and submitted to volatile compounds analysis by SPME with a Divinylbenzene (DVB)/Carboxen/Polydimethylsiloxane (PDMS) 75-µ Stable Flex fibre. An Agilent 5975C mass selective detector (MSD) spectrometer with electron ionization (EI) source operating in scan mode within the m/z 29,350 range was used for data collection. Seven internal standards, either deuterium labeled or absent in the specimens and chosen to represent low or high boiling esters, alcohols, acids or phenols, were added to the homogenized samples and used to normalize the SPME fibre response to account for response changes upon wearing. Linear calibrations were obtained in this way for selected representative compounds. Over 60 compounds belonging to esters, aldehydes, organic acids, ketones and alcohols were identified by comparison with spectral libraries and Kovats indices. Aldehydes were the most represented chemical family, followed by organic acids, alcohols, ketones and esters. The aldehydes and ketones increased during the first 3 months, when the larger formation of volatiles occurred. For other families, the evolution over time was less evident. The principal component and discriminant analyses of the aromatic profile were effective in classifying the hams at 0, 6 or 12 months of ripening while for 1 and 3 months' samples a partial overlapping was shown. These results represent the first characterization of ,Toscano' ham and may constitute the basis to identify the best ripening time and define an analytical quality standard for this typical ham. Copyright © 2010 John Wiley & Sons, Ltd. [source] | ||||||||||