title: Ascorbic acid surface modified TiO₂-thin layers as a fully integrated analysis system for visual simultaneous detection of organophosphorus pesticides.
abstract: TiO₂ photocatalysis and colorimetric detection are coupled with thin layer chromatography (TLC) for the first time to develop a fully integrated analysis system. Titania@polystyrene hybrid microspheres were surface modified with ascorbic acid, denoted AA-TiO₂@PS, and used as the stationary phase for TLC. Because the affinity between AA-TiO₂@PS and organophosphorus pesticides (OPs) was different for different species of OPs (including chlopyrifos, malathion, parathion, parathion-methyl, and methamidophos), OPs could be separated simultaneously by the mobile phase in 12.0 min with different Rf values. After surface modification, the UV-vis wavelength response range of AA-TiO₂@PS was expanded to 650 nm. Under visible-light irradiation, all of the OPs could be photodegraded to PO₄(3-) in 25.0 min. Based on the chromogenic reaction between PO₄(3-) and chromogenic agents (ammonium molybdate and ascorbic acid), OPs were quantified from color intensity images using a scanner in conjunction with image processing software. So, AA-TiO₂@PS was respectively used as the stationary phase of TLC for efficient separation of OPs, as a photocatalyst for species transformation of phosphorus, and as a colorimetric probe for on-field simultaneous visual detection of OPs in natural water. Linear calibration curves for each OP ranged from 19.3 nmol P L(-1) to 2.30 μmol P L(-1). This integrated analysis system was simple, inexpensive, easy to operate, and sensitive.
authors.affiliation: Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Zhangzhou, 363000, China.
authors.forename: Shunxing
authors.initials: S
authors.lastname: Li
authors.forename: Wenjie
authors.initials: W
authors.lastname: Liang
authors.forename: Fengying
authors.initials: F
authors.lastname: Zheng
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Lin
authors.forename: Jiabai
authors.initials: J
authors.lastname: Cai
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry*; D002384:Catalysis; D002855:Chromatography, Thin Layer / Q000379:methods; D003124:Colorimetry / Q000379:methods; D009943:Organophosphorus Compounds / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry*
chemical_list: D009943:Organophosphorus Compounds; D010575:Pesticides; C009495:titanium dioxide; D014025:Titanium; D001205:Ascorbic Acid