“…In several FIA systems based on optode detectors, the onechannel FIA system, in which a sample solution is introduced into a flow of a regeneration solution (RS), is used. [21][22][23][24][25][26][27][28] Here, the more standard two-channel FIA system is adopted. Figure 1 depicts the two-channel FIA system, which is made up of two syringe pumps (YSP-101, YMC, Kyoto, Japan), a sample injector, a homemade optode detector, a light source (a tungstenhalogen lamp, LS-1, Ocean Optics, USA), and a fiber-optic spectrophotometer (USB 4000, Ocean Optics, USA) connected to a personal computer (PC).…”