10X Phosphate-buffered Saline (PBS) is ideal for use in sample preparation and as a wash bufferÂ in general immunoassay applications as well as tissue and cell culture procedures. This modified Dulbecco's buffer is not formulated with magnesium or calcium salts. Tween 20, a non-ionic detergent, reduces non-specific binding and protein-protein interaction during the wash step in immunoassay procedures. pH=7.4. Conductivity controlled.