Exclusion of anchor points in LBA [Bioanalytics]
SDT-01 is anchor and STD-02 is LLOQ of the curve - given a situation
1) when the OD of STD-01 is equal to or greater than that of STD-02 and all standards of the curve meet acceptance criteria, can we choose to mask the lower anchor since we know that the OD is higher.
2) The STD-02 of the curve does not meet criteria and when the lower anchor is masked the same would fall within criteria. in such case can the lower anchor be masked and can this be termed as improvement in curve fit.
3) The method is validated and established with anchors and during routine analysis If the lower anchor is masked for any reason, then since anchor point is included in regression formula for 4 or 5 PL, would the next point i.e. STD-02 (LLOQ) be considered as new anchor and in such case would the curve be accepted.