Determination of sulphide in blood with an ion-selective electrode by pre-concentration of trapped sulphide in sodium hydroxide solution

Abstract

A method for the determination of sulphide in blood using an ion-selective electrode and a wash-bottle reactor has been developed. The method involves liberation of blood sulphide by addition of acid and subsequent trapping of the liberated H₂S gas in NaOH solution. The H₂S is determined directly with the ion-selective electrode and without any interference from other blood components. This method is ten times more sensitive than the conventional Conway microdiffusion determination and a sulphide detection limit of approximately 3 × 10^–7M(10 µg l^–1) can be achieved. Blood sulphide concentrations in 12 non-fatal cases of acute hydrogen sulphide poisoning ranged from 1.3 × 10^–6 to 18.8 × 10^–6M(40–600 µg l^–1).