Application of the glass slab optical waveguide to the spectrophotometric determination of the iron (II)—1, 10-phenanthroline complex by flow analysis

A slab optical waveguide (SOWG) absorption detector was applied to the determination of the orange-red Fe(II)—1,10-pheranthroline complex [Fe(phen)3]2+ by flow analysis. When a sample solution containing [Fe(phen)3]2+ was introduced into a flow of sodium dodecylbenzene sulphate (DBS−) solution, an ion pair of [Fe(phen)3]2+ and DBS− was formed in a mixing coil, and was then adsorbed on the glass SOWG. The adsorbed ion pair caused the attenuation of light of a green He-Ne laser(543.5 nm) or of an Ar ion laser (multi-line, mainly 488 nm and 515 nm). The best sensitivity was obtained with a glass SOWG fabricated by a radio frequency sputtering method, which was 9.5 times higher than that with a conventional spectrophotometer (1-cm cell) for a 0.5-ml sample solution.