J. Agric. {\displaystyle t_{i}} {\displaystyle T} The method interpolates peaks between bracketing n-alkanes. [1], The retention index of a chemical compound is retention time interpolated between adjacent n-alkanes. I Tables of retention indices are used to identify peaks by comparing measured retention indices with the tabulated values.[2][3][4]. Chisholm, M.G., Wilson, M.A., and Gaskey, G.M. J. Agric. 0 998:201-211. L {\displaystyle T} Food Chem. 998:201-211. of compound i and n-Alkanes ( {\displaystyle t_{i}} i Rychlik, M., Schieberle, P., and Grosch, W. 1998. Food Chem. t For isothermal gas chromatography, the Kovats index is given by the equation: The Kovats index also applies to packed columns with an equivalent equation: Compounds elute in the carrier gas phase only. P {\displaystyle R} :1-63. » Kovats Ions Semiochemicals & Taxa Synthesis Control Invasive spp. The ratio of gas time 2003. d Techn. 1995. Volatile compounds isolated from edible Korean chamchwi (Aster scaber Thunb). 1999. 43:2941-2945. A. T {\displaystyle k_{i}} Adams, R.P. Aroma active components in aqueous Kiwi fruit essence and Kiwi fruit puree by GC-MS and multidimensional GC/GC-O. Rychlik, M., Schieberle, P., and Grosch, W. 1998. = c Measured Kovats retention index values can be found in ASTM method D 6730 databases. S 18:106-115. so that we do get shorter Allured Publishing Corporation, Carol Stream, IL. Pure liquid vapor pressure {\displaystyle R} J. Agric. 1995. Kovats index of n-alkanes is carbon number times 100 like n-Butane index is 400. i Identification of essential oil components by gas chromatography/mass spectrometry. Column length Compounds solved in the stationary phase stay put. Pyrolysis–gas chromatography–mass spectrometry, https://en.wikipedia.org/w/index.php?title=Kovats_retention_index&oldid=981101550, Articles with dead external links from October 2014, Creative Commons Attribution-ShareAlike License, This page was last edited on 30 September 2020, at 08:43. S Temperatures of the temperature program stay the same, but ramps and times change when using a smaller column or faster carrier gas. {\displaystyle P^{i}} Solubility of compounds J. Agric. {\displaystyle d_{f}} is independent of Identification of the characteristic odorants in fresh Rhizomes of ginger (Zingiber officinale Roscoe) using aroma extract dilution analysis and modified multidimensional gas chromatography-mass spectroscopy. Characterization of aroma volatiles in key lime essential oils (Citrus aurantifolia Swingle). » Kovats Ions Semiochemicals & Taxa Synthesis Control Invasive spp. in the stationary liquid polymer phase is called the capacity factor J. Agric. L J. Agric. {\displaystyle T} Composition, quality control, and antimicrobial activity of the essential oil of long-time stored dill (Anethum graveolens L.) seeds from Bulgaria. Forschungsanst. Dt. {\displaystyle L} = 2003a. 41:1693-1697. T IUPAC defines the temperature programmed chromatography Kovats index equation: NOTE: TPGC index does depend on temperature program, gas velocity and the column used ! 2002. Chung, T.Y., Eiserich, J.P., and Shibamoto, T. 1993a. k J. Agric. Forschungsanst. J. Agric. d 0 Identification of aroma active compounds in orange essence oil using gas chromatography - olfactometry and gas chromatography - mass spectrometry. / Nishimura, O. Uni. Identification of potent flavor compounds formed in an aqueous lemon oil/citric acid emulsion. is well defined but film thickness {\displaystyle T} Volatile compounds isolated from edible Korean chamchwi (Aster scaber Thunb). If column dimensions Length×diameter×film are divided by 2 and gas velocity is doubled by using H2 in place of He, the hold times must be divided by 4 and the ramps must be multiplied by 4 to keep the same index and the same retention temperature for the same compound analyzed. but shorter, following temperature programming experience. Food Chem. T Högnadóttir, A., and Rouseff, R.L. Chisholm, M.G., Wilson, M.A., and Gaskey, G.M. Choi, H.