Hydrodynamic injector

Abstract

A hydrodynamic injector for substantially concurrently loading fluid samples to be analyzed into multiple capillary tubes of a capillary electrophoresis system. The injector includes an enclosure defining a pressure chamber for holding multiple receptacles, each containing a fluid sample, and apertures in the enclosure for passing capillary tubes into a position inside the pressure chamber and in fluid communication with the samples in respective receptacles. Electrodes on the enclosure extend into the pressure chamber for reception in the receptacles. The pressure chamber is pressurized with gas to substantially concurrently force the fluid samples from respective receptacles into the capillary tubes in preparation for a capillary electrophoresis operation.

What is claimed is  
     
         1 . A hydrodynamic injector for substantially concurrently loading fluid samples to be analyzed into multiple capillary tubes of a capillary electrophoresis system, said tubes having first and second ends, said injector comprising: 
 an enclosure defining a pressure chamber for holding multiple receptacles, each containing a fluid sample therein,    apertures in the enclosure for passing capillary tubes into a position wherein first ends of the tubes are positioned in said pressure chamber in fluid communication with the samples in respective receptacles,    electrodes on the enclosure extending into the pressure chamber for reception in said receptacles;    said enclosure having a gas inlet for pressurizing the pressure chamber whereby said fluid samples are substantially concurrently forced from respective receptacles into the first ends of respective capillary tubes in preparation for a capillary electrophoresis operation.    
     
     
         2 . An injector as set forth in  claim 1  wherein said enclosure includes a movable part movable between an open position away from the enclosure to permit access to said receptacles and a closed position in sealing relation with the enclosure so that the pressure chamber can be pressurized.  
     
     
         3 . An injector as set forth in  claim 2  wherein said movable part is configured for supporting a tray having said multiple receptacles therein.  
     
     
         4 . An injector as set forth in  claim 3  further compressing a power actuator for moving said moveable part between said open and closed positions.  
     
     
         5 . An injector as set forth in  claim 4  wherein said movable part has a surface with a recess therein sized and shaped to receive said tray and to hold it in a fixed predetermined portion relative to said movable part.  
     
     
         6 . An injector as set forth in  claim 1  further comprising a channel in said enclosure surrounding the pressure chamber and communicating with said gas inlet, and passages connecting the channel and the pressure chamber at spaced intervals around the pressure chamber.  
     
     
         7 . An injector as set forth in  claim 1  further comprising means for fixedly and sealingly securing the capillary tubes in respective apertures in the enclosure.  
     
     
         8 . An injector as set forth in  claim 1  further comprising a gas supply system for supplying pressurized gas to said pressure chamber, said gas supply system comprising a source of pressurized gas, an accumulator having an inlet and an outlet, an accumulator inlet line connecting the source of pressurized gas to the inlet of the accumulator, an accumulator outlet line connecting the accumulator to the gas inlet of the enclosure, and a valve in the accumulator outlet line movable from a closed position to an open position after the accumulator has been pressurized for effecting the transfer of gas under pressure from the accumulator to the pressure chamber of the enclosure.  
     
     
         9 . An injector as set forth in  claim 8  further comprising a pressure controller in said accumulator inlet line for controlling the pressure in said accumulator.  
     
     
         10 . An injector as set forth in  claim 9  wherein said pressure chamber has a first volume and said accumulator has a second volume, the ratio of said first volume to said second volume being in the range of 5:1-1:5.  
     
     
         11 . An injector as set forth in  claim 10  wherein said ratio is in the range of 2:1-1:2.  
     
     
         12 . An injector as set forth in  claim 11  wherein said ratio is about 1:1.  
     
     
         13 . An injector as set forth in  claim 8  wherein said accumulator outlet line and the gas inlet of the enclosure are sized so that pressure equilibrium in said pressure chamber is reached at about one second after said valve is opened.  
     
     
         14 . An injector as set forth in  claim 8  further comprising a vent system for venting the accumulator and said pressure chamber when said valve is open.  
     
     
         15 . An injector system as set forth in  claim 1  wherein said enclosure is a first enclosure and said system further comprises a second enclosure having a second chamber therein containing one or more receptacles for receiving fluid samples transmitted through the capillary tubes from the first enclosure, apertures in the second enclosure for passing said capillary tubes into a position wherein second ends of the tubes are positioned in said second chamber for the flow of fluid into said one or more receptacles, and electrodes on the second enclosure extending into the second chamber for reception in said one or more receptacles.  
     
     
         16 . An injector as set forth in  claim 15  wherein said second pressure chamber is a pressure chamber adapted for holding multiple receptacles, each containing a fluid sample therein, said second enclosure having a gas inlet for pressurizing the pressure chamber whereby said fluid samples in the second enclosure are simultaneously forced from respective receptacles into the second ends of respective capillary tubes in preparation for a capillary electrophoresis operation.  
     
     
         17 . An injector as set forth in  claim 16  in combination with said capillary tubes, said tubes extending between said first and second enclosures and having portions defining a detection window for the passage of light therethrough, said detection window being at a location closer to one enclosure than the other.  
     
     
         18 . A method of capillary electrophoresis involving the substantially concurrent transfer of fluid samples from multiple receptacles into first ends of multiple capillary tubes, said method comprising: 
 positioning the first ends of the capillary tubes and the receptacles in a single pressure chamber so that the first ends are in fluid communication with the samples in the receptacles,    pressurizing the pressure chamber to force fluid from the receptacles into the capillary tubes, and    causing an electric current to flow through the capillary tubes and contents thereof to cause a first capillary electrophoresis operation.    
     
     
         19 . A method as set forth in  claim 18  wherein said pressurizing step comprises pressurizing an accumulator to a predetermined pressure, and then establishing gas flow communication between the accumulator and said pressure chamber to pressurize the pressure chamber.  
     
     
         20 . A method as set forth in  claim 19  wherein said pressurizing step is carried out so that the pressure in said pressure chamber reaches equilibrium in no longer than about one second after said gas flow communication is established.  
     
     
         21 . A method as set forth in  claim 20  further comprising sizing the volumes of the pressure chamber and accumulator so that the ratio of the pressure chamber volume to said accumulator volume is in the range of 5:1-1:5.  
     
     
         22 . A method as set forth in  claim 21  wherein said ratio is in the range of 2:1-1:2.  
     
     
         23 . A method as set forth in  claim 22  wherein said ratio is about 1:1.  
     
     
         24 . A method as set forth in  claim 18  wherein said pressure chamber is a first pressure chamber, said method further comprising positioning second ends of the capillary tubes in a second pressure chamber containing multiple receptacles for receiving said second ends.  
     
     
         25 . A method as set forth in  claim 24  further comprising causing a second electrophoresis operation by pressurizing the second pressure chamber to a pressure greater than the pressure in said first pressure chamber to force fluid from the receptacles in the second pressure chamber into the second ends of the capillary tubes, and causing an electric current to flow through the capillary tubes and contents thereof to cause capillary electrophoresis during which said fluid flows from the second pressure chamber to said first pressure chamber.  
     
     
         26 . A method as set forth in  claim 24  further comprising detecting the flow of said fluid samples as they move through the capillary tubes at a location other than midway between said first and second pressure chambers.