Selection and Preliminary Measurements of Optical Absorbance Liquid Filters as Reference Materials

Optical absorbance liquid filters (OALFs) have been considered as standard reference materials (SRMs) for calibrating spectrophotometers used in clinical chemistry laboratories, often called in vitro diagnostic medical devices (IVD MDs), which mainly use optical absorbance as the basic quantity. Based on an analysis of technical characteristics (working wavelength, photometric range, etc.) of IVD MDs, the main criteria for OALFs were established. Three new types of OALFs that demonstrate good suitability for use as absorbance SRMs for IVD MDs calibration were formulated; they cover 15 of the important wavelengths. Preliminary measurements of the chosen OALFs showed some differences between the instituteś results; agreement of the results is inferior for institutes with less experience. Factors affecting the accuracy and reproducibility will be investigated and taken into account in the next stages of the project.