Role of background detector response in quantitative gas chromatography

Abstract

A theoretical analysis of the effects of the background detector response on the net response to a substance was performed. The effects were investigated experimentally with the use of two stationary phases of different volatilities, employing the flame ionization detector. The change in relative response factors caused by bleeding of the stationary phase and the systematic errors incidental to the use of a volatile stationary phase in quantitative PTGC are demonstrated, ANY GAS CHROMATOGRAPHIC DETECTOR, operated under usual conditions in a conventional set-up, produces a certain background response. Despite attempts to compensate for this response, it usually enhances the noise level and should therefore be kept as low as possible. There are some exceptional cases in which the response to the presence of the component eluted (net response) is given by a decrease in the background response [e.g. the electron capture detector ( I ) ] or in which the positive response is proportional to the background response (2, 3) [e.g., the alkali flame ionization detector (4, 5)]. These special cases obviously require a compromise in the setting of the detector sensitivity to attain optimum performance.There is still another problem associated with the background detector response. AS shown below, in spite of various methods of compensating for the background response, it may cause a decrease in the net response. In this

Gas chromatography

“…Barry and Rosie (56,59) reported that the relative molar response factors for the thermal conductivity detector may be accurately predicted from thermal conductivity coefficients and other physical properties of the chromatographic fraction and the carrier gas. A decrease in the net signal response owing to the background signal in the flame ionization detector from liquid phase bleed was reported by Novak et al (648).…”

“…Grant and Clarke (319) investigated the quantitative effects of the chromatographic and detector conditions on the analytical precision of the FID and found that the use of a carefully chosen internal standard appears to be essential for achieving high precision. Novak et al (648) showed that the background detector signal (carrier gas plus stationary phase vapor) causes a decrease in the net response of the detector, even when it is operated in the linear range. That the sample size can be increased by at least two orders of magnitude beyond the limit of the linear range of the FID has been shown by Rossiter (730), as the logarithm of the sample size and the peak area are linearly related.…”

Gas chromatography

“…A continuous, steady state flow system was developed for dynamic detector calibration. A theoretical analysis of the effects of the background detector response on the quantitative performance of detectors treated the change in relative response factors caused by column bleed and the systematic errors incidental to the use of a volatile stationary phase in program temperature GC (700).…”

“…This method has found application in trapping organic vapors from the atmosphere (46), quantitative analysis of fragrant components by collection on an adsorption microcolumn (446), analysis by GC or mass spectrometry (597), and as a means of eliminating solvent peaks (229). Methods of sampling from closed, pressurized systems (704), and vacuum systems have been found to be of importance in studying gas phase reactions (365).…”