|  |
Program |
 |
| |
 |
General Session 4: Marine environment, ecosystem & sustainability |
| |
|
|
An In-situ colorimetric optical imaging sensor with diffusive gradient in thin-film for determination of dissolved Fe(II) in pore and bottom waters
GS4-09-S
Chengrong Guo* , State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
Mingjie Ma, State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
Dongxing Yuan, State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
Sichao Feng, State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
Kunning Lin, State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen, China
Presenter Email: 33120151152486@stu.xmu.edu.cn
|
| Background: Iron (Fe) is one of the most important trace metals in various biogeochemical reactions and processes. As a key iron species in marine water system, dissolved Fe(II) draws much attention. In-situ detection technique for dissolved Fe(II) in pore and bottom waters is highly desired, for its free of transformation and contamination during difficult sampling and longtime sample transportation. Goal and Principle: This study targets to develop a novel optical sensor combining diffusive gradients in thin-film (DGT) and colorimetric optical imaging device for in-situ determination of dissolved Fe(II) in pore and bottom waters. DGT also served as a preconcentration film, and the reagent binding on the DGT formed color complex with Fe(II), which was imaged with an underwater camera and analyzed with a commercial software. Method: The DGT binding layer was based on polyacrylamide gel and impregnated with C18 and covalently immobilized with Ferrozine (3-(2-pyridyl)-5,6-diphenyl- 1,2,4-trizine-p,p'-disulfonic acid monosodium salt hydrate). When dissolved Fe(II) was diffusing through polyacrylamide gel, it reacted with Ferrozine to form a magenta color complex compound, which could be recorded in-situ by an underwater camera, together with a standard Fe(II) complex film. The colorimetry through the grey of both sample and standard images was analyzed with software Image-J. The final quantization analysis of Fe(II) was done with DGT deploying time and the diffusion coefficient. Experiments: A cylinder-type housing was built to hold the DGT device and underwater camera. Formula of polyacrylamide gel and concentrations of C18 and Ferrozine in the binding gel were optimized. Diffusion coefficient of dissolved Fe(II) in DGT was determined. Reproducibility, recovery and detection limit have been tested. Application: The sensor system was deployed in lake and estuary sediment, and dissolved Fe(II) in pore and/or bottom waters was analyzed. The analytical results obtained with the proposed sensor and AAS were compared. Perspective: The improved sensor system can be applied in deep sea by ROV for hours or days, accumulation of dissolved Fe(II) on the DGT can be recorded at real time and the concentration of dissolved Fe(II) in bottom seawater can be in-situ measured. |
|
|
|
|