Reconstitute in an equivalent volume to the weight you purchased, so that the final concentration is 1 mg/ml. For example, if you purchased 100 µg of antibody, resuspend in 100 µl of pure distilled water. Dissolve the entire contents in water by mixing and lightly centrifuging at room temperature. It is possible to dissolve the contents in larger volume (200-500 µl) but the subsequent dilution may have to be adjusted. Insoluble lipoproteins may aggregate on storage. These do not interfere with the solubility of the antibody, spin down and use the clear supernatant.