Isothermal titration microcalorimeter apparatus and method of use
An automatic pipette assembly for an isothermal titration micro calorimetry system, comprising a pipette housing, a syringe with a titration needle arranged to be inserted into a sample cell for supplying titrant, and a linear activator for driving a plunger in the syringe, the titration needle is rotatable with respect to the housing and is provided with a stirring paddle arranged to stir fluid in the sample cell, wherein the automatic pipette assembly comprises a stirring motor for driving the rotation of the titration needle. There is also provided an isothermal titration micro calorimetry system.
1. An automatic pipette assembly for an isothermal titration micro calorimetry system, comprising a pipette housing, a syringe with a titration needle arranged to be inserted into a sample cell for supplying titrant, and a linear activator for driving a plunger in the syringe, the titration needle is rotatable with respect to the housing and is provided with a stiffing paddle arranged to stir fluid in the sample cell, wherein the automatic pipette assembly comprises a stirring motor for driving the rotation of the titration needle.
2. The automatic pipette assembly of claim 1 , wherein the stirring motor is a direct drive motor with a hollow rotor arranged concentric with the titration needle.
3. The automatic pipette assembly of claim 1 , wherein the stirring motor drives the titration needle for rotation by a rotation transmission arrangement.
4. The automatic pipette assembly of claim 1 , wherein the syringe is rotatable with respect to the housing and the titration needle is non-rotatably attached to the syringe.
5. The automatic pipette assembly of claim 4 , wherein the syringe is detachably arranged in a rotation frame within the pipette housing.
6. The automatic pipette assembly of claim 1 , wherein the linear activator comprises a stepper motor arranged to drive a threaded plunger, the pipette assembly further comprises position sensors for detecting two predetermined positions of the threaded plunger.
7. An isothermal titration micro calorimetry system comprising the automatic pipette assembly of claim 1 .
8. The isothermal titration micro calorimetry system of claim 7 , further comprising a pipette controller arranged to control the linear activator and the stirring motor of the pipette assembly, wherein the linear activator comprises a stepper motor arranged to drive a threaded plunger, the pipette assembly further comprises position sensors for detecting two predetermined positions of the threaded plunger, and wherein the pipette controller is arranged to register the two predetermined positions of the threaded plunger and to determine the pitch of the threads of the plunger from the number of steps performed by the stepper motor to move the threaded plunger between said positions.
9. A micro titration calorimetry system comprising an automatic pipette assembly with a titration needle arranged to be inserted into a sample cell for supplying titrant, and a pipette guiding mechanism arranged to guide the pipette assembly between and into at least two positions of operation, wherein a first position of operation is a pipette washing position wherein the titration needle is inserted in a washing apparatus, and a second position of operation is a titration position wherein the syringe is inserted into the sample cell for calorimetric measurements.
10. The micro titration calorimetry system of claim 9 , wherein the washing apparatus is arranged to allow filling of titrant to the pipette assembly after washing of the pipette assembly is completed.
11. The micro titration calorimetry system of claim 9 , further comprising a third position of operation in the form of a titrant filling position, wherein the titration needle is inserted in a titrant source.
12. The micro titration calorimetry system of claim 9 , wherein the guiding mechanism is of rotational type, and the positions of operation are arranged at equal distance about the centre of rotation of the guide assembly but at different angular positions, wherein movement of the pipette assembly in the vertical direction is restricted to the angular positions of the positions of operation, and wherein rotational movement of the pipette assembly between the angular positions only is permitted when the needle is fully retracted from respective positions of operation.
13. The micro titration calorimetry system of claim 9 , further comprising a position sensor arranged to register when the pipette assembly is positioned at one of the positions of operation, and wherein the associated operation is restricted by the state of the position sensor.