The present invention relates to a method for determining the presence, absence or amount of biologically active HGF in a sample, comprising the steps (i) bringing the sample in contact with a first porous solid phase comprising a HGF binding component of the extracellular matrix or cell membrane, and an indicator composition comprising bromothymol blue and a quaternary ammonium compound; and (ii) correlating the color of the porous solid phase with the presence, absence or amount of biologically active HGF in the sample. It further relates to a device comprising a first porous solid phase comprising at least one HGF-binding component of the extracellular matrix or cell membrane, and an indicator composition comprising bromothymol blue and a quaternary ammonium compound.