Load 22.5µl water and 2.5µl sample into 96 well plate. Test each sample in triplicate.
Load standard (e.g., 1µl, 2µl, 5µl, 10µl, 20µl and 25µl of 1µg/µl BSA standard and add water to 25µl total volume for each - perform in duplicate)
Mix BCA reagents (reagent A and reagent B) make enough for all your samples plus some extra so that you don't run out.
Add 200µl of BCA reagents to each sample and standard. Let incubate 15-30min at 37C.
Read absorbance at OD540.
Plot standard curve using BSA standard. Use equation from graph to determine concentration (µg/µl) of samples.