“Kovats retention index”的意思、由来-开放百科全书

词条

Kovats retention index

释义

Expression
References

In gas chromatography, Kovats retention index (shorter Kovats index, retention index; plural retention indices) is used to convert retention times into system-independent constants. The index is named after the Hungarian-born Swiss chemist Ervin Kováts, who outlined this concept during the 1950s while performing research into the composition of the essential oils.^[1]

The retention index of a certain chemical compound is its retention time normalised to the retention times of adjacently eluting n-alkanes. While retention times vary with the individual chromatographic system (e.g. with regards to column length, film thickness, diameter, carrier gas velocity and pressure, and void time), the derived retention indices are quite independent of these parameters and allow comparing values measured by different analytical laboratories under varying conditions. Tables of retention indices can help identify components by comparing experimentally found retention indices with known values.^[2] ^[3] ^[4]

Expression

The method interpolates peak time between bracketing n-alkanes. The value of Kovats index is usually represented by , in mathematical expressions. It applies to organic compounds. For isothermal chromatography, the Kovats index is given by the equation

where I is the Kovats retention index,

n is the number of carbon atoms in the smaller n-alkane,

N is the number of carbon atoms in the larger n-alkane, and

t_peak is the retention time of the peak,

t_n & t__n+1 is the retention time of the n-alkanes bracketing the peak,

t₀ is the void time related to column length and average velocity ū.

For temperature programmed chromatography, ASTM method D 6730 defines the Kovats index equation

Measured Kovats retention index values can be found in ASTM method D 6730 databases.

An extensive database is compiled by NIST (https://webbook.nist.gov/chemistry/).

Hydrocarbon Kovats indices were measured by Axel Lubeck and Donald Sutton in the J.o.Hi.Res.Chro (1982,1983).

References

1. ^Institute of Chemical Sciences and Engineering, KOVATS Ervin, Prof. Hon.{{dead link|date=October 2014}}
2. ^{{cite journal | last = Kovats | first = E. | title = Gas-chromatographische Charakterisierung organischer Verbindungen. Teil 1: Retentionsindices aliphatischer Halogenide, Alkohole, Aldehyde und Ketone | volume = 41 | pages = 1915–32 | year = 1958 | journal = Helv. Chim. Acta | doi = 10.1002/hlca.19580410703 | issue = 7}}
3. ^{{GoldBookRef |title = retention index, I in column chromatography |file = R05360}}
4. ^Retention index guide

5 : Chromatography|Analytical chemistry|Hungarian inventions|Hungarian inventors|Hungarian scientists

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