Highly Accurate Fluoride ion Detection in Tap Water with Diluted Buffer Solution

Abstract

Polycrystalline (poly) lanthanum fluoride (LaF 3 ) Electrolyte Insulator Semiconductor (EIS) sensors can serve as a promising portable sensor platform for monitoring fluoride ion (F −−) concentration due to small size, fast response and simple fabrication method. The key successful implementation is to consider and understand the effects of measurement environments on the F detection. Here, we propose a pathway for accurate F analysi s in tap water by using low concentration of buffer solution. The F sensing characteristics of poly LaF 3 EIS sensors are extensively investigated by varying the concentration of total ionic strength adjustment buffer solution (TISAB). The sensors exhibit a high sensitivity ( S pF ) of 50.3 mV/pF, a low limit of detection (LOD) of 1.4 ppb in the 100 times diluted TISAB (0.01×TISAB). In addition, the poly LaF 3 EIS sensor shows a good selective detection of F over other ions. When F analysis of tap water is compared to a commercial F ion selective electrode, the results is only different by 6.1 % for the 0.01×TISAB compared to 11.2 % for 1×TISAB. Thus, the dilution of TISAB can provide better measurement condition for highly accurate F analysis in actual sens or applications.