A chemiluminescent method for nitrite detection was developed on microfluidic chip. Carbon dots-NaNO2- acidified H2O2 system was adopted. Chemiluminescence (CL) spectrum of this system was detected. The radiative recombination of hole-injected and electron-injected carbon dots explained their CL property. Spiral microchannels were designed on the microfluidic chip to allow enough reaction time for the carbon dots-NaNO2-acidified H2O2 system. Carbon dots and NaNO2 were premixed in the branch microchannel, then, the mixture reacted with acidified H2O2 in spiral microchannels. Concentrations of H2SO4 and H2O2, dilution ratio of carbon dots in H2O and flow rate were optimized to obtain the best CL signals. The approach presented satisfactory linear relationship between NaNO2 concentration and CL intensity. The tolerance of metal ions in determination of 1 x 10-5M nitrite was analyzed. The nitrites in water and beverage samples were successfully analyzed on the microfluidic chip with good repeatability. The data were well accordance with the results obtained from GB 5009.33- 2010. This microfluidic CL detection method is believed to be a simple, automatic and agent-save approach for inorganic ion analysis.
Wu, Jing, Xiong Wang, Yitong Lin, Yongzan Zheng, Jin-Ming Lin