Observations on response factors for thermal conductivity detectors in GLC analysis of fatty acid methyl esters

Abstract

Various erratum factors have been proposed for quantitative analysis of fatty acid methyl ester mixtures by isothermal gas‐liquid chromatography (GLC) employing thermal conductivity detectors in an effort to obtain more accurate values. These factors include multiplication of the area of each peak by the square root of the molecular weight of each component before calculating the percentage of each compound in the mixture or applying erratums for relative molar response for saturated esters and relative mass response for unsaturated esters. These proposed factors are not valid erratums for detector response but fortuitously are approximate compensations for lack of optimum operating conditions for each component. This is shown from the analysis of a number of standard fatty acid methyl ester mixtures by isothermal and programmed temperature GLC where the detector is maintained under identical conditions. Isothermal GLC requires different factors each time operating conditions are altered appreciably while proper temperature programming required little or no erratums depending on the particular mixture of methyl esters.

Advances in Computational Fluid Dynamics (CFD) Modeling of In-Cylinder Biodiesel Combustion

“…For the estimation of the liquid thermal conductivity of biodiesel fuels, the Robbins Kingrea method, which is a function of the critical temperature, liquid heat capacity, liquid density, and latent heat of vaporization at the normal boiling point, was utilized by Mohamed Ismail et al Separately, Baroncini’s method was used in the work reported by Golovitchev and Yang . Meanwhile, Ra et al used similar experimental methods and group contributions methods − to estimate the liquid thermal conductivity of soybean biodiesel. The DIPPR software has also been used successfully for this purpose …”

“…Thus, this method was used to predict the vapor heat capacity required for the subsequent calculations of vapor viscosity and vapor thermal conductivity . Many different approaches − were also used by Ra et al and Chakravarthy et al in order to ensure accurate estimation of the vapor heat capacity of soybean biodiesel.…”

Coatings

“…In calibration studies of gas chromatographic systems for the quantitative analysis of fatty acid methyl esters, Sheppard, Meeks, and Elliott (110) concluded that individual fatty acids require correction factors for both weight and molar determinations. From observations made on response factors for thermal conductivity detectors, Herb, Magidman, and Riemenschneider (53) concluded that the various proposed correction factors for fatty acid methyl VOL. 41, NO.…”

Gas chromatography

“…Dietz (182) measured the response factors of a variety of compounds for both the flame ionization detector and the thermal conductivity detector. Other workers (248) suggest that measurement of response factors for a thermal conductivity detector should be performed during temperature programming of the column to reduce differences in response factors observed under different isothermal conditions. Relative molar response factors for C8 to C24 fatty acid methyl esters were reported using the flame ionization detector (649) and for Ci to Ce amines, cyclic amines, and hydrocarbons using a thermal conductivity detector (616).…”