[On some demographic characteristics of the members of the Russian Academy of Sciences in the 20th century].

The demographic life characteristics of the Russian science elite (full and corresponding members of the Academy of Sciences in 20th century) and the relationship between their birth and death dates are given in the paper. The following demographic characteristics of the RAS members have been estimated: a) the mean life span of full RAS members is 75 years, and of corresponding members--72.1 years; b) the mean life span of full RAS members after their election is 16.6 years, and that of corresponding members is 17 years; c) the mean age of the election to the Academy is 58.4 years for full members and 55 years for the corresponding members. These characteristics were used to analyze the social status of the group representing potential academic elite and to evaluate changes in that status caused by the fact of their election to the Academy. It has been found that the mean, maximum and minimum ages of their election to the Academy actually coincide with respective characteristics of Nobel Prize winners. However the life span of the latter after awarding is significantly, over 3 years, greater than that of full RAS members after their election. There is a small proportion of women among the members of the Academy (2%). This is also true for Nobel Prize winners (3.2%). It is shown that a week period of +/-3 days of the birth date for the members of the Academy is characterized by a much higher mortality rate exceeding the average one by about 60%. A similar tendency was shown earlier for the eminent persons of the world community in literature, science, business, and politics in 18th-20th centuries.

Use of low volatility mobile phases in electroosmotic thin-layer chromatography.

A variant of electroosmotic thin-layer chromatography is suggested with the use of low volatility compounds as mobile phases aimed at drastically decreasing the evaporation of the mobile phase and improving the reproducibility of the method. The linear movement velocity of zones of separated compounds is experimentally shown to increase 2-12-fold in electroosmotic chromatography (compared to similar values in traditional TLC). The separation efficiency is also considerably increased.

Investigations of a new field in gas chromatography: capillary columns with a super-thick layer of stationary liquid phase.

Basic characteristics (efficiency, selectivity, non-equilibrium) of capillary columns with a super-thick layer of stationary liquid phase are investigated. In contrast to traditionally used capillary columns with standard stationary phase thickness of 0.1-0.5 um, some new variables are now established. Firstly, the values of relative retention depend on carrier gas linear velocity. Secondly, the asymmetry of chromatographic peaks increased in accordance with the increase in carrier gas velocity. Thirdly, it was theoretically and experimentally shown that dependence of the height equivalent to a theoretical plate (HETP) on carrier gas velocity is linear. The above noted variables are evidences that the new type of GC is realized under these conditions. The use of capillary columns with super-thick layer of stationary liquid phase is practical when the following problems have to be solved: (1) Separation of highly volatile substances; (2) Preliminary concentration of trace compounds from strong diluted samples; (3) Improvements in measurement and accuracy due to the advantages of splitless injection into wide bore columns with super-thick films. Solutions to some analytical tasks while using super-thick stationary liquid phase are shown: (1) Large volume injection into capillary column with sample transfer speed up to 100 microL min(-1); (2) Isothermal splitless injection; (3) Separation of low boiling compounds; (4) Separation of polar substances (alcohols).

Changes in the basic experimental parameters of capillary gas chromatography in the 20th century.

Studies of qualitative changes in capillary gas chromatography are of significant practical and scientific interest. This paper analyzes the evolution of the most important experimental chromatographic parameters over the last three decades and is based on the use of a new approach to scientometrical research that is referred to as applied scientometry. One essential feature of this approach is that it looks at the entire contents of each paper rather than only taking account its title, abstract. and references (as is typical for conventional scientometry). In this paper, we monitor how the most important chromatographic parameters, such as column length and diameter, layer thickness, stationary liquid phases, separation temperature mode. etc., have been evolving over the period 1970-2000. We used data from the following journals: Chromatographia, Journal of Chromatography, and Journal of High Resolution Chromatography and Chromatography Communications.

Carrier gas as a new factor influencing the selectivity of the gas-stationary liquid phase chromatographic system.

