Chiral Optical Sensing of Amino Acids with 2-Trifluoromethyl Benzaldehyde for <i>Ophiopogon japonicus</i> Authentication

The detection and analysis of chiral molecules have long been challenging in analytical chemistry. This study introduces a novel approach that utilizes 2-trifluoromethyl benzaldehyde as a small-molecule probe capable of forming a stable Schiff base with chiral amino acids in aqueous solution under alkaline conditions. The amino acid Schiff bases present a strong Cotton effect and UV absorption at wavelengths exceeding 260 nm, enabling chiral analysis, including assignment of absolute configuration, enantiomeric composition, and total concentration. An application of this method was the authentication of the herbal medicine <i>Ophiopogon japonicus</i>. Using principal component analysis and orthogonal partial least squares discriminant analysis, we successfully differentiated <i>O. japonicus</i> samples collected in two distinct locations with 20 samples. This rapid and convenient method offers a new approach to quality control of herbal medicine.