Leslie S. Ettre

Determination of gas-liquid partition coefficients by automatic equilibrium headspace-gas chromatography utilizing the phase ratio variation method

SummaryThe new phase ratio variation method is described which represents a convenient way for the determination of gas-liquid partition coefficients for practical purposes, utilizing equilibrium headspace-gas chromatography (EHS-GC). This method is based on the relationship between reciprocal peak area and the phase ratio in the vial containing the sample solution; it involves regression analysis of the EHS-GC measurements of a number of sample vials containing the same sample solution but with a wide variation of phase ratios. Examples are given for both aqueous systems and systems consisting of a stationary (liquid) phase used as the solvent; comparison of the measured values with results obtained by other methods shows satisfactory agreement. A critical discussion of the conditions influencing the accuracy of the analytical results is given.

Theory and practice of multiple headspace extraction

SummaryMultiple headspace extraction (MHE) is an absolute quantitative method used in static headspace—GC. In principle it is dynamic gas extraction, carried out stepwise and establishing equilibrium conditions in each step. The concentration of the analyte in the headspace decreases exponentially during the series of extraction steps: by proper mathematical extrapolation the total peak area proportional to the total amount of analyte present in the original sample can be obtained.This paper investigates MHE from the theoretical point of view using two approaches: a simplified theory regarding MHE as a first-order reaction, and a rigorous, step-by-step treatment of the MHE procedure. Special consideration is given to the fact that the headspace gas is only partially removed between individual steps. As shown, the results of both treatments are essentially the same hence the method is theoretically sound.The practical limitations of MHE are also discussed pointing out how the analytical parameters may be adjusted to improve the possibility of determination by MHE.

Headspace-gas chromatography: The influence of sample volume on analytical results

SummaryThe role of the volume of the sample and the sample vial in equilibrium headspace-gas chromatography is discussed. A new term, thesample phase fraction (ΦS) is introduced. It is shown that if the value of ΦS is kept constant, the vials volume has no influence on the “sensitivity” of the headspace analysis (which is proportional to the concentration of the analyte in the headspace). In a given headspace sampling system, concentration of the compound of interest in the headspace (cG*) at equilibrium is related to the value of ΦS: a higher ΦS will increase cG*. However, the influence is important only in the case of low distribution coefficients: in the case of higher distribution coefficients this influence is negligible. This conclusion is also true for small changes in the sample volume in duplicate analyses: exact reproducibility of the sample volume is important only in the case of low distribution coefficient values.

M. S. Tswett and the discovery of chromatography I: Early work (1899–1903)

SummaryOn the occasion of the 90th anniversary of the Warsaw lecture of M. S. Tswett representing the first report on the chromatographic technique, this two-part article outlines the evolution of the method. This part deals with Tswetts early work in 1899–1901 and his research in 1901–1903 leading to the lecture at Warsaw. The second part will deal with the fundamental twin papers of 1906, with his book of 1910, summarizing all his activities related to the investigation of plant pigments and to the development of chromatography, and with a few special questions related to Tswetts scientific activities in this field.

M.S. Tswett and the discovery of chromatography. II: Completion of the development of chromatography (1903-1910)

SummaryIn this, the second part of our review we continue the discussion of the activities of M. S. Tswett related to the development of chromatography. We shall deal here with his activities in Warsaw from 1903 onwards, resulting in his fundamental twin papers of 1906 and his book of 1910, summarizing all his activities related to the investigation of plant pigments and to the development of chromatography. Finally, a few special questions related to Tswetts work shall be discussed.

New, unified nomenclature for chromatography

SummaryThe most important definitions, terms and symbols included in the new, unified Nomenclature for Chromatography issued by the International Union of Pure and Applied Chemistry (IUPAC) are outlined.

Chromatography: The separation technique of the 20th century

SummaryM. S. Tswett contemplated the possibility of “chromatography” in 1899–1901 while carrying out his first research work on the physico-chemical structure of plant chlorophylls, and he reported “on a new category of adsorption analysis” in 1903. The evolution of chromatography followed the advances of this century: each decade brought new innovations based logically from the previous one. By the end of the 20th Century chromatography has became the most widely used separation technique in chemistry and biochemistry: thus, it is no exaggeration to call it the separation technique of the 20th Century. This paper investigates the evolution of the various branches of chromatography.

The physical meaning of the corrected retention volume

SummaryThe true meanings of the so-called corrected retention volume and the specific retention volume are explained in the light of the recent paper by Davankov.

Early evolution of chromatography: the activities of Charles Dhéré☆

Abstract Charles Dhere (1876–1955), professor at the University of Fribourg (Switzerland), was the first in Europe to recognize the importance of chromatography. While with his students W. Rogowski and G. Vegezzi he improved the laboratory set-up used for chromatography, he also proved the correctness of Tswetts assumptions on the existence of a multitude of chromophyllic and carotenoidic pigments, demonstrated that chromatography can provide purer substances than any of the then accepted methods and further extended the use of chromatography into animal biochemistry. He also provided the first reliable discussion on the life and activities of Tswett, the inventor of chromatography.

Leory Sheldon Palmer (1887–1944) and the beginnings of chromatography in the United States of America

SummaryLeroy Sheldon Palmer (1887–1944) was the first American who utilized chromatography in the investigation of carotenoids present in animals, specially in milk, butter and selected tissues, and in the food intake of the animals. His work represented most likely the first use of chromatography after Tswetts basic publications in 1906. Palmers 1922-book on carotenoids, also describing the methodology of chromatography, served as the transmission between Tswett, the early users of the technique (Palmer, Dhéré), and the “rebirth” of chromatography in 1931 in Heidelberg.