A novel propylene glycol alginate gel based colorimetric tube for rapid detection of nitrite in pickled vegetables.

The detection of nitrite is of great significance because it is closely related to food safety. In this work, a rapid colorimetric method was developed for nitrite detection based on the reaction of propylene glycol alginate (PGA) gel interface. In the reaction of nitrite and 4-Aminoacetophenone, diazo compound formed, which could be further transformed to purplish red compound by reacting with N-(1-Naphthyl)ethylenediamine (NED). Nitrite exhibited a linear relationship with the grayscale of the gel interface in the range of 0.3-9 μg mL-1 with a detection limit of 0.3 μg mL-1. The method was applied to detect nitrite in four types of pickled vegetables with recovery of 80.9-119.02% and relative standard deviation of 0.11-6.73%. Notably, the detection process can be accomplished within 5 min. The proposed colorimetric method exhibited advantages of simplicity, quickness and sensitivity, showing potential application prospects for the real-time and on-site detection of nitrite in pickled vegetables.