Peak Capacity Calculation in Capillary Gas Liquid Chromatography

1995 ◽  
Vol 60 (4) ◽  
pp. 559-567 ◽  
Author(s):  
Ján Krupčík ◽  
Tibor Hevesi ◽  
Pat Sandra
Keyword(s):  
Retention Time ◽  
Variable Parameter ◽  
Peak Capacity ◽  
Gas Liquid Chromatography ◽  
Peak Width ◽  
Linear Temperature ◽  
Cubic Equation ◽  
Capacity Calculation ◽  
Temperature Rate ◽  
Temperature Programmed

A method is suggested for the determination of the peak capacity in isothermal and temperature-programmed high resolution gas chromatography (HRGC). The calculation is based on the integral by Grushka and Giddings, requiring that the dependence of the peak width on the retention time be known. Regression analysis of experimental data gave evidence that in isothermal and linear temperature-programmed HRGC where the temperature rate is the single variable parameter, the dependence of the peak width on retention time can be approximated by a linear equation. Substitution of this linear dependence in the integrand gives an integral which can be solved analytically. For temperature-programmed HRGC with two variable parameters, viz. the time of initial isothermal period and the temperature rate, the above dependence can be fitted with a cubic equation. The resulting integral is more complex and has to be solved numerically. The peak capacities calculated by the procedure suggested and by the use of the separation number (TZ) are in a good agreement.

Rapid Extraction and Gas-Liquid Chromatographic Determination of Benzoic and Sorbic Acids in Beverages

1983 ◽  
Vol 66 (1) ◽  
pp. 209-211
Author(s):  
Ricardo G Coelho ◽  
David L Nelson
Keyword(s):  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
Benzoic Acids ◽  
Ethereal Extract ◽  
Rapid Extraction ◽  
Liquid Chromatographic Determination ◽  
Carbonated Drinks ◽  
Temperature Programmed ◽  
Liquid Chromatographic

Abstract A rapid method for extraction and quantitative determination of sorbic and benzoic acids in carbonated drinks and fruit juices is described. Acidified sample aliquots are transferred onto an Extrelut column. Acid preservatives are then eluted from the column with a mixture of ethyl ether-petroleum ether. Content of preservatives in the concentrated ethereal extract is readily determined by temperature-programmed gas-liquid chromatography without the need to prepare derivatives.

scholarly journals Bonding States of Hydrogen in Plasma-Deposited Hydrocarbon Films

2020 ◽  
Vol 6 (1) ◽  
pp. 3 ◽  
Author(s):  
Wolfgang Jacob ◽  
Thomas Dürbeck ◽  
Thomas Schwarz-Selinger ◽  
Udo von Toussaint
Keyword(s):  
Hydrogen Content ◽  
Release Kinetics ◽  
Binding Energies ◽  
Hydrogen Release ◽  
Linear Temperature ◽  
Exponential Factor ◽  
Temperature Ramp ◽  
Temperature Ramps ◽  
Diffusive Effects ◽  
Temperature Programmed

We applied temperature-programmed desorption (TPD) spectroscopy to study the bonding of hydrogen in amorphous hydrogenated carbon (a–C:H) films. Typical hard plasma-deposited a–C:H films with an initial hydrogen content (H/(H+C)) of about 30% were used as samples. About 85% of the initial hydrogen content is released in the form of H2, the rest in the form of hydrocarbons. Using a temperature ramp of 15 K/min, release of hydrogen starts at about 600 K with a first peak at about 875 K and a broad shoulder around 1050 K. The peak positions depend on the temperature ramp. This fact was exploited to determine the pre-exponential factor for an analytic analysis of the release spectra. This analysis revealed a pre-exponential factor of ν = 1 × 10 16 1/s, which deviates significantly from the frequently assumed prefactor 1 × 10 13 1/s. This higher prefactor leads to a shift in the determined binding energies by about +0.5 eV. Standard TPD measurements with linear temperature ramps up to 1275 K were complemented by so-called “ramp and hold” experiments with linear ramps up to certain intermediate temperatures and holding the samples for different times at these temperatures. Such experiments provide valuable additional data for investigation of the thermal behavior of the investigated films. Our experiments prove that the width of the hydrogen release spectrum is determined by a distribution of binding energies rather than release kinetics or diffusive effects. This binding energy distribution has a peak at about 3.1 eV and a shoulder at higher energies extending from about 3.6 to 3.9 eV.

scholarly journals Gas-Liquid Chromatography–Mass Spectrometry Characterization of Polychlorinated Biphenyls (Aroclors) and 36Cl-Labeling of Aroclors 1248 and 1254

1971 ◽  
Vol 54 (4) ◽  
pp. 801-807
Author(s):  
David L Stalling ◽  
James N Huckins
Keyword(s):  
Mass Spectrometry ◽  
Aquatic Organisms ◽  
Sample Introduction ◽  
Gas Liquid Chromatography ◽  
Liquid Chromatography Mass Spectrometry ◽  
Radioactive Materials ◽  
Isomer Composition ◽  
Temperature Programmed ◽  
Uptake And Metabolism

Abstract The isomer composition of the Aroclor 1200 series was characterized by GLC-MS, using temperature programming and SE-30 support-coated, open-tubular capillary columns. A method is described for the preparation and purification of 36Cl-labeled Aroclors 1248 and 1254. Neutron irradiation of the commercial material was used to prepare the 36Cl-labeled material. Purification of the irradiated product was accomplished by silicic acid column chromatography. Yields of the purified product were between 63 and 99%, with no detectable alteration of the isomer composition; 10% of the 36C1 produced was associated with the unchanged PCB isomers and the remaining radioactivity was contained in polychlorinated terphenyls. The terphenyls were produced by irradiation polymerization, and they were easily separated from the PCB components. Mass spectrometry, utilizing either temperature programmed GLC or direct probe sample introduction, was used to characterize the irradiation products. The radioactive materials are being utilized in experiments to determine uptake and metabolism of PCB by aquatic organisms.

Sign in / Sign up

Export Citation Format

Share Document