Environmentally friendly liquid medium for a cost-effective long-path absorption liquid core waveguide with a gas diffusion flow analysis system

Abstract

An environmentally friendly modified flow analysis carrier with a high refractive index liquid to perform a total internal refrection phenomenon in a typical Teflon tube was achieved as a cost-effective long-path liquid core waveguide (LCW) for absorption spectrophotometry. A home-built LED-photodiode based long-path colorimeter was demonstrated to enhance the sensitivity of chemical analysis without using a preconcentration unit. A low toxicity carrier such as syrup or ethanol was selected to improve the sensitivity for NH4+ ion determination via butterfly pea flower extract reagent in a gas-diffusion flow injection (GD-FI) system. A linear calibration range of NH4+ ion determination in the GD-FI based on syrup modified LCW (mLCW) system of 10–500 µmol L−1 can be obtained with a detection limit of 9.8 µmol L−1, repeatability of <2% RSD, and 12 injections h−1 sample throughput. The proposed cost-effective and environmentally friendly mLCW shows the potential to apply with other natural/synthetic chromogenic reagents for the green chemical analysis approach.