Distinguishing endogenous and exogenous sulfide by mass spectroscopy

Abstract

Hydrogen sulfide exhibits many characteristics of an endogenous biological mediator and is present at low baseline levels in tissues and blood. A large body of evidence suggests that exogenously applied sulfide may also be suitable as a therapeutic agent. Therefore, a method using the rare 34S sulfur isotope was developed and validated to distinguish exogenously administered sulfide from endogenous sulfide which is predominantly 32S‐sulfide. Sodium 34S‐sulfide was prepared and administered intravenously to Sprague Dawley rats. Concentrations of 32S and 34S‐sulfide were measured in blood and tissues after derivatization with monobromobimane as monobromobimane derivative, separation by reverse phase HPLC and quantification by mass spectroscopy. On intravenous infusion of sodium 34S‐sulfide into rats, blood sulfide concentrations of 34S‐sulfide, but not 32S‐sulfide increased in a dose‐dependent manner indicating that exogenously administered sulfide can be traced and distinguished from endogenous sulfide. The method will be useful in monitoring of the distribution of therapeutic sulfide in tissues and organs.