In situ Determination of Phenanthrene Adsorbed onto Surface of Mangrove Leaves Using a Laser-Induced Nanosecond Time-Resolved Fluorescence System

To further achieve the field detection of PAHs in actual leaf samples, it is important to develop novel methods for in situ determination of polycyclic aromatic hydrocarbons (PAHs) in plant leaves. Normally, phenanthrene (Phe) is adsorbed onto the leaf surfaces of three kinds of mangrove species, named Kandelia obovata (Ko), Bruguiera gymnorhiza (Bg) and Aegiceras corniculatum (Ac). A set of laser-induced nanosecond time-resolved fluorescence (LITRF) system was utilized for the in situ quantitative detection of the absorbed phenanthrene (Phe) Experimental results showed that the linear dynamic ranges for the in situ determination of the Phe adsorbed onto the leaf surfaces of Ko, Bg and Ac were 2–1400 ng/spot, 1–1000 ng/spot and 4–2000 ng/spot, with the detection limits of 0.20, 0.14 and 0.42 ng/spot, respectively. The relative standard deviations were less than 6.0% (n = 9). The experimental recoveries for the Ko, Bg, and Ac were 89.6%–108.1%, 78.2%–92.4% and 93.2%–112.9%, respectively. Satisfactory results were obtained for the in situ determination of the Phe adsorbed onto the surfaces of the lab-exposure mangrove leaf samples contaminated by the Phe. The sensitivity of the established method was much higher than that of the previously established fiber optical fluorimetry, and the linear dynamic range got improved. The LITRF method marked a significant step towards to realizing the field detection of PAHs adsorbed onto the mangrove leaves.

This figure shows the fluorescence emission spectra of phenanthrene adsorbed onto the leaf surfaces of Bruguiera gymnorhiza. It can be seen that the autofluorescence of the uncontaminated leaves did not interfere with the determination of phenanthrene, and the fluorescence intensity increased with the increasing of the concentration of the adsorbed phenanthrene.Figure optionsDownload as PowerPoint slide