1,720,977 research outputs found
Theoretical calculation of gas hold-up time in capillary gas chromatography. Influence of column, instrument parameters and analysis conditions. Comparison of differet methods of dead times determination
No full textA calculation method for the prediction of effective plate height in capillary gas chromatography.
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Prediction of the plate height of capillary columns operated at any inlet pressure of the carrier gas by using few retention data measured under isobaric conditions.
No full textComparison of different methods for the prediction of retention time in programmed temperature GC
No full textClassification and comparison of capillary columns by determination of the solution enthalpy of polar and non polar probes
No full textThe behaviour and separation characteristics of capillary columns containing different stationary phases (bonded methyl- and methylphenylsiloxanes and polyglycols, and carbon layer and porous polymer) were classified and compared by measuring the values of the solution enthalpy ΔHs of n-alkanes and 1-alcohols at various temperatures. The difference in ΔHs values between straight-chain 1-alcohols and n-alkanes with the same number of carbon atom (ΔΔHs) does not change with changing temperature when gas–liquid partition stationary phases are used, but depends on the column composition and polarity and therefore permits to evaluate the influence of polarity on the solute–solvent interaction. The trend of the ΔΔHs values is correlated with that of the ΔC parameter and with the McReynolds’ polarity constants
Fast and accurat method for the automatic prediction of programmed temperature retention times
No full textRetention models for programmed gas chromatography
No full textThe models proposed by many authors for the prediction of retention times and temperatures, peak widths, retention indices and separation numbers in programmed temperature and pressure gas chromatography by starting from preliminary measurements of the retention in isothermal and isobaric conditions are reviewed. Several articles showing the correlation between retention data and thermodynamic parameters and the determination of the optimum programming rate are reported. The columns of different polarity used for the experimental measurement and the main equations, mathematical models and calculation procedures are listed. An empirical approach was used in the early models, followed by the application of thermodynamic considerations, iterative calculation procedures and statistical methods, based on increased computing power now available. Multiple column arrangements, simultaneous temperature and pressure programming, applications of two-dimensional and fast chromatography are summarised
Automatic prediction of retention times in multi-linear programmed temperature analysis.
No full textStructure-retention correlations of chlorobenzenes as a method for the comparison of the behaviour of gas-liquid-solid and gas-liquid capillary columns of various polarities
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