Explanation of Retention Index function
Since the introduction of version VCF 14.1, Kovats Retention Indices (Kovats RI) of volatile compounds are given. The data are derived from literature. The results are summarized for 4 types of gas chromatographic columns (in increasing polarity): DB-1, DB-5, DB-17 and DB-Wax (*).
Estimated values are indicated as […]. Values too far from the average or expected values, are indicated as …?
Unless no other data are available, estimated and unreliable values are not used for computing average values.
The RI data can be obtained in two ways:
- By using the Search - Retention Index menu button.
A search screen comes up in which you have to select a column type and then enter a Retention Index value. After pressing [search] there will be a list with compounds and corresponding Kovats RI in the range of the selected value ± 25 units
- By selecting a compound.
In the data for this compound the Retention Indices on the four types of columns are given as far as introduced at that moment. When available, also odour values are presented.
The RI values are obtained in principle from the same literature sources as for the compound occurrences. Additional data were obtained from databases such as: the book of Robert P. Adams Identification of essential oil components by gas chromatography/mass spectrometry
(ISBN-13: 978-1932633214), from the website of Terry E. Acree et al. at www.flavornet.org
and from the Citrus Flavor Database www.crec.ifas.ufl.edu/rouseff/
. RI values on four types of GC-columns are compiled (these are indicated as similar to DB-1, DB-5, DB-17 and DB Wax).
The average RI values are calculated from all RI values found for a compound on a given type of GC-column. Some values are presented between brackets [ ]. These are values estimated by Acree and will only be shown when no other RI value for a compound is found.
The compilation of Kovats RI will be continuously updated from version VCF 14.1 onwards. These new values in the database will be published immediately, making it a growing and changing entity.
(*) The naming of the column types is only meant as an indication of the polarity.
||OV-1, OV -101, SE-30
||CPSil 5, DB-1, HP-1, RTx-1, etc.
|OV-73, SE-52, SE-54
||CPSil 8, DB-5, HP-5, RTx-5, etc.
||DB-17, HP-50, RTx-50, AT-1701
||CPWax 52, DB-Wax, FFAP