Natural deep eutectic solvent based ultrasound assisted liquid-liquid micro-extraction method for methyl violet dye determination in contaminated river water

Simple and green natural deep eutectic solvent (NADES) based ultrasound assisted liquid-liquid micro-extraction (UA-LLME) method was developed for extraction and determination of methyl violet dye in contaminated river water samples using UV/Vis spectrophotometry. Choline chloride - decanoic acid based natural deep eutectic solvent was used for extraction. Important analytical parameters like pH, deep eutectic solvent volume/phase ratio, tetrahydrofuran volume, sonication time, and temperature were optimized. Limit of detection (LOD) and limit of quantification (LOQ) were 2.20 & mu;g/L and 7.34 & mu;g/L respectively. Relative standard deviation was 2.35-3.21%. Linearity of method was investigated in a concentration range 10-400 & mu;g/L. Enrichment factor was calculated as 20. For 20 mL sample, the optimized parameters were as deep eutectic solvent volume 1.5 mL, tetrahydrofuran volume was 0.6 mL, pH = 6, sonication time 2 min. The optimized method was tested for extraction of methyl violet in real water samples confirming its applicability in routine environmental analysis.