Online ultrasonic nebulizer assisted laser induced breakdown spectroscopy (OUN-LIBS): An online metal elements sensor for marine water analysis

Abstract

Metal element detection technologies for seawater analysis are very important in the fields of marine scientific investigation and environmental monitoring. The current technologies cannot meet the requirements of detection capabilities, such as online, real-time, multi-element and highly sensitive while used in the above fields on-site. A newly developed sensor named online ultrasonic nebulizer assisted laser induced breakdown spectroscopy (OUN-LIBS) is introduced in this paper which is expected to be used for on-site seawater analysis. The core design idea of this sensor is to combine an online ultrasonic nebulizing auxiliary device with a traditional LIBS system to nebulize the liquid samples into aerosol for LIBS detection in order to realize a continuously, highly sensitive, stable and fast on-site detection. Based on this idea, a hardware system composed of an adapter module, a nebulizing module and an optical module and a software system with communication, control and display functions were designed. The laboratory experiments and marine field testing were carried out to assess the sensor. Under the status of continuous online detection, the LODs of the 6 target elements are lower than 1 ppm and the stability of spectral line intensity of Ca is lower than 0.38%. Besides the traditional calibration curve method, an online and on-site standard sample calibration method is adopted in the concentration quantitative analysis. The results of research show that the accuracy of online quantification analysis is very impressive even in the marine field testing.