Method verification of reagent with elevated biotin interference threshold for interleukin-6 on Cobas e601 with evaluation of sample storage duration.

Ensuring correct analytical responses is of the utmost importance in laboratory workand interferences with analyses can give incorrect results. Work to improve the precision of the analyses is an ongoing process. An interference in the analysis of Interleukin-6 (IL-6), a cytokine that reflects inflammatory processes in the body, is biotin. Biotin interferes with EnzymeLinkedImmunoSorbentAssay (ELISA) analysis by binding in to streptavidin thereby causing falsely low analytical responses. An attempt to reduce that interference is to raise the threshold for biotin by introducing a new reagent. The aim of this project was to introduce a new reagent with elevated biotin interference threshold and carry out a precision measurement as well as a patient comparison. In addition, a sustainability study was carried out to investigate possible changes in IL-6 concentration when samples are stored in room temperature with open or closed vessels. Control material was analysed during three consecutive days. The patient comparison was performed by analysing 20 patient samples with both the older reagent and the new one. The sustainability study was preformed last and here were 7 patient samples used to perform this part of the study. The control material was analysed with good results, a total coefficient of variation (CV%) was calculated at 1.6% for the lower control and 3.0% for the higher one. The comparison showed good correlation with only a minor negative bias for the new reagent. The sustainability study showed, in line with what the supplier has indicated, a sample shelf life of 6 h at room temperature without sealing. Interesting to mention is that samples over 50 pg/mL showed a shelf life more than 24 h at room temperature without sealing. The decision was made by the medically responsible doctor that the reagent was approved for use in the laboratory