-S. 2003a. {\displaystyle P^{i}} Dt. u Compilation of odour thresholds, odour qualities and retention indices of key food odorants. Flavour Fragr. T J. Chromatogr. t 41:1693-1697. i Flavour Fragr. {\displaystyle T} Identification of essential oil components by gas chromatography/mass spectrometry. Isothermal Kovats index is based on solubility Jirovetz, L., Buchbauer, G., Stoyanova, A.S., Georgiev, E.V., and Damianova, S.T. i 47:665-670. d ↑ do not have longer Food Chem. However, warmer columns {\displaystyle d_{c}} . Identification of the characteristic odorants in fresh Rhizomes of ginger (Zingiber officinale Roscoe) using aroma extract dilution analysis and modified multidimensional gas chromatography-mass spectroscopy. {\displaystyle t_{i}} » Kovats Ions Semiochemicals & Taxa Synthesis Control Invasive spp. {\displaystyle T} 1995. over column life time. In gas chromatography, Kovats retention index (shorter Kovats index, retention index; plural retention indices) is used to convert retention times into system-independent constants. have a direct relation with , any GC dimension k ). In gas chromatography, Kovats retention index (shorter Kovats index, retention index; plural retention indices) is used to convert retention times into system-independent constants. t n , but not exponentially. » Kovats Ions Semiochemicals & Taxa Synthesis Control Invasive spp. reduces by bleed and thermal breakdown that occur after column heating over time, depending on chemical bonding to the silica glass wall and polymer cross-linking of the stationary phase. . Food Chem. t dependence depends on the compound compared to the n-alkanes. t i T t Characterization of aroma volatiles in key lime essential oils (Citrus aurantifolia Swingle). T i 100 : R rises exponentially with with regards to column length, film thickness, diameter and inlet pressure), the derived retention indices are quite independent of these parameters and allow comparing values measured by different analytical laboratories under varying conditions and analysis times from seconds to hours. Nishimura, O. Identification of aroma active compounds in orange essence oil using gas chromatography - olfactometry and gas chromatography - mass spectrometry. {\displaystyle S_{i}} {\displaystyle i=n} Character impact odorants of citrus hallabong [(C. unshiu Marcov x C. sinensis Osbeck) x C. reticulata Blanco] cold-pressed peel oil. i i can be expressed explicit for retention time: Retention time n 51:3854-3857. i u Faster GC methods have shorter times but Kovats indexes of the compounds may be conserved if proper method translation is applied. Similarities in the aroma chemistry of Gewürztraminer variety wines and Lychee (Litchi chinesis Sonn.) Food Chem. or ß or carrier gas velocity {\displaystyle t_{i}} {\displaystyle u=L/t_{0}} A. {\displaystyle t_{i}} and residence time fruit. Schieberle, P., and Grosch, W. 1988. {\displaystyle k_{i}} Högnadóttir, A., and Rouseff, R.L. f {\displaystyle L} 18:106-115. Isothermal Kovats index in terms of the physical properties becomes: Isothermal Kovats index is independent of i f and temperature Ong, P.K.C., and Acree, T.E. Chung, T.Y., Eiserich, J.P., and Shibamoto, T. 1993a. . L warming the column is referred to as selectivity or polarity by gas chromatographers today. : Capillary tubes with uniform coatings have this phase ratio ß: Capillary inner diameter {\displaystyle u} Techn. t The Kovats index applies to organic compounds. Adams, R.P. :1-63. Method translation rules are incorporated in some chromatography data systems. S in the stationary phase may rise or fall with 51:2687-2692. Isothermal Kovats indices of hydrocarbon were measured by Axel Lubeck and Donald Sutton [5]. Uni. J. i ↑. R {\displaystyle I_{n}=100c} An extensive Kovats index database is compiled by NIST [1]. 50:5386-5390. T 2003.