Miscible with water, alcohol, ether and benzene.1 Solutions containing even trace levels (nanomolar) of some metal salts (especially copper (II) or cobalt(II)) are unstable at pH > 5 and progressively less stable at higher pH values. Most buffers (especially phosphate) contain enough metal salts to lead to substantial loss of -SH within 1-2 days. The addition of EDTA helps to stabilize solutions. If diluted product needs to be stored it is recommended to store at pH 6-7 with EDTA (0.05 mM) at 2-8°C for no more than 2 to 3 days; however, we highly recommend adding neat 2-mercaptoethanol as needed to the sample.