Introduction:

Establishing a quality management system in a clinical laboratory, which includes internal quality control, allowed obtaining the total measurement error (TME), which was less than the total acceptable error (TE<TEa), thus demonstrating the validity and clinical utility of the method used. The objective of this study was to evaluate sigma performance in electrolyte determination over a semester. To achieve this, the clinical laboratory used the total acceptable error (TME), trueness (bias), and imprecision (coefficient of variation).

Material and methods:

All guidelines were followed to implement the CLSI EP 15-A3 protocol (Standardization protocol approved in its third version, by the CLSI, to verify precision and estimate bias.) in the Easy Lite Plus ® equipment (registered trademark equipment), with the aim of checking the repeatability of the data obtained through its ion selective method for the electrolyte trio. To verify the reproducibility of the data, the data were analyzed monthly for a semester and represented in decision graphs of the method.

Results:

Results exceeding six sigma (6 σ) of world-class performance were achieved over a five-day period. A semiannual evaluation of sigma performance was also conducted, achieving acceptable results based on the selected quality requirement.

Discussion:

The use of strict quality specifications reduces sigma levels and provides a more accurate and authentic view of test quality. Verifying analytical procedures promotes a culture of quality and encourages continuous improvement in analytical practice.