This paper generalizes studies on the influence of carrier gas on relative and absolute retention values. This line of research is also of importance due to the fact that, in the opinion of many chromatographers, the role of the carrier gas is limited only to transporting analyzed compounds along the column. However, even under conditions of the conventional capillary gas-liquid chromatography (i.e. at column pressures under 5 atm) carrier gas (its nature and pressure) significantly influences retention and separation of the analyzed compounds. First, carrier gas (N2 and CO2, for example) dramatically affects relative retention values. For this reason, one should use limit values of alpha(ij) (0) = lim alpha(ij)(P(av)) and I(i)(0) = lim Ii(Pav) I(0) = limI(i) (Pav) with Pav-->0 as chromatographic constants, rather than traditional relative retention values alpha(ij)(P(av)) and I(i)(P(av)). Second, the average pressure Pav of the carrier gas in a column and the nature of the carrier gas influence the selectivity of the gas-stationary liquid phase chromatographic system. Third, wishing to maximize the role of the carrier gas as a factor that improves separation of analyzed compounds, we should design a special gas chromatograph that would allow work with pressures in the column up to 30-50 atm.

Needle-type concentrator and its application to the determination of pollutants.

A new method for impurity concentration in gas and liquid media using a needle type microconcentrator was developed. The main advantage of this method using microconcentrators is its efficiency and simplicity. Our work was stimulated by Pawliszyn's solid-phase microconcentration method.

Effect of efficiency improvement by injecting a sample at a lower carrier gas velocity in isothermal gas-liquid chromatography.

The effect of efficiency improvement of chromatographic system by injecting a sample at a lower carrier gas velocity (in comparison with the carrier gas velocity at subsequent separation) was studied experimentally and theoretically in isothermal gas-liquid chromatography. The suggested technique is based on sample introduction in the programmed carrier gas velocity operation mode: the injection is realized at low carrier gas velocity, then the velocity is increased rapidly up to the operation value. The technique can be applied in chromatographic practice.

Ammonia as carrier gas in capillary gas-liquid chromatography.

Influence of helium and ammonia as carrier gases on retention of neutral solutes on polyethylene glycol has been studied theoretically and experimentally. It was shown that the influence of ammonia on the retention varied significantly depending on the solute's nature. For example, the influence is great for C22 n-alkane and it is small for phenol. Taking into account the results obtained by various researchers it makes sense to express an opinion on the expediency of development of gas chromatography operated under the conditions of acidic-basic chromatography.

Use of equations for the description of experimental dependence of the height equivalent to a theoretical plate on carrier gas velocity in capillary gas-liquid chromatography.

Optimal equation for fitting the experimental data on the height equivalent to a theoretical plate (HETP) versus carrier gas velocity in GLC was determined. The data obtained by authors and the literary data by other investigators were used for the comparative study of Van Deemter, Golay and the little known Golay-Guiochon equations. The Golay-Guiochon equation takes into account instrumental contribution and other sources of additional band broadening. Correlation coefficient R and Pirson's criterion chi2 were used as a criterion of the data correspondence to the equations. The Golay-Guiochon equation is the best for fitting of the experimental data in 71% considered examples, 19% experimental data may be fitted very precisely by the Van Deemter equation, the Golay equation is preferable for 7% experimental data only. Three percent experimental data may be fitted with the same precision by the Golay and the Van Deemter equations. The results obtained are of theoretical and practical interest. The Golay-Guiochon equation must be used more widely in analytical practice and physicochemical measurements.

Ammonia as a carrier gas for acidic-basic chromatography.

The influence of ammonia as a basic carrier gas on the retention of acidic and basic solutes was experimentally studied. Use of the basic carrier gas (ammonia) leads to an increase in retention of acidic solutes. A simplified theory on the influence of carrier gas basicity influence on the retention of acidic and basic solutes was developed. Contact of an inert gas with ammonia water at ambient temperature can be used to obtain basic humid carrier gas and to improve the chromatographic characteristics of amine's zones.

Thin-layer chromatography with mobile phases of low volatility.

The analytical possibilities and specific features of a variation of thin-layer chromatography with mobile phases of low volatility (which may be organic liquids or melts of organic solids) are discussed.