AUTOMATIC CHEMISTRY ANALYZER
This invention related to inventions and disclosures which are the subject of Application Nos. 07,322,814 filed Mar. 13, 1989; 07/322,802 filed Mar. 13, 1989; 07/322,810 filed Mar. 13, 1989; 07/322,811 filed Mar. 13,1989; 07/322,812 filed Mar. 13,1989; and 07/322,813 filed Mar. 13, 1989; All these patent applications are filed contemporaneously with the present application and the contents of them all are incorporated by reference herein.
This invention relates to the field of automatic analytical instruments. More particularly, the invention is concerned with automatic chemistry analyzer instruments for clinical use. In such instruments, these are
sample carousels and sample handling systems.
Different clinical analyzers for automatic chemistry analysis are known. One particular kind uses a plurality of individual analysis modules having open reaction cups. An automated sample probe withdraws sample 25 fluid from samples in containers carried on a carousel. Selected volumes of the sample are distributed to analysis module cups in accordance with the tests selected by the instrument operator.
A different kind of analyzer uses a flow cell through j0 which different and reagent flows together with samples for determination of electrolytes in the fluid sample. Usually, four electrolytes, namely, sodium potassium, chloride, and CO2 are measured. In such analyzers, a pick-up probe extends vertically through a shear 35 valve to aspirate the fluid sample from a sample cup aligned with the probe. The probe is withdrawn into the valve and the lower portion of the valve closes. Diluent from a diluent source flows into the valve, is mixed with the sample from the probe and flows to a flow analysis 40 module.
Each of these different kind of analyzers have their unique advantages in analysis of fluid samples. The flow cell analyzer provides simplified fluid handling and minimizing reagent consumption. 45
The present invention is particularly concerned with flow cell analyzer systems and means for improving the operation, movement, and visibility of the various components and fluids. One of the difficulties in flow cell analyzers is the problem in monitoring the flow stream 50 through the flow cell. Moreover, the flow cell is often located in a manner that is not easily physically accessible or visible which causes difficulty in maintenance and troubleshooting procedures which increases costs of operation. Moreover, another difficulty associated 55 with the flow cell is the difficulty of injecting sample from the sample cup into an injection cell and draining fluid from the flow cell and subsequently from the system. Multiple pumps and wash facilities are often needed to ensure effective injection and drainage. These 60 considerations increase costs and maintenance requirements.
A further problem arises from the arrangement for injecting reagents into the flow cell. Prior art methods include the use of peristaltic/multistage pumps related 65 so as to develop different pumping ratios. It has been relatively difficult to ensure accurate tolerances with the relative ratios of fluids to be pumped in the system.
Other problems which arise are due to electrical noise within the system, and the need to minimize this noise to ensure accurate results. Different techniques have been employed, including a strategic location of the ground for the system.
Many other characteristics exist in the prior art systems which are in need of improvement. These include the sample handling mechanism, means for moving samples from sample reaction cups to an injection cell, means for and the number and nature of the motive means and the electronic operations. All of these characteristics in the prior art have various limitations.
The present invention solves problems, and improves on the drawbacks posed, in the prior art by providing an automatic chemistry analyzer with substantially enhanced characteristics.
According to one aspect of the invention, the analyzer for measuring electrolytes in a fluid comprises an instrument housing, a flow cell in the housing, the housing having selectively movably panels formed at least in part by the panels. There is means for passing fluid through the flow cell between an injection cell and a drain. The flow cell is mounted in the housing for visibility, so that an opening of, or moving of, the panels from the housing a substantial length of fluid flow through the flow cell is selectively visible from the location from which the panels are opened or moved.
Preferably, the flow cell is formed between a pair of molded clamping plates of at least partly transparent material thereby to permit visibility through the cell. The flow cell includes electrodes removably plugable into the cell from the rear. This is from behind the flow cell relative to the location of the panels in the housing.
According to another aspect of the invention, there is an injection cell for receiving fluid sample. Means for washing the injection cell and means for diluent to the cell are provided whereby there is simultaneous dilution of the sample and washing of the probe.
Preferably the injection cell is mounted together with a waste basin, the waste basin and injection cell being part of a unit. The waste basin empties into the drain and the drain is located below the flow cell, the flow from the waste basin to the drain being under gravity.
In yet a further form of the invention, there is provided fluid sources for the flow cell, the fluid sources being selectively reactive or non-reactive with the fluid sample to permit analysis of the sample. A pump is provided for the fluid sources and sample to the flow cell, the pump including discrete syringes between each respective fluid source and the flow cell. The syringes are collectively band driven by motive means, and selectively are of different volume such that different volumes of fluid can be pumped from the syringes to the flow cell. The different volumes of the syringes are relatively predetermined and as such the syringe-band system forms a ratio pump.
In yet a preferred further aspect of the invention, the solution ground for the system is provided on the fluid sample line located close to the measuring electrode. This is preferably at the bottom of the flow cell, namely, at the inlet of the sample/internal reference and diluent into the flow cell.
In a further preferred aspect of the invention, the sole motion for the probe for transferring fluid from the fluid sample to the injection cell is limited to vertical move