The determination of glutathione in the presence of nitrite.

Studies on the possible r&e of reduced glutathione (GSH) in the conversion of the drugs nitroglycerin and erythritol tetranitrate to nitrites (1) and in the reduction of methemoglobin to hemoglobin (2) have led to the need for a method of determining GSH in the presence of nitrite. The common methods for GSH cannot be employed for this purpose because nitrite interferes with the analyses. This has been found to be true of the iodometric and the nitroprusside procedures for GSH, and the amperometric titration method for sulfhydryl groups. Heppel and Hilmoe (1) were able to decrease the interference of nitrite in the iodometric procedure by the addition of sulfanilamide, but recoveries were only 72 per cent or less. The present paper describes simple modifications of the nitroprusside method of Grunert and Phillips (3) and the amperometric procedure of Benesch and Benesch (4) in which sulfamic acid is used to remove nitrite and thus eliminate its interference. Good recoveries have been achieved.