Supramolecular Solvent-Based Liquid–Liquid Microextraction and Preconcentration of Rhodamine B, Methyl Violet, and Eriochrome Black T in Water, Cosmetics, and Food with Spectrophotometric Quantification

Abstract

Dyes are complex organic compounds that are utilized in many industries. However, excessive exposure to dyes increases susceptibility to various diseases. Their concentrations are below the detection level of many available analytical techniques. Therefore, preconcentration methodology is highly needed prior to their quantification. Herein, a new supramolecular solvent decanol-tetrahydrofuran-based liquid-liquid microextraction method has been established for the first time for the determination of Rhodamine B (Rh B), methyl violet (MV), and Eriochrome black T (EBT) in commercial spices, cosmetics, and water before spectrophotometric quantification. 556, 590, and 530 nm were used for the measurement of Rhodamine B (Rh B), methyl violet (MV), and Eriochrome black T (EBT), respectively. The optimization experiments revealed the best performance at pH 7, 0.9 mL of decanol, 1.3 mL of tetrahydrofuran (THF), and 5 min of vortex time. Under optimized conditions, the limits of detection (LOD) (0.480–0.511 µg L−1), limits of quantification (LOQ) (1.455–1.549 µg L−1), preconcentration factor (PF) (15–20), enhancement factor (EF) (15–20), and relative standard deviation (RSD) (0.5–0.8%) were evaluated. The validation of the method was carried out by standard addition experiments for food, cosmetic, and environmental water samples. The recovery results from 95 ± 6 to 100 ± 4% demonstrate that the method can be successfully applied to practical analysis.