Reagent carrier

Apart from being employed solely as solvents, ILs can also be used as reagent carriers (TSlLs, task-specific ionic liquids). An efficient system that uses ILs as solvents and anchoring/acylating reagents for the CAL B-catalyzed separation of racemic alcohols is shown in Scheme 5.17 [69]. 

Figure 6.3 Diagrammatic representation of the dry reagent strips known as reagent carriers, which are used in the Boehringer Reflotron System for the chemical analysis of blood samples. Red blood cells are removed in the separating layer and the plasma passing into the glass fibre transport layer is analysed. The magnetic code carries information about the analytical procedure.

The reagents, carrier gases and auxiliary materials must be as pure as possible. 

A number of linear, non cross-linked soluble polymers have been investigated for their use as supports for biopolymer synthesis and as reagent carriers in organic synthesis 157). The motivation behind all these attempts have been mainly the circumvention of the diffusion and reactivity problems often encountered in the heterogeneous solid phase reactions. 

The specular reflection will not be dealt with here in detail, since it is unsuitable for the evaluation of reagent carriers. 

In the following, the description will be confined to the relationship that holds good for the dry reagent carriers, for which an infinite layer thickness is assumed. This relationship is expressed by the theory of Kubelka and Munk ... 

The coefficient of extinction r mentioned here is approximately comparable but not identical with the coefficient of extinction in Beer-Lambert s law. r is dependent on an interaction between the absorbing molecules and the reagent carrier matrix. 

In absorption photometry the pathlength of the cuvette is usually fixed. In conventional clinical chemical methods a dilution of the sample is necessary both to run the assay under optimized conditions and to make sure that the developed color of the reaction product is within the measurable absorbance range of a spectrophotometer. The thickness of the reagent carrier in reflec-tometry which is calculated by means of the Kubelka-Munk theory, is assumed to be infinite and hence of negligible significance. Hence, the linear range in reflection spectroscopy may be expected to exceed that of absorption spectroscopy with a consequential reduction in the frequency of sample dilution prior to measurement. 

In systems where there are optically active reaction products held in transparent reagent carriers between the incident light and the reflecting background (e.g. Kodak or Fuji systems), the Kubelka-Munk transformation is... 

Greyson, J, (1981). Problems and possibilities of chemistry on dry reagent carriers. J. Automatic Chem. 3, 66-71. 

The following chapters present commercially available instrument systems. Both the instruments and the relevant reagent carriers or slides are described with detailed data on the reliability of each method and each reagent carrier. Attention is also focussed on possible errors and interferences when performing an analysis. 

The data sheets have been designed as uniformly as possible, but this was not always possible due to differences in the structure of the individual reagent carriers or slides. The common features, however, are explained below. 

Structure and composition of the reagent carriers or slides. The chemical and in some cases also the physical composition is given according to the best available data. The structure of the reagent carriers used with the Stratus system is uniform throughout and is therefore not stated for each individual carrier. 

Fuji evolved their system on a multilayer film technique basis. The primary goal has always been the determination of components of the blood without requiring external separation of serum or plasma (i.e. a centrifuge). Hence, it was necessary to develop a layer that would retain the coarse corpuscular blood components (erythrocytes, leukocytes etc.). The principles of the construction of the slides and the method of measurement are in accordance with the instructions that have been given for the use of Kodak instruments (see p. Ektachem system). The instrument is not available in Europe or on the American continent. It has also not yet been presented at exhibitions or congresses. So far, only the slides (reagent carriers) for the measurement of glucose and urea have been described in detail (D1-D6). 

Influence exercised by the sample volume (Dl, D3) No influence on the method was observed between 7 and 11 xl (standard value 10 xl). Sample volumes < 7 xl yield lowered glucose concentrations. It is not possible to apply more than 11 pi, since otherwise the blood will run over the reagent carrier (slide). 

Influence exercised by the volume of the sample (D4) Errors of volume are tolerable between 8-12 il. Volumes < 8 il will yield too low urea values. Volumes > 12. il cannot be applied to the slide overflow will occur and the reagent carrier will be soiled. Measurement must then be discontinued. 

Approximately 10-11 al of the sample or specimen to be assayed (serum or plasma, and for some chemistries urine or cerebrospinal fluid) are applied to the reagent carrier slide. The specimen will diffuse into the slide within a short time, where it reacts with a reagent that is present in a gelatine or agarose matrix. The dye that forms can be measured reflectometrically. The electrolytes (sodium, potassium, chloride and carbon dioxide) are assayed by means of single use ion-selective electrodes. 

E238 Wisser, H., Knoll, E., Ratge, D. and Hafner, F.W. (1985). Dry reagent carriers - an analytical alternative. Poster presented at the Annual Meeting of the Deutsche Gesellschaft fur Klinisch Chemie in cooperation with the Association of Clinical Biochemists and the Societe Fran(aise de Biologie Clinique, Mannheim, 25-28 September. 

E354 Keller, H. (1987). Analysis with solid phase reagent carriers. Med. Prog. Tech. 13,5-19. 

The Reflotron system consists of the reagent carrier, reflection photometer and an air displacement pipette or applicator. It is easy to operate. The required blood sample is obtained by puncturing the finger pad or ear lobe with... 

Fig. 36. Reagent carriers of the Reflotron system a natural view b schematic representation.

The reagent carriers are produced batchwise. A batch-specific functional curve is set up for each batch and entered as magnetic code on the carrier... 

This routine calibration (curve adjustment) is performed for every reagent carrier lot. A total of 30 tubes is drawn from the beginning and the end of every sealed lot role and randomised. 2-4 reagent carriers each are measured by five different instruments with each of the 15 calibrators, so that 10-20 reflectance values are obtained. These values enable calculation of the regression with the help of the functional curve that is best suited for the test. Plotting the functional curves is part of the manufacturing process. Final release of the new lot is effected only after testing with control samples (human material) in the control laboratory. 

Storage life of the reagent carrier At temperatures between +2°C and +30° C stable up to the imprinted date of expiry if stored in closed containers. 

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