Analytical Sciences


Abstract − Analytical Sciences, 37(1), 3 (2021).

Inner Product of RGB Unit Vectors for Simple and Versatile Detection of Color Transition
Naoya KAKIUCHI,* Junya OCHIAI,** Masaki TAKEUCHI,*,**,*** and Hideji TANAKA*,**,***
*Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
**Faculty of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
***Institute of Biomedical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
We propose a novel concept for detecting color transition by the inner product (IP) of RGB unit vectors. A digital microscope-based detector and a Visual Basic program were developed in-house. The concept is applied to indicator-based flow titration. The IP is 1 or < 1 if the vector’s direction is the same or different, respectively. The IP’s change can be used as a criterion for the indicator’s color transition. The present IP-based approach is simple, economical, and versatile because it is applicable to any color transition without selecting an analytical wavelength.