The dry reagent systems consist of paper impregnated with the components of clinical chemical assay systems mounted on a plastic support." The placement of exactly 30 !Jol of a prediluted serum specimen (depending on the analyte being tested) is made on the reagent area and initiates the reaction, which then results in the formation of colour which is proportional to the concentration of the particular analyte. The colour intensity is measured by reflectance spectroscopy. The reaction is thermostatically controlled at 37°C. 1982; 19: 214-223 Evaluation of a quantitative solid phase reagent system for determination of blood analytes Experiences with the analytes: LDH, bilirubin, BUN, glucose, and uric acid LOTHAR THOMAS,· WOLFGANG PLISCHKE,t AND GUNTHER STORZ Ann Clin Biochem From the "Central Laboratory of the Nordwestkrankenhaus, 6000 Frankfurt, and the t Scientific DepartmentMiles GmbH, 6000 Frankfurt 71, West Germany SUMMARY In the first part of the Seralyzer system evaluation the precision and accuracy was studied with a total of 1245 clinical specimens, various commercial control sera, and pooled human sera. The calculated overall precision (between-run, and within-run) and day-to-day precision (% CV) was found to be within 3·0 to 5·4 for glucose, 2· 8 to 7·1 for BUN, 1· 5 to 6·2 for uric acid, 5·3 to 7·5 for bilirubin, and 3·2 to 8·6 for LDH. The clinical values are in agreement with values from respective comparative methods, as indicated by the regression statistics. The analysis of Seralyzer accuracy data using quality control sera showed in some cases a between-method difference. Supporting studies simulating additional important clinical situations showed that the clinical values for BUN, glucose, and uric acid of approximately 200 specimens from the emergency ward correlated with the respective comparative method values. In this phase of the study we verified that the instrument calibration was stable for a 24-hour period and that there is no effect of module (test) change on precision of Seralyzer determinations. The intra-and inter-laboratory performance in general practitioners' laboratories could be demonstrated using quality control sera.

Quantitative measurement of blood constituents (glucose, uric acid, urea-N) on dry reagent carriers was compared with corresponding wet-chemical methods. There was a good correlation (r greater than 0.95) and excellent linear regression with small scatter between the two methods for the three constituents. The dry test has proved to be a precise, simple, rapid and economic method, especially suitable for the practitioner and emergency laboratory.

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Blood sugar levels in 228 EDTA-treated venous blood samples were measured in the laboratory by a new test-strip (Visidex) and the hexokinase reference method. There was good agreement between the two, with a linear correlation of r = 0.92 and a regression line with a slope of 0.98. 97.8% of all values deviated by less than one concentration range from the reference values. At low glucose concentrations the median of the absolute differences between the two methods was 9.5 mg/dl. Over the whole concentration range of 20-800 mg/dl the mean deviation from the reference values was between 14.4 and 32.6 mg/dl. The results indicate that the Visidex test-strip method is suitable for the visual estimation of blood sugar values.