There are several methods used to lyse cells chemically. Substances such as detergents can be added to cell lysis buffers to solubilize the membrane proteins and puncture the cell membrane to release its contents. Osmotic lysis is another method to lyse cells chemically. The cells are suspended in a hypotonic extracellular environment, which causes the cells to absorb water and burst. Organic solvents such as alcohol or chloroform can disrupt cells by puncturing the cell walls and membranes. EDTA, the chelating agent can be used to disrupt gram negative microorganisms, leaving perforations in the cell walls. Chaotropic agents like urea and guanidine are also used for cell lysis. They bring hydrophobic compounds into aqueous solutions by disrupting the structure of water and making it a less hydrophilic environment.