Determination of heats of vaporization and gibbs free energies of alkylbenzenes on GC stationary phases of different polarity

1998 ◽  
Vol 48 (1-2) ◽  
pp. 89-94 ◽  
Author(s):  
K. Héberger ◽  
T. Kowalska
Keyword(s):  
Stationary Phases ◽  
Free Energies ◽  
Heats Of Vaporization

Gas-Liquid Chromatographic Determination of Technical Chlordane Residues in Food Crops: Interpretation of Analytical Data

1975 ◽  
Vol 58 (5) ◽  
pp. 1051-1061
Author(s):  
William P Cochrane ◽  
James F Lawrence ◽  
Young W Lee ◽  
Ronald B Maybury ◽  
Brian P Wilson
Keyword(s):  
Field Experiments ◽  
Stationary Phases ◽  
Analytical Data ◽  
Chromatographic Determination ◽  
Electron Capture Detection ◽  
Food Crops ◽  
Liquid Chromatographic Determination ◽  
Consistent Method ◽  
Liquid Chromatographic

Abstract An interlaboratory investigation of technical chlordane residues in food crops was carried out to determine the most practical and consistent method of reporting results. Using a technical chlordane reference standard, 8 gas chromatographic stationary phases were studied for their resolution capabilities. The best separations were obtained with SE-30 and its OV-1 equivalent. Using these columns and electron capture detection, potatoes and carrots from supervised field experiments were analyzed in duplicate and quantitated by using 4 methods of calculation. The data were statistically treated to determine the precision and bias for each method. Also, 1 sample was analyzed in duplicate on 2 different occasions by 6 laboratories to substantiate the initial conclusions. Based on the criterion of high precision it is suggested that a comparison of total area under the chromatogram of the sample with total area of a standard technical chlordane be the method of quantitation. Only peaks which are common to both standard and sample have any significance in this type of calculation.

scholarly journals Computational Determination of Binding Structures and Free Energies of Phosphodiesterase-2 with Benzo[1,4]diazepin-2-one Derivatives

2010 ◽  
Vol 114 (48) ◽  
pp. 16020-16028 ◽  
Author(s):  
Bo Yang ◽  
Adel Hamza ◽  
Guangju Chen ◽  
Yan Wang ◽  
Chang-Guo Zhan
Keyword(s):  
Free Energies

scholarly journals A Comparative Study of Advanced Stationary Phases for Fast Liquid Chromatography Separation of Synthetic Food Colorants

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3335
Author(s):  
Ivona Lhotská ◽  
Petr Solich ◽  
Dalibor Šatínský
Keyword(s):  
Separation Efficiency ◽  
Water Solution ◽  
Stationary Phases ◽  
Gradient Elution ◽  
Synthetic Food Colorants ◽  
Liquid Chromatography Separation ◽  
Method Optimization ◽  
Superficially Porous Particles ◽  
Fast Liquid Chromatography

Food analysis demands fast methods for routine control and high throughput of samples. Chromatographic separation enables simultaneous determination of numerous compounds in complex matrices, several approaches increasing separation efficiency and speed of analysis were involved. In this work, modern types of column with monolithic rod or superficially porous particles were employed and compared for determination of eight synthetic food dyes, their chromatographic performance was evaluated. During method optimization, cyano stationary phase Chromolith Performance CN 100 × 4.6 mm and Ascentis Express ES-CN 100 × 4.6 mm, 5 µm were selected for the separation of polar colorants. The separation was performed by gradient elution of acetonitrile/methanol and 2% water solution of ammonium acetate at flow rate 2.0 mL min−1. Mobile phase composition and the gradients were optimized in order to enable efficient separation on both columns. The method using fused-core particle column provided higher separation efficiency, narrow peaks of analytes resulted in increased peak capacity and shortening of analysis time. After the validation, the method was applied for analysis of coloured beers, soft drinks and candies.

scholarly journals Quantification of Fructans in Bioethanol Stillage Based On a Simplified Analytical Method

2021 ◽  
Author(s):  
Andreas Zimmermann ◽  
Martin Kaltschmitt
Keyword(s):  
Analytical Method ◽  
Measurement Errors ◽  
Process Development ◽  
Stationary Phases ◽  
New Approach ◽  
Sample Matrix ◽  
Sample Throughput ◽  
Complex Sample ◽  
Potential Substrate

Abstract Bioethanol stillage, the main by-product of industrial bioethanol production, is a potential substrate for fructans. However, the determination and quantification of fructans in such complex sample matrices is still a challenge for the corresponding analytics to be overcome in order to allow for the identification and utilisation of such unused fructan sources. Especially a possible utilisation or rather the corresponding process development requires appropriate analytics first. Thus, this paper aims to illuminate the basics of fructan quantification in stillage and the corresponding challenges particularly arising with widely used HPLC-RID systems. On this basis, a new approach for fructan quantification is presented based on such HPLC-RID systems allowing for a reliable and especially simple fructan determination in bioethanol stillage for comparably high sample throughput. The developed method performs fructan quantification by determination of fructose and glucose equivalents after a targeted acidic hydrolysis adapted to the respective sample matrix. By means of two different stationary phases, the problem of limited resolution in case of HPLC-RID is overcome and thus measurement errors are reduced. The approach towards the adapted analytical method can be transferred easily to comparable complex sample matrices.

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