37.2.2. Freelite and Hevylite Precision on the Optilite
Precision on the Optilite is very good due to the use of disposable cuvettes and stringent washing protocols for the sample probe, reagent probe and mixing paddle. During Freelite assay validation, assay precision was assessed using 3 control fluids that ranged in concentration from 4.7 mg/L to 71.8 mg/L. The maximum intra- and inter-assay imprecision for κor λ Freelite assays was 3.3% and 3.2%, respectively. Similar studies of Hevylite reagents utilising control fluids that varied from 0.26 g/L IgAκ to 25.18 g/L IgGκ demonstrated a maximum intra- and inter-assay imprecision for 6 Hevylite assays of 3.2% and 4.7%, respectively.
Thouless et al. reported excellent inter-assay precision for Freelite Optilite assays under routine simulated conditions, with a maximum imprecision of 7.0%. This was supported by Leung et al. who reported CVs of <8% at every level for multiple serum assays (including Freelite) run on the Optilite in routine practice. A number of studies have reported very good Hevylite Optilite assay precision with typical CVs of 3-8%.
Jamil et al. assessed the performance of the Freelite Mx kits for CSF analysis (Chapter 36) and reported that the assays were linear, with acceptable CVs, and produced results that compared well to those generated by the predicate method.