– Rhodamine B hydrazide serves as an effective probe for sulfite detection, transitioning from colorless and non-fluorescent to emitting Rhodamine B-like fluorescence upon interaction with sulfite (5-800 ng/mL; detection limit=1.4 ng/mL (3σ)). This process occurs as sulfite reduces dissolved oxygen, generating superoxide radicals that react with Rhodamine B hydrazide to yield Rhodamine B. The addition of Tween 80 surfactant micelles further enhances this fluorescence. The absorption and fluorescence emission maxima of Rhodamine B hydrazide are at 554 nm and 574 nm, respectively [1].