การแยก R/S-กรดไขมันแอลฟาไฮดรอกซีเอสเทอร์ด้วยแก๊สโครมาโตกราฟี

Name: จินดารัตน์ โตกมลธรรม

Organization : มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

keyword: Enantiomer

; Diastereomer

; Gas chromatography

; Hydroxy fatty acid ester

; Resolution

Abstract: Gas chromatographic separations of R/S-?-hydroxy fatty acid esters (R/S-AHFAs) areperformed by using both direct and indirect approaches. By using direct approach, shortchain R/S-AHFA methyl esters are well separated on CYDEX-B chiral column but theresolution becomes poorer as the carbon chain length of AHFA is increased. This isprobably due to increasing of acid chain length, which leads to the largeness of AHFAmolecule; therefore, it is difficult for long chain AHFAs to enter the cyclodextrin cavity.However, resolution is improved when the R/S-AHFAs are converted into 2-pentyl,2-hexyl, 2-heptyl or 2-octyl diastereomeric esters.By using derivatization or indirect approach, longer chain R/S-AHFAs are also wellresolved as their diastereomers with 2-pentanol, 2-hexanol, 2-heptanol, 2-octanol ormenthyl on BP-1 (non-polar phase) or Rtx-2330 (very polar phase) capillary columns.The shorter chain length of the alcohol tends to give lower resolution factor (RS) on thesame column. The longest chain length of alcohol used in this study is 2-octanol and itsester shows the highest RS on the Rtx-2330 capillary column.Thus, the four thermodynamically related column constants (a, b, c and d) of Eq. 1 forR-and S-AHFA standard octyl esters are determined.Ink=a+bz+c/T+dz/T Eq. 1where k is the retention factor, z is carbon number or equivalent chain length (ECL),T is the absolute temperature and a, b, c and d are thermodynamically related constants.This equation is used to predict the unadjusted retention time (tR) of R- and S-AHFAoctyl esters at various temperatures. The predicted values are in well agreement with theexperiment values. The largest difference between the experimental and predictedvalues is 0.96 %. The above equation can also be applied to identify and determine theconfiguration of AHFAs derived from natural wool wax without using a standardAHFA as a reference. Results found that AHFAs in wool wax are R-isomers. Also,wool wax contained, beside those reported by Horn et al. (Journal of the ChemicalSociety p. 177, 1954), some odd chain carbon numbers, 12-methyl tridecanoate, 14-methyl pentadecanoate and 16-methyl heptadecanoate are found. A trace amount of S-?-hydroxy pentadecanoate (30.2% enantiomeric excess in R) is detected. Thisinvestigation seems to be a convenient approach for simultaneous separation ofR/S-AHFAs and accurate determination of their configurations in a single analysis without any reference.

มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

Address: กรุงเทพมหานคร (Bangkok)

Email: info.lib@mail.kmutt.ac.th

Name: Assoc.Prof. Kanit Krisnangkura

Role: Supervisor

Created: 2546

Issued: 2005-11-08

Modified: 2006-05-09

วิทยานิพนธ์/Thesis

ISBN: 9744563753

CallNumber: BIT456

tha

DegreeName: วิทยาศาสตรมหาบัณฑิต

Level: ปริญญาโท

Descipline: เทคโนโลยีชีวภาพ

Grantor: มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี

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