Reagent strip

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.

Reagent strips for urinalysis, manufactured by Bayer Healthcare. Each strip contains reagent patches for the testing of glucose, bilirubin, ketone (acetoacetic acid), blood, pH, and protein. See the package insert for exact reagent compositions. 

Hydrometers (urinometers) from 1.00 to 1.40 specific gravity Clinistix (50 reagent strips/bottle)... 

These are obtainable from Ames Co., Division Miles Lab. Inc., Elkhart, Indiana, 46515. Instead of the individual Stix, you may purchase 4 bottles of multipurpose Labstix (100 reagent strips/bottle). 

The oldest example of an integrated dry reagent chemistry for quantitative analysis of a metabolite is the Dextrostix reagent strip (Miles Dia ostics) for whole blood glucose analysis. The cross section of the element is illustrated in Fig. 8a. The detection chemistry is the well-known glucose oxidase-peroxidase procedure. Approximately 50 pL of whole blood is applied to the surface of the... 

Fig. 8. Cross sections and chemistries of test elements for blood glucose analysis, (a) Miles Diagnostics, Inc., (Dextrostix reagent strips), b) BMC, and (c) Fuji.

Fig. 9. Features of the Answer (a) reflectance photometer and (b) reagent strip.

Fig. 13. (a) The cross section and chemistry of the Seralyzer reagent strip (Miles Ditignostic, Inc.) for serum potassium determination, (b) Comparison of strip and gravimetric analyses for potassium. 

Fig. 14. (a) The cross section of the Seralyzer reagent strip (Miles Diagnostics, Inc.) for analysis of serum theophylline, (b) The kinetic profile of reacting strip where the change in the reflectance function (K/S) is monitored as a function of time for several concentrations of theophylline, (c) The relation of theophylline concentration to the rate of change in the reflectance function d(K/S)ldt]. 

A derivative of umbelliferyl-p-galactoside serves as a fluorogenic substrate for E. coli (3-galactosidase in this system and solid-phase reagent strips based on this method have been developed. 

Walter, B. Greenquist, A.C. Howard, W.E., III. Solid-phase reagent strips for detection of therapeutic drugs in serum by substrate-labelled flourescent immunoassay. Anal. Chem. 1983, 55, 873-878. 

Chu, A.H. and Lopatin, W. (1986). Application of pattern-recognition techniques in wavelength selection for instrumentally read reagent strips. Clin. Chem. 32, 1666-1671. 

Multi-test reagent strips of the Cobas Ready system... 

The reagent strips are packaged in aluminium foils which also contain a drying agent. They can be kept at room temperature, except for the creatine kinase (CK) and the alkaline phosphatase (ALP) test which have to be refrigerated. The shelf-life is one year. 

During the measurement or calibration, these photodiodes measure the light reflected from the reagent strips or the standard reflectance plates previously moved to the measuring position. The output of each photodiode is taken out as short-circuited current, which is then converted to voltage by an A/D convertor. 

The optical unit is thermally controlled at a temperature which is 0.5-l°C higher than that of the reagent table, in order to keep the reagent strip at a constant temperature and thus to eliminate potential variations of the measured results due to temperature fluctuations. 

To guarantee the one-year shelf-life of the reagent strips, it is advised to recalibrate the analyser every three months to compensate the variation of reagent sensitivity. A caUbration must also be performed if ... 

R44 Wenk, R.E., Lustgarten, J.A., Byrd, C., Patterson, D. and Hall, B. (1986). Evaluation of reagent strip reflectometry for hemoglobin and whole blood glucose. Clin. Chem. 32, 1112, Abstr. 307. 

R145 Gubata, P. and Lefebvre, R.C. (1989). Comparison testing of lot to lot variance in the Reflotron dry reagent strip method of cholesterol measurement. Clin. Chem. 35, 1098, Abstr. 155. 

R185 Kropf, J. and Gressner, A.M. (1990). Evaluation of the Reflotron dry reagent strip method for pancreatic isoamylase determination. Clin. Chem. 36, 1206, Abstr. 1186. 

Plasma samples drawn with disodium EOT A, sodium oxalate, trisodium citrate, or sodium fluoride, exhibit variable inhibition in the reagent strip assay and should be avoided. 

S27 Tyhach, R.J., Rupchock, P.A., Pendergrass, J.H., Skjold, A.C., Smith, P.J., Johnson, R.D., Albarella, J.P. and Profitt, J.A. (1981). Adaptation of prosthetic-group-label homogeneous immunoassay to reagent-strip format. Clin. Chem. 27, 1499-1504. 

Gregory, J. and Lester, E. (1982). Drug interference with reagent strip method for measuring urea. Lancet 8295,443. 

Anderson, R., Wilsey, C. and Grove, J. (1983). A solid-phase reagent strip test for the colorimetric determination of serum triglycerides on the Seralyzer. Clin. Chem. 29, 1247, Abstr. 516. 

Burd, J.F., Ellis, P.B., Greenquist, A.C., Li, T.M., Morris, D.L., Rupchock, P.A., Sommer, R.G., Tyhach, R.J., Walter, B. and Zipp, A.P. (1983). Measurement of theophylline with the substrate-labeled fluorescent immunoassay and apoenzyme reactivation immunoassay system in solution and in solid phase reagent strips. In Avrameas, S. et al. (Eds), Immunoenzymatic Techniques Proc. 2nd Int. Symp. Immunoenzymatic Techniques, Cannes, 16-18 March. Elsevier Science Publishers, Amsterdam, pp. 239-246. 

Stevens, J.F., Tsang, W. and Newall, R.G. (1983). Measurement of the enzymes lactate dehydrogenase and creatine kinase using reflectance spectroscopy and reagent strips. J. Clin. Pathol. 36, 1371-1376. 

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