Measuring and testing – Sampler – sample handling – etc. – Capture device
Patent
1986-02-12
1987-12-29
Tokar, Michael J.
Measuring and testing
Sampler, sample handling, etc.
Capture device
7386463, 7386481, 422100, G01N 114
Patent
active
047152370
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus as set forth in the classifying portion of claim 1. Apparatuses of that kind are used inter alia in volumetric analysis. Conventional constructions are for example piston burettes, as are described for example in EP-A-96 088. The piston can be actuated manually or by way of an auxiliary drive. A precise indication of the volume in the chamber in dependence on the position of the piston is nowadays generally provided electronically.
EP-A-1137 discloses a burette-like apparatus in which a cylinder chamber can be increased in size in a stepwise fashion by actuation of a piston or plunger, while various connecting lines can be selectively short-circuited to the chamber. Qualitative analysis of the liquid is effected by ejection into a reaction measuring chamber outside the cylinder chamber.
All known piston burettes suffer from the disadvantage that the chamber volume thereof cannot be increased in size starting from zero and that it is not possible for the entire chamber content to be forced out of the chamber. That is linked to the fact that, even when the apparatus has valves or taps which are arranged directly on the chamber, there always remains a space from which liquid cannot be ejected with the piston. Depending on the purpose of use of the burette, that residual amount may have a detrimental effect on the measurement result in qualitative and quantitative respects. That is an aspect of significance particularly when the chamber of the burette itself is used directly as a reaction chamber. So that in that respect the chamber can be filled in a given sequence with various reagents, and auxiliary and measuring solutions, or can be flushed out in a similar manner, it is absolutely necessary for precisely definable quantities to pass into the chamber while, upon ejection of the liquid, it is essential that no residual amounts should remain in the chamber, which would adversely affect a subsequent measurement operation.
It is therefore an object of the present invention to provide an apparatus of the kind set forth in the opening part of this specification, in which the chamber can be increased in size starting from zero and which can be completely emptied out without a residual amount remaining behind. A further object of the present invention is for as many ducts as possible to be taken into the chamber in a simple fashion from the design point of view, which ducts can be selectively connected to the chamber in such a way that, on changing from one duct to another, no residual amounts of liquids, which cannot be registered by the measuring device, remain in the chamber. In addition the invention seeks to make it possible easily to automate quantitative and/or qualitative analysis operations of that kind.
According to the present invention, that object is attained by an apparatus having the features recited in the characterizing portion of claim 1.
By virtue of wall portions of the chamber itself being formed as a shut-off or closure member, a given amount of liquid can be accommodated by the chamber, starting from a zero chamber volume, in a surprisingly simple fashion, and it is possible to change from a first liquid to a second liquid without an uncontrollable residual amount of the first liquid remaining behind in the chamber. That principle may be embodied in a particularly advantageous manner if the chamber is formed by a cylinder in which a piston is disposed for varying the volume of the chamber, and if the shut-off member is formed by a wall portion which is disposed at the cylinder end and which is displaceable relative to the cylinder casing. In that way the shut-off member may be actuated with the piston in any position. When the piston bears against the cylinder end portion, then the volume of the chamber is equal to zero. When the piston is moved away from the cylinder end portion, then each position of the piston exactly corresponds to a precisely definable amount of liquid in the cylinder, more specifically even when the shut-off member is closed or whe
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Kaempf Karl
Richter Wolfgang
Zaehner Paul
Metrohm AG
Raevis Robert R.
Tokar Michael J.
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