title: Fluorescence ratiometric pH sensor prepared from covalently immobilized porphyrin and benzothioxanthene.
abstract: A fluorescence ratiometric sensor for pH determination is described in this paper. The sensor incorporated the pH-sensitive dye meso-5,10,15,20-tetra-(4-allyloxyphenyl)porphyrin (TAPP) as an indicator and a pH-insensitive dye N-(2-methacryloxyethyl)benzo[k,l]thioxanthene-3,4-dicarboximide (MBTD), a benzothioxanthene derivative, as a reference for fluorescence ratiometric measurement. To prevent leakage of the dyes, both were photocopolymerized with acrylamide, hydroxyethyl methacrylate, and triethylene glycol dimethacrylate on the silanized glass surface. The reproducibility and response time of the prepared sensor were sufficient. Most common coexisting inorganic ions and organic compounds did not interfere with pH sensing. In the acidic pH range from 1.5 to 5.0 the fluorescence intensity ratio of the two dyes varied linearly as a function of pH. The sensing membrane was found to have a lifetime of at least one month. The sensor was applied to the analysis of waste water and artificial samples.
authors.affiliation: Department of Environmental Science and Engineering, State Key Laboratory for Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, PR China. cgniu@hnu.cn
authors.forename: Cheng-Gang
authors.initials: CG
authors.lastname: Niu
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Gui
authors.forename: Guang-Ming
authors.initials: GM
authors.lastname: Zeng
authors.forename: Ai-Ling
authors.initials: AL
authors.lastname: Guan
authors.forename: Pan-Feng
authors.initials: PF
authors.lastname: Gao
authors.forename: Pin-Zhu
authors.initials: PZ
authors.lastname: Qin
mesh_terms: D020106:Acrylamide / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry*; D005470:Fluorometry / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007287:Inorganic Chemicals / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry; D010777:Photochemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D015203:Reproducibility of Results; D012821:Silanes / Q000737:chemistry; D013892:Thioxanthenes / Q000737:chemistry*; D014873:Water Pollutants / Q000032:analysis
chemical_list: D005456:Fluorescent Dyes; D007287:Inorganic Chemicals; D008689:Methacrylates; D009930:Organic Chemicals; D011109:Polymethacrylic Acids; D011166:Porphyrins; D012821:Silanes; D013892:Thioxanthenes; D014873:Water Pollutants; C020946:triethylene glycol dimethacrylate; D020106:Acrylamide; D011092:Polyethylene Glycols; C005044:hydroxyethyl methacrylate