Ionic liquids as novel stationary phases in gas liquid chromatography: Inverse or normal isotope effect?

Schmarr, Hans‐Georg; Slabizki, Petra; Müntnich, Sabrina; Metzger, Carmen S.; Gracia-Moreno, Elisa

doi:10.1016/j.chroma.2012.11.010

Cited by 29 publications

(22 citation statements)

References 60 publications

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“…However, the position of the deuterium in the molecule also influences the retention time shift [25]. It has been shown that deuterium in the aliphatic part of the molecule plays a more important role in GC separation than deuterium at the aromatic ring [26,27]. The shift of deuterated analytes on nonpolar stationary phases to lower retention times is called inverse isotope effect.…”

Section: Isotope Effectmentioning

confidence: 97%

“…The shift of deuterated analytes on nonpolar stationary phases to lower retention times is called inverse isotope effect. On polar stationary phases, such as diglycerol [28] or ionic liquids [27] and in adsorption chromatography [29] normal isotope effects, also called direct isotope effect, can be observed with the deuterated analyte eluting after the hydrogen containing compound. The terms inverse and normal isotope effect are used according to the term employed in discussing the vapor pressure isotope effects (VPIE) [30].…”

Section: Isotope Effectmentioning

confidence: 99%

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Quantitative Analysis

Dettmer-Wilde

Engewald

2014

Practical Gas Chromatography

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Section: Isotope Effectmentioning

confidence: 97%

Section: Isotope Effectmentioning

confidence: 99%

Quantitative Analysis

Dettmer-Wilde

Engewald

2014

Practical Gas Chromatography

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“…The labelled internal standard used to quantify each target analyte, respective retention time and the target and qualifier ions used for SIM and relative percentages are given in Table 3.1. Schmarr et al (2012) reported an inverse isotope effect whereby the heavier deuterated compounds elute prior to their non-labelled counterparts as was also observed in our study.…”

Section: Mango Volatile Analysis Methods and Validationsupporting

confidence: 64%

Lenticel discolouration, under-skin browning and resin canal disorder in Australian mango fruit cultivars

San¹

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Lenticel discolouration (LD), under-skin browning (USB), and resin canal disorder (RCD) are three fruit skin disorders of concern to the Australian mango industry. LD is confined to lenticels on the fruit skin. It was suspected that irradiation may differentially induce LD on cvs. 'B74', 'Honey Gold', 'Kensington Pride', and 'R2E2' fruit. Irradiation at 0.5 kGy significantly (P≤0.05) increased LD and delayed the loss of green skin colour of all four cultivars. There was generally no significant differences (P>0.05) between 0.5 ('commercial' dose) and 1.0 kGy ('upper limit' dose).The least pronounced effect was on cv. 'Honey Gold'. Irradiation also diminished aroma volatiles production by cvs. 'Kensington Pride' and 'R2E2'. Examination of the morphology of LD showed it in tissue sections as browning of sub-lenticellular cells around lenticel cavities. No such browning was evident in sub-lenticellular cells around non-coloured lenticel cavities. Coloured polymerised phenolic compounds appeared accumulate in the cell wall and in the cytoplasm of sub-lenticellular cells around the cavities of discoloured lenticels.USB is a physiological disorder evident as spreading grey -brown sub-surface lesions in cv. 'Honey Gold' mango fruit. In contrast, RCD in cv. 'Kensington Pride' mango fruit is evident as ramifying dark brown sub-surface resin canals. These two largely cv. specific browning disorders were compared and contrasted at the cellular level. USB was characterised by dark brown surrounding parenchyma cells around the epithelial cells that line resin ducts. This disorder involves starch retention as well as deposition of phenolic compounds in parenchyma cells surrounding the epithelial cells of resin ducts. In contrast, RCD was distinguished by localised browning inside resin duct lumens. The browning process evidently involved accumulation of polymerised phenolics.Polyphenol oxidase and peroxidase enzymes were determined by tissue printing to be associated with both USB and RCD browning.The effect of harvest time over the diurnal cycle was investigated with regard to the propensity of cv. 'Honey Gold' fruit to develop USB. USB expressed in postharvest is related to the cumulative interaction of physical (viz., vibration) and physiological (viz., chilling) stresses. Fruit harvested during the day were relatively more susceptible to developing USB than were those picked at night.The higher USB incidence in the afternoon harvest was related to temporally variable sap phytoxicity. An important contributory factor to greater afternoon sap phytoxicity was concomit ant increases in the concentrations of volatiles in the sap and, especially, in the non-aqueous sap phase.Changing from day to night and early morning harvesting afforded reduced incidence and severity of USB on cv. 'Honey Gold' fruit. v Li, G.Q., Gupta, M ., San, A.T., Joyce, D.C., Hofman, P.J., M acnish, A.J., M arques, J., 2016.Postharvest treatment effects on 'B74' mango fruit lenticel discolouration after irradiation. Acta Horticulturae (ISHS) 1111...

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“…However, these authors could not achieve a sufficient chromatographic resolution of labeled and unlabeled compounds . With respect to their optimization for routine analysis, most probably, the relatively high oven‐heating rate applied (5 vs. 2°C/min in our study) favors the entropy rather than the enthalpy contribution of the underlying separation process .…”

Section: Resultsmentioning

confidence: 81%

Headspace solid‐phase microextraction and gas chromatographic analysis of low‐molecular‐weight sulfur volatiles with pulsed flame photometric detection and quantification by a stable isotope dilution assay

Ullrich

Neef

Schmarr

2017

J of Separation Science

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Low-molecular-weight volatile sulfur compounds such as thiols, sulfides, disulfides as well as thioacetates cause a sulfidic off-flavor in wines even at low concentration levels. The proposed analytical method for quantification of these compounds in wine is based on headspace solid-phase microextraction, followed by gas chromatographic analysis with sulfur-specific detection using a pulsed flame photometric detector. Robust quantification was achieved via a stable isotope dilution assay using commercial and synthesized deuterated isotopic standards. The necessary chromatographic separation of analytes and isotopic standards benefits from the inverse isotope effect realized on an apolar polydimethylsiloxane stationary phase of increased film thickness. Interferences with sulfur-specific detection in wine caused by sulfur dioxide were minimized by addition of propanal. The method provides adequate validation data, with good repeatability and limits of detection and quantification. It suits the requirements of wine quality management, allowing the control of oenological treatments to counteract an eventual formation of excessively high concentration of such malodorous compounds.

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Ionic liquids as novel stationary phases in gas liquid chromatography: Inverse or normal isotope effect?

Cited by 29 publications

References 60 publications

Quantitative Analysis

Quantitative Analysis

Lenticel discolouration, under-skin browning and resin canal disorder in Australian mango fruit cultivars

Headspace solid‐phase microextraction and gas chromatographic analysis of low‐molecular‐weight sulfur volatiles with pulsed flame photometric detection and quantification by a stable isotope dilution assay

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