Abstract. It is shown that an interference-polarizing refractometric detector makes it possible to use microcolumn size-exclusion chromatography (MSEC) columns with inner diameters of 0.2 to 0.5 mm and ensures a detection limit (at a signal to noise ratio of 3) of 8 x Taking into account the above requirements, a micro-gel chromatograph with a refractometric (interference-polarizing) detector was developed. Teflon columns gave reproducibilities (the mean square deviation at the 95% confidence level) of retention times and signal amplitudes of 0.2 % and 0.5 %, respectively, which ensures reproducibilities of molecular weight determinations within about 2 to 4 % . Examples of polymer and protein analyses carried out on this chromatograph are given. It is suggested that a micro-gel chromatograph can be developed for fused-silica capillary columns with inner diameters of 0.2 mm. This would permit analysis of approximately 10 pg of polymer. refractive index units.

Abstract. The problems of microcolumn size-exclusion chromatography and its instrumentation are considered. It is shown that the reproducibility of retention times of a micro-gel chromatograph depends on the stability of eluent delivery by a syringe micropump. It is possible to increase this stability and to suppress the relaxation processes related to the changes in hydrodynamic column resistance and in the solvent temperature in the pump chamber.In order to suppress instability when columns of 0.5-mm inner diameters are used, the volume of the eluent delivery system should be as small as possible (Vp < 1 mL) and the system should be thermostatted at AT (P,(a/fl)6 where P, is the pressure under conditions of constant pump pressure, a and fl are the coefficients of thermal expansion and compressibility of the liquid, and 6 is the permissible retention time error (At&).

Micro column exclusion chromatography (MEC) Laser refractometric detector (LR-1)Exclusion chromatography on microcolumns 0.5-1 mm in diameter is an efficient and very economical method of investigating molecular-weight distribution (MWD) of polymers. In fact, the application of columns of 0.5 -1 mm instead of 4 mm in diameter makes it possible to reduce the consumption of sorbent and eluent by a factor of 25-100 thus permitting the use of any solvents, even very expensive ones, under rigorous conditions of toxic and fire safety.

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