A chemiluminescence method induced by microplasma jet for nitrites detection and the miniature detection system using smartphone

A method of luminol-diazonium chemiluminescence (CL) induced by microplasma for hazardous substance detection is proposed. The luminol-diazonium CL is caused by microplasma jet, rather than hydrogen peroxide reagent or other oxidizing agents. The CL intensity is increased by the concentration of nitrites. Based on the process of microplasma generation and CL mechanism, the optimal work conditions of the method are obtained. The linear range for nitrites detection is 0.03-1 mmol L-1 with the limit of detection (LOD) of 0.01 mmol L-1. Furthermore, a miniature system using test paper and smartphone is designed for nitrites detection in emergency. The detection system is confined in the custom-tailored shell which is only 28 cm in length, 18 cm in width and 10 cm in height. After microplasma jet treatment, the color of the test paper changes with the NO2-concentration. The photographs of the test paper are taken by the built-in camera of smartphone and analyzed by visiting the website via smartphone. The LOD is 1 mmol L-1 obtained by the CL miniature detection system based on test paper and smartphone. The accuracy, reliability and practicability of the proposed method is verified in this paper.