Acid-free synthesis of S-nitrosothiols at neutral pH by shock-freezing in liquid nitrogen

A laboratory method for the acid-free synthesis of S -nitrosothiols (RSNO) from NaNO2 and thiols in aqueous buffer of neutral pH is reported. Equimolar amounts of NaNO2 and thiol are added to a 100- µM Na 4 EDTA-containing Na2HPO4 buffer (100 mM, pH 7.4). Samples are set into liquid nitrogen for 1 min and then thawed to room temperature or in an ice bath. Dependent upon the RSNO, repetition of the procedure may be required. This method may be of particular importance when the classical acid-based method fails or releases harmful gases such as H2S.