Yu. I. Arutyunov

Averaging the pressure and flow rate of the carrier gas in a gas chromatographic column

SummaryA systematic derivation of corresponding equations shows that averaging the pressure and the flow rate of the mobile phase in a gas chromatographic column over the column length and over the time that an unretained component resides in the column, requires the use of three different compressibility correction factors,j21,j32, andj43. When multiplied by the adjusted retention volume,VR-VM, the Martin and James mobile phase compressibility correction factorj32, only, produces the value of specific retention volume,VgT, which is connected unambiguously with the thermodynamic phase distribution coefficient,K, of the sorbate.

Subcritical water extraction of biologically active substances from milk thistle seed (Silybum murianum L.)

A method of subcritical water extraction (SCWE) of biologically active substances from milk thistle seed (Silybum marianum L.) that makes it possible to obtain aqueous extracts without using organic solvents is suggested. The contents of hepatoprotective biologically active substances (taxifolin, silychristin, silydianin, and silybin) in milk thistle seed extracts obtained by SCWE and by standardized liquid extraction procedures are compared.

Influence of flow parameters of the mobile phase on the retention and thermodynamic characteristics of sorption in gas-liquid chromatography

The influence of the flow parameters of the mobile phase (flow rate and mean pressure in the column) on the retention and thermodynamic characteristics of sorption in gas-liquid chromatography is studied experimentally. Conditions are formulated under which the chromatographic process can be described in terms of the theory of equilibrium gas-liquid chromatography with an ideal gas as the mobile phase and the distribution of the sorbate between phases is not affected by the presence of a weakly sorbed carrier gas.

New methods for determining the volumetric flow rate in the column and the retention time of the unretained substance in gas chromatography

New methods for calculating the mean volumetric flow rate of the carrier gas and the retention time of the unretained substance in the column under conditions of gas chromatography were proposed. The methods are based on preliminary isothermal calibrations of the flow rate and holdup time for a packed column. A theoretical substantiation of the methods was given. Procedures of plotting calibration dependences for determining the indicated quantities at a desired temperature were described. The calculation results were compared to experimental data obtained by traditional methods. It was demonstrated that the use of calculation methods substantially simplifies the determination of the specific retention volume over a wide temperature range.

Gas chromatography parameters of volatile compounds in growths and pharmaceuticals of Milk Thistle (Silybum marianum L.)

AbstractsBased on a gas chromatography investigation of volatile compounds in growths and pharmaceuticals of Milk Thistle (Silybum marianum L.), chances for the assessment of the identity of raw materials and fitodrug were established by the account of a set of retention indexes of these compounds on a standard capillary column with a polydimethylsiloxane stationary phase.

Planar microchromatographic columns for gas chromatography

The adsorption and selective properties of aluminum-based planar microcolumns filled with the Carbopack B adsorbent are studied. The effect of geometrical parameters of the columns on their chromatographic properties is considered on an example of the separation of a mixture of light hydrocarbons. The advantages of planar microcolumns compared to conventional packed chromatographic columns are revealed.