Simultaneous Preconcentration of Fast Green FCF and Rhodamine B Using Deep Eutectic Solvent and Determination via High-Performance Thin Layer Chromatography

Table 1

Effective factors and limit of levels for response surface quadratic model.

Factor	−α	−1	0	+1	+α
pH	2.10	3.30	4.55	5.70	6.90
Concentration of sodium chloride (mol L^−1)	0.00	0.18	0.35	0.53	0.70
Volume of deep eutectic solvent (μL)	225	300	375	450	525
Stirrer time (min)	5	10	15	20	25