Liquid purification or separation – With means to add treating material – Chromatography
Patent
1989-01-23
1990-10-02
Therkorn, Ernest G.
Liquid purification or separation
With means to add treating material
Chromatography
210101, 210137, 422 70, B01D 1508
Patent
active
049605160
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The present invention relates to analytical instrumentation and has specific reference to the design of liquid microcolumn chromatographs.
PRIOR ART
Known in the art is a liquid microcolumn chromatograph comprising a microcolumn, a unit for feeding eluent in the form of a reservoir separated by a "slack" diaphragm into two chambers of which one communicates with a source of pressure and is filled with a working agent and the other chamber communicates with a source of eluent and with an inlet into the microcolumn, a flow-through cell of a detector located at the outlet of the microcolumn, and an eluent receiver (SU, A, 715996).
In microcolumn chromatography columns with sorbent are used, the particle size of the sorbent being on the order of units of microns. The pressure gradient in such columns reaches hundreds of atmospheres. A high pressure gradient in the microcolumn makes the etuent flow through the heterogenous packing of the column non-uniform. High pressure surges set up when the components of the sample are passing through the sorbent of the microcolumn fail to coincide with the time of passage of these components through the detector cell. Consequently, the detector (which is commonly a high-sensitive one of the refractometer type) records blurred boundaries of chromatographic peaks, corresponding to each component, i.e. the shape of the peaks fails to represent the actual composition of the sample. Moreover, bubbles of the solute gas liberated from the eluent due to the sharp drop in pressure brought about by the descent of the eluent down the chromotographic microcolumn on the one hand, block sorbent channels and, on the other hand, are recorded pores by the detector and interfere with the useful signal. As a result, the accuracy of chromatographic analysis is impaired.
To eliminate the above-stated disadvantages in liquid chromatographs, it is known to employ a means of setting up a backpressure at the outlet of the chromatographic column. Thus, a liquid chromatograph is known, wherein the backpressure at the column outlet is provided in the form of a liquid column (JP, B, 54-19194).
However, the known means of providing backpressure cannot be used in conjunction with liquid microcolumn chromatographs which require that the outlet pressure in the microcolumn should be of the same order as the inlet one-commonly of a significant value as already mentioned above. Only on condition that this requirement is met the pressure fluctuations in the microcolumn can amount to fractions of percent of the pressure in the cell of the detector. To make a liquid column capable of ensuring a requisite outlet pressure in a microcolumn is not feasible.
DISCLOSURE OF THE INVENTION
It is an object of the invention to provide a liquid microcolumn chromatograph which would be equipped with a means for setting up a backpressure at the outlet of the microcolumn thereof, featuring a simple and reliable design, which would enable the elimination of evolution of gas bubbles at the microcolumn outlet, as well as fluctuations of pressure in the microcolumn and, in the final run, enable an increase in the confidence and accuracy of chromatographic analysis.
The essence of the invention consists in that a liquid microcolumn chromatograph comprising a microcolumn, a unit for feeding eluent designed as a main reservoir separated by a "slack" diaphragm into two half-chambers of which one communicates with a main source of pressure and is filled with a working agent and the other half chamber communicates with a source of eluent and with an inlet to the microcolumn, a flow through cell of a detector at the microcolumn outlet, and an eluent receiver, according to the invention, is provided with an additional reservoir separated by a "slack" diaphragm into two half-chambers and given a volume which is essentially greater than the volume of the eluent needed for one analysis and is also provided with an additional source of pressure, one half-chamber of the additional reservoir communicating with an outlet
REFERENCES:
patent: 4165284 (1979-08-01), Guillemin et al.
patent: 4234427 (1980-11-01), Boehme
Alexandrov Maxim L.
Belenky Boris G.
Gotlib Vladimir A.
Komarov Nikolai N.
Shevkunov Vsevolod V.
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