Measuring and testing – Sampler – sample handling – etc. – Analyzer supplier
Patent
1996-11-21
1998-07-14
Raevis, Robert
Measuring and testing
Sampler, sample handling, etc.
Analyzer supplier
422 82, G01N 3508
Patent
active
057807540
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an analysis method, in which several samples are passed in succession through a reaction channel to a detector, and at least one reagent is introduced into the reaction channel for reaction with the samples. The invention relates furthermore to an analysis apparatus having a sample feed duct, at least one reagent feed duct, a pumping device for sample and reagent, and a reaction channel and a detector.
There is a constantly growing need for chemical analysis in many areas. The area of environmental protection can be quoted as an example. Here, for example, when bodies of water are being monitored, water samples have to be removed continuously from the body of water and examined for contaminants. The operation of sewage treatment plants, for example, the injection of air, is effected in dependence on specific substances contained in the water to be purified. Such analyses have to be performed at frequent intervals, with the result that not only is the number of analyses large, but these analyses also have to be carried out as quickly as possible. The same applies to the disciplines of medicine and environmental analysis. In large laboratories, as a rule very many samples have to be examined. This can no longer be carried out using conventional manual methods, in which the sample to be examined is mixed with reagents, for example, in a beaker, and a resulting reaction product is recorded and evaluated for type and quantity. An additional complicating factor is that normally it is not just a single reaction step that has to be carried out but a number of reaction steps. This not only requires manpower, but also the provision of correspondingly large laboratory areas in which the samples to which reagents have been added can be stored in the interim until they have reacted and/or until the reaction product has been evaluated. Moreover, relatively large amounts of samples and reagents are necessary for the manual methods, which renders waste management difficult.
For those reasons, a start was made some decades ago on the development of continuous or semi-continuous methods which could function with smaller sample sizes and with fewer reagents. Because these methods have been "mechanized" it is also possible to examine a larger number of samples in the same time. The methodology has been retained here, that is to say, the sample is mixed with one or more reagents and the resulting reaction product is detected using a detector.
U.S. Pat. No. 2,797,149 and U.S. Pat. No. 2,879,141 describe a so-called "Segmented Flow Analysis" (SFA), that is to say, an analysis method in which successive sample segments are separated by air bubbles in the sample duct. After mixing each sample segment with one or more reagents, the reaction product can be evaluated separately in each segment. By choosing the length of the reaction channel, the time available for the reaction can be adjusted. The use of air bubbles in the reaction channel to separate the individual samples produces a compressible fluid column, however, so that the flow speed, and thus the reaction time, cannot be accurately monitored.
U.S. Pat. No. 4,022,575 and DE 28 06 157 C2 disclose a more recent method, which is known as "Flow Injection Analysis" (FIA). Here, the individual samples are introduced at specific distances apart into a carrier fluid so that successive samples are always separated by a segment of pure carrier fluid. This carrier fluid partly charged with samples is then mixed with the reagent or reagents. Evaluation of the reaction product is effected in a similar manner by a detector, which records the reaction product according to type and/or quantity. Because the samples are diluted by the carrier fluid within a sample segment on the one hand, and because of the transition between a segment comprising a sample-carrier fluid mixture and a segment of pure carrier fluid on the other hand, which leads to further distortion of the sample concentration at the start and the end of each sample segment,
REFERENCES:
patent: 4486097 (1984-12-01), Riley
patent: 4625569 (1986-12-01), Toei et al.
patent: 4908187 (1990-03-01), Holmquist et al.
patent: 5633168 (1997-05-01), Glasscock et al.
Karlberg Bo
Ploug Ole
Danfoss A/S
Raevis Robert
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