Biomedical subjects

Kornkanok Aryusuk

Publications and source records attributed to Kornkanok Aryusuk.

3 recordsLinked to original sources

PubMed2006

Prediction of gas chromatographic retention times of esters of long chain alcohols and fatty acids.

The linear free energy of solution (DeltaG) relationship (DeltaG=DeltaGo+zdeltaG) for compounds of different carbon atoms (z) in the same homologous series is expanded and modified to cover compounds with two different hydrocarbon side chains. The expanded equation is successfully used to predict the retention times (tR) of standard esters of long chain alcohols and fatty acids of different chain lengths in both isothermal and temperature-programmed gas chromatography (TPGC). Approximately 90% of the 125 predicted tR values have a difference of less than 1.00% from the actual tR and the highest difference is 1.26%. Two different temperature gradients in TPGC are tested. The expanded equation can be used to forecast the tR of TPGC with good accuracy. The highest difference is +/-1.40% and +/-1.00% for the temperature gradients of 2 degrees C and 4 degrees C/min, respectively. However, the increments in free energy per carbon atom (zdeltaG) of the alcohol and acid are approximately equal but have slightly different temperature sensitivities. Therefore, it is very difficult to separate esters of different acid and alcohol chain length but with the same total carbon numbers. Furthermore, the difference in temperature sensitivities for the acid and alcohol side chains renders them to be inversely eluted at different temperatures.

Algorithms↗

PubMed2004

Molecular interconversion behaviour in comprehensive two-dimensional gas chromatography.

Comprehensive two-dimensional gas chromatography (GC x GC) is shown to provide information on dynamic molecular behaviour (interconversion), with the interconversion process occurring on both columns in the coupled-column experiment. The experiment requires suitable adjustment of both experimental conditions and relative dimensions of each of the columns. In this case, a longer column than normally employed in GC x GC allows sufficient retention duration on the second column, which permits the typical plateau-shape recognised for the interconversion process to be observed. The extent of interconversion depends on prevailing temperature, retention time, and the phase type. Polyethylene glycol-based phases were found to result in high interconversion kinetics, although terephthalic acid-terminated polyethylene glycol had a lesser extent of interconversion. Much less interconversion was seen for phenyl-methylpolysiloxane and cyclodextrin phases. This suggests that for the oximes, interconversion largely occurs in the stationary phase. Examples of different extents of interconversion in both dimensions are shown, including peak coalescence on the first column with little interconversion on the second column.

Chromatography, Gas↗

PubMed2004

An alternative approach for the estimation of equivalent temperature in gas chromatography.

The temperature at which the isothermal retention time (tRiso) is equal to the temperature-programmed retention time (tRTPGC) or the isothermal retention index (Iiso) is equal to the temperature-programmed retention index (ITPGC) is defined as the equivalent temperature (Teq). The Teq of one-, two-, three-, and four-step temperature-programmed gas chromatography (TPGC) of unsaturated fatty acid methyl esters (FAMEs) from Chinese mustard seed oil is calculated. All of the tR values obtained at the Teq (tRTeq) are very close to the tRTPGC. The highest difference for each chromatogram is less than 0.5%. The slight deviation may partly arrive from the difficulty in setting the desired carrier gas flow rate. Also, good agreement among equivalent chain length values determined by different methods is observed, including the graphical method at the Teq. Therefore, it is speculated that the proposed method may facilitate the GC identification of FAMEs as well as other organic compounds in TPGC by using the available isothermal retention index database.

Chromatography, Gas↗