| | Re: Higher Titers on outside rows
assuming that you are sealing your plate during the incubations, edge effects are usually caused by a temperature gradient during one or more incubation steps.
so, for example, addition of cold substrate to a plate at room temp, will result in the edge wells warming more rapidly than those in the centre, so the reaction progresses more rapidly on the periphery.
The same effect will be seen for binding of a detection antibody (and I have seen antigen down overnight assay coating steps dramatically affected by the same thing)
Solution is to ensure that all the reagents are at the incubation temperature before they are added to the plate, and if you want to go the extra mile, ensure that the plate and wash buffers are also at the incubation temperature.
Perform a uniformity assessment, by plating the same thing in all 96 wells at mid curve concentration, and aim for response CVs in the 5 to 7% range and no evidence of edge effects for a robust assay.
Other things that can cause drift, rather than edge effects, include differential plate drying between plate washing and solution application. Lab humidity variations can dramatically influence this problem. I always ensure that the well is wet, by minimizing interval between washing and application of subsequent solution (30 seconds or less) and always use a 96 well polypropylene preload plate and a multichannel pipette to load samples to empty wells.