Kovat s retention index

What is the Kovat s retention index for each of these hydrocarbons ... 

Kovat s retention index for a normal alkane is 100 times the number of carbons thus... 

To find Kovat s retention index for isobutane, we use equation 12.29. 

Kovat s retention index (p. 575) liquid-solid adsorption chromatography (p. 590) longitudinal diffusion (p. 560) loop injector (p. 584) mass spectrum (p. 571) mass transfer (p. 561) micellar electrokinetic capillary chromatography (p. 606) micelle (p. 606) mobile phase (p. 546) normal-phase chromatography (p. 580) on-column injection (p. 568) open tubular column (p. 564) packed column (p. 564) peak capacity (p. 554)... 

Kovat s retention index a means for normalizing retention times by comparing a solute s retention time with those for normal alkanes, (p. 575)... 

Kovat s retention indexes analychem Procedure to identify compounds in gas chromatography the behavior of a compound Is Indicated by Its position on a scale of normal alkane values (for example, methane = 100, ethane = 200). ko-vats ri ten-... 

RT retention time on DB-5 capillary column AI arithmetic retention index KI Kovat s retention index CAS chemical abstracts service number MF molecular formula FW formula weight MSD LIB entry number in library CN chemical name... 

Kovat s retention index I Used to compare therelative retention of compounds regardless of column and laboratory through the use of the following equation ... 

Equation 4.1 describes the Rohrschneider-McReynolds system in terms of the five probes and their corresponding phase constants namely, benzene (X ), butanol (Y ), 2-pentanone (Z ), nitropropane (U ), and pyridine (S ) with the overall difference in the Kovats retention index (AI). 

The samples were analyzed by capillary gas chromatography and gas chromatography/mass spectrometry (GC/MS). Identifications were verified by comparing the component s mass spectmm and experimental retention index (I) with that of an authentic reference standard. The retention system proposed by Kovats (12) was utilized. When standards were not available the identifications were considered tentative. 

Figure 2.22 Graphical measurement of Kovats retention index (/= lOOn ) on a column in the isothermal mode. The number of equivalent carbons n, is found from the logarithm of the adjusted retention time t of X. The chromatogram corresponds to the injection of a mixture of 4 n-alkanes and two aromatic hydrocarbons. The values in italics match the retention times given in seconds. By injecting periodically this mixture the modifications to the Kovats indexes of these hydrocarbons permits the following of the column s performance. The calculations for retention indexes imply that the measurements were effected under isothermal conditions. With temperature programming they yield good results to the condition to adopt an adjusted formula, though this entails a reduction in precision.

In a GC experiment a mixture of n-alkanes (up to n carbon atoms, where n represents a variable number) and butanol (CHj CH2 CH2 CH2 OH) were injected onto a column maintained at a constant temperature and whose stationary phase was of silicone-type material. The equation of the Kovats straight line derived from the chromatogram is log t = 0.39n — 0.29 (where the adjusted retention time is in seconds). The adjusted retention time of butanol is 168 s. If it is known that the retention index for butanol on a column of squalane is 590 s then deduce its corresponding McReynolds constant upon this column. 

Retention indices, RI method of expressing relative retention characteristics of a wide range of components, the most well known being the Kovat s index. This compares log retention time of an unknown compound with log retention times of the -alkanes eluted before and after. 

Retardation factor in TLC, PC Corrected retardation factor Retention index, Kovat s RI Resolution between adjacent peaks Signal output from detector Separation number Stationary phase Time... 

Mass spectrum (complete spectrum) and Kovat s GLC retention Index of all compounds listed are consistent with that of authentic samples, except for e. 

Fragmentation of these compounds are also similar. Therefore assignment of the individual component requires additional information, linear retention index or Kovat s index and confirmation with authentic standards. Manual interpretation of the mass spectrum is some time needed, when there is no fitted matching. Isotope abundance is very useful to postulate the identity of molecule or fragment. 

A 1.1 The logarithmic Kovats Retention Index is a gas chromatographic parameter characteristic of a solute s relative retention on a specified liquid phase at a specified (isothermal) temperature. It is a very useful tool in the qualitative identification of chromatographic peaks. 

A uniform system of retention classification according to a solute s relative location between a pair of homologous reference compounds on a specific column under specific conditions. It compares the time a compound is eluting from the column to the times of a set of standard compounds. The most common set of compounds used for retention indices are hydrocarbons typically from C5 to C30, separated in the order of boiling points, Kovats index. 

---