Liquid purification or separation – Processes – Chromatography
Reexamination Certificate
1999-12-27
2001-08-28
Smith, Duane (Department: 1724)
Liquid purification or separation
Processes
Chromatography
C210S659000, C073S061520, C073S061560
Reexamination Certificate
active
06280627
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a liquid chromatograph with a fraction collector and more particularly to such a liquid chromatograph using a mass analyzer as the fraction collector.
As a technology related to liquid chromatography, it has been known to provide a fraction collector on the downstream side of the flow route so as to selectively collect only a target component contained in a sample. Normally, the part of a liquid chromatograph serving to collect a fraction (herein referred to as the “fraction collecting device”) includes a liquid pump, a sample injector, a column, a detector, a fraction collector and a system controller for controlling the collection of the fraction. When the detector detects the peak of the target component, the device functions so as to activate a switch valve when the component corresponding to this peak arrives at the switch valve of the fraction collector for its collection. An ultraviolet visible light detector is usually used as the detector for monitoring the sample solution flowing through a flow cell provided on the downstream side of the column.
Recently, a mass analyzer is coming to be used instead of an ultraviolet visible light detector for collecting a fraction with high accuracy. A prior art fraction collecting device for a liquid chromatograph using a mass analyzer as its detector is shown in
FIG. 1
wherein numeral
1
indicates a liquid pump, numeral
2
indicates a sample injector, numeral
3
indicates a column for separating components, numeral
4
indicates a splitter, numeral
5
indicates a system controller, numeral
6
indicates a mass analyzer serving as a detector, numeral
7
indicates a fraction collector, numeral
8
indicates a flow route for carrying out the analysis, numeral
9
indicates a fraction collector flow route, and numeral
10
indicates a control unit comprising a personal computer. A fraction collecting device using a mass analyzer as its detector is characterized as being provided with a splitter
4
for branching the flow route into the route for analysis
8
connected to the mass analyzer and the fraction collector flow route
9
connected to the fraction collector. The flow rate of the mobile phase is normally maintained at about several tens of ml/min when the collection of a fraction is carried out, but since the maximum flow rate to the mass analyzer is only 2 ml/min, only a small portion of the sample solution eluted from the column
3
is arranged to be branched into the mass analyzer
6
. Since the mass analyzer
6
analyzes a sample solution by ionizing it and its collection becomes difficult after the analysis, only a portion of the sample solution is used for the analysis and the rest is directed for collection.
Thus, a fraction collecting device for a liquid chromatograph is provided with a splitter on the downstream side of the column but the conditions for the collection of fraction such as the flow rate of the mobile phase must be varied, depending on the kind of the sample to be fractioned. In addition, the mode of ionization such as the electro-spray method and the atmospheric chemical ionization method must also be modified. Thus, the split ratio by means of the splitter must also be adjusted such that an optimum condition can be obtained.
It has been known to exchange the fraction collector flow route from the splitter to the fraction collector in order to change the split ratio until a desired split ratio is obtained according to the sample. It is cumbersome, however, to actually exchange the flow route. The manners in which the screws are tightened may even cause deformations of the pipes and a change in the dead volume.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a fraction collector with an improved capability by eliminating such cumbersome processes and reducing the dead volume.
A fraction collecting device for a liquid chromatograph embodying this invention, with which the above and other objects can be accomplished, may be characterized not only as having a splitter for branching the flow from the column into two flow routes individually connected to a mass analyzer and a fraction collector but wherein a plurality of pipes each having a different flow resistance and connected in parallel with respect to one another are inserted into either of these two flow routes and valves are connected such that one of these parallel-connected pipes can be selectively connected to the column through the splitter. A control unit serves to select one of these plurality of pipes and to cause the valves to connect the selected pipe to the column.
REFERENCES:
patent: 5135718 (1992-08-01), Kawaguchi et al.
patent: 5240577 (1993-08-01), Jorgenson et al.
patent: 5338514 (1994-08-01), Morabito et al.
patent: 5462660 (1995-10-01), Singleton et al.
patent: 6077438 (2000-07-01), Zambias et al.
patent: 4130028 (1992-04-01), None
patent: 96/ 40398 (1996-12-01), None
Coudert Brothers
Hoey Betsey Morrison
Shimadzu Corporation
Smith Duane
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