Development and Initial Calibration of a Portable Laser-Induced Fluorescence System Used for In Situ Measurements of Trace Plastics and Dissolved Organic Compounds in Seawater and the Gulf of Mexico

A portable UV laser-induced fluorescence system that uses a high pulsed repetition frequency (8-kHz) microchip laser at 266 nm, 13 switchable optical filters, and a gated photomultiplier tube detector has been developed and tested successfully for the detection of leached plastics (possibly bisphenol-A) and trace dissolved organic compounds in seawater. The instrument is 100 times more sensitive than commercial portable spectrofluorometers and measures a complete fluorescence spectrum in a moderate time period of 1-2 min. The system was tested in the Gulf of Mexico over varying water masses. In addition, fluorescence lifetime, bleaching, and temporal flow characteristics were studied.