Validation of the biochemical method of determining the ammonia level in the biological liquid samples as a tool for providing the quality of hyperamonemia diagnostics

Abstract

Materials and methods. The object of the study was a standardized method for determining the level of ammonia. An “Ammonia NH 3 ” reagent manufactured by Randox, USA, and the known concentration of “Ammonia ethanol control – level 2” manufactured by Randox, USA as a control serum were selected for the study. The measurements were carried out on an Express Plus automatic biochemical analyzer manufactured by Bayer Corporation, Germany. When process ing the research results the descriptive statistics indicators were used, and a number of statistical evaluations were carried out. Results. The validation procedure consists of several stages. At the premises of the Laboratory of Clinical Diagnostics of the CDC of the NUPh the protocol and the validation report were developed to assess the suitability of the method for determining the concentration of ammonia in biological liquids by the enzymatic UV method on an Express Plus auto matic biochemical analyzer. Validation was carried out using reagents and control material manufactured by Randox, USA. The following validation characteristics of the method were determined: specificity, convergence and reproduc -ibility, correctness, measurement uncertainty. The assessment of the intermediate convergence and reproducibility of the ammonia determination method when working on the analyzer by two laboratory assistants of the same qualifica tion indicates the absence of gross errors in the operation of the device and statistically important differences during measurements. The assessment of the method correctness using the control material has proven that the systematic error is not significant (according to the given criterion of acceptability). Thus, this method provides the accuracy of measurements within the laboratory. The calculation of the expanded uncertainty has shown that the obtained values of the ammonia level can be considered accurate and reliable. Conclusions. The validation of the method for determining ammonia in the human blood by the enzymatic method has proven that this method has performance characteristics that meet the regulated ones, satisfies the established criteria, and the parameters measured correspond to the appropriate ones.