The Multisampler transport mechanism uses a Cartesian robot. The X-Y drive together with the Z drive optimize the grabbing and positioning for the sample trays and the needle handling inside of the Multisampler. The sample coupler moves the sample container from the sample hotel which stores all the samples and place it on the central workspace. Then the needle coupler of the Z drive takes over and grabs the needle assembly from the needle station and performs the analytical procedures inside of the Multisampler. Due the uncoupled needle design, the robot can do other liquid handling jobs during the analysis.
The multisampler employs an active vial/plate pusher mechanism to hold down the vial or the plate while the needle is drawn back from the sample vessel (a must in the case a septum is used). This active vial/plate pusher employs a sensor to detect the presence of a plate and to ensure accurate movement regardless of plate used. All axes of the transport mechanism are driven by very fast BLCD motors. Optical encoders ensure the correct operation of the movement.
The standard configuration of the Multisampler uses either a 40 µL or a 100 µL metering device. With this instrument setup, it is possible to inject a maximum volume of 20 µL or 100 µL. For higher injection volumes, additional hardware modifications are required. For minimum internal carryover, the entire injection flowpath is always flushed by the mobile phase.
In addition, you have two different possibilities to reduce the carryover. The first is the external needle wash. In the Standard configuration, the needle flush station is equipped with a peristaltic pump to wash the outside of the needle. This reduces already low carryover for very sensitive analysis. The bottle containing the mobile phase for the wash procedure will be located in the solvent bottle cabinet. Produced waste during this operation is channeled safely away through a waste drain. In the Multi-Wash configuration, the external needle wash will be done by a micro piezo pump combined with a solvent selection valve, where you can select between three different solvents. If this is not sufficient to reduce the carryover, there is an additional and perfect way to achieve the lowest carryover in the Multi-Wash configuration by using the integrated flush pump. This high-pressure pump can also select between three different solvents and is capable of reducing the carryover to a minimum by using the seat backflushing. The flush pump outlet capillary is connected to port 4 of the Multisampler's injection valve, which normally holds the waste line. If the Multisampler is in bypass mode, the flush pump connects to the needle seat and can flush backwards through the needle seat into the waste line attached to the needle seat outlet port.
The six-port (only 5 ports are used) injection valve unit is driven by a high-speed hybrid stepper motor. During the sampling sequence, the valve unit bypasses the Multisampler, and connects flow from the pump to the column directly. During injection and analysis, the valve unit directs the flow through the Multisampler which ensures that all of the sample is injected onto the column, and that the metering unit and needle are always free of sample residue before the next sampling sequence begins.
The Cooling Control of the vial/plate temperature in the Multisampler is achieved using an additional Agilent Sample Thermostat module. The chiller unit is a micro compressor-based refrigerator. A fan draws air from the central workstation above the sample container of the Multisampler. It is then blown through the fins of the cooling module, where it is cooled according to the temperature setting. The cooled air enters the Sampler Hotel through a recess underneath the special designed base plate. The air is then distributed evenly through the Sample Hotel ensuring effective temperature control, regardless of how many sample containers are in the drawer. In cooling mode, condensation is generated on the cooled side of the Sample Thermostat. This condensed water is safely guided into a waste bottle for condensed water that is located underneath the working bench.
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id: 3803204235