Biomedical subjects

P Maibaum

Publications and source records attributed to P Maibaum.

3 recordsLinked to original sources

PubMed1990

Analyses with the KODAK-Ektachem. Accuracy control using reference method values and the influence of protein concentration. Part I. Electrolytes.

The reliability of electrolyte determinations with the Ektachem 700 was evaluated by various means including the use of reference method values. The influence of protein concentration, which may alter the viscosity and hence the speed of diffusion, was systematically investigated by using samples of varying protein concentration obtained by ultracentrifugation. Calcium. The mean bias between Ektachem results and reference method values of 9 control sera was -7.3%. In a comparative study with native sera a negative bias was not obtained. The accuracy was independent of the protein concentration. Chloride. The mean bias was -0.1% compared with reference method values. As might be expected, the difference between chloride values with Ektachem--using a "direct" ion-selective electrode--and determinations by coulometry increased with increasing protein concentrations. Magnesium. A negative bias (-5.0%) was obtained in accuracy control with reference method values, and to a smaller extent in a comparative study with native sera. An influence of the protein concentration on the magnesium determination was not observed. Phosphate. Accuracy control by method-dependent assigned values and a comparative study with native sera showed a positive bias. Ektachem results depend on the protein concentration. At 120 g/l protein the bias was +13.6%. Potassium. The mean bias, with respect to reference method values, was -1.2%. At high concentrations of proteins of "normal" composition, Ektachem results agree with measurements by flame atomic emission spectrometry; in paraproteinaemic sera the values are higher. Sodium. The mean inaccuracy was 3.3%, compared with reference method values. The dependence on the amount and composition of the total protein was similar to that found for potassium analysis.

Blood Chemical Analysis↗

PubMed1990

Analyses with the KODAK-Ektachem. Accuracy control using reference method values and the influence of protein concentration. Part II. Substrates.

The reliability of the determination of the most common substrates with the Ektachem 700 was evaluated. Accuracy control was performed in various ways including the comparison of results with reference method values. The influence of protein concentration was investigated systematically using sera containing varying amounts of protein obtained by ultracentrifugation. Bilirubin. Deviation from the reference method values was within limits of the guidelines (Dt. Arztebl. 85 (1988) B517-B532). The influence of protein concentration was negligible. Cholesterol. The results agreed well with the reference method values. The method was not influenced by different protein concentrations. Creatinine. The results were in good agreement with reference method values, when the method was calibrated with the primary assigned values of the calibrators. At high protein concentrations, the results were higher than those of the comparative method. Glucose. The mean deviation from the reference method values was 1.0%. There was a clear positive bias at high protein concentrations. Protein. The results from the Ektachem deviated from the reference method values by -6.8%. Total glycerol (triacylglycerols). In the analysis of control sera, the Ektachem values differed greatly (+32.1%) from the reference method values. This difference was not found in a comparative study with native sera. At high protein concentrations the Ektachem results were higher than those of the comparative method. Urea. The results were lower than the method-dependent assigned values (-16.6%). This deviation was not observed in a comparative study with native sera. Interference by protein was not observed. Uric acid. In accuracy control with reference method values, a small bias was observed (+3.3%), which increased at high protein concentrations.

Bilirubin↗

PubMed1985

A comparison of reference method values for sodium, potassium and chloride with method-dependent assigned values.

The concentrations of sodium, potassium, and chloride in various control sera were determined by reference methods. The reference method values were compared with the corresponding method-dependent assigned values. Sodium: Measurements by flame photometry and ion selective electrodes differed on the whole by less than 1% from the reference method value; determinations by photometry differed, however, by -4.7%. Potassium: The mean bias was -1.2% with flame photometry and -0.4% with ion selective electrodes, whereas nephelometric procedures differed by -1.9 or -4.8%. Chloride: Satisfactory agreement was obtained with values given for ion selective electrodes (-0.3%), for some coulometric procedures (-0.7 and 0.4%), and photometric determinations using mercury rhodanide (-0.5 and +0.7%). Values for mercurimetric titration and for photometric determinations using mercury 2,4,6-tri-(2-pyridyl)-s-triazine differed by + 2.5 and + 1.8%. Proposals concerning the allowable deviation from reference method values are discussed.

Chlorides↗