A new dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLMESFO)/
flow injection-spectrophotometry (FI) method for simultaneous separation and preconcentration of trace amounts of
copper and zinc was developed. 1-(2-pyridylazo)-2-naphthol (PAN), 1-undecanol and acetonitrile were used as chelating
agent, extraction solvent and disperser solvent, respectively. The factors influencing the complex formation and extraction
by DLLME-SFO such as volumes of extraction and disperser solvents, pH, concentration of salt and concentration of the
chelating agent were optimized. The optimal conditions were: volumes of extraction and dispersive solvents, 80 and 200
μL, respectively; concentration of the complexing agent, 4 x10x3mol L-1 and pH,7.5. Partial least squares (PLS) were applied
for multivariate calibration and noise reduction by eliminating less important latent variables. The data obtained
from the experiments were processed by chemometrics method of PLS. The linear dynamic range for Cu2+ and Zn2+ was
3–30 μg L-1 and 1–23 μg L-1, respectively. Detection limits were 1.5 μg L-1 and 0.25 μg L-1 for Cu and Zn, respectively.
The relative standard deviations (R.S.D., n = 10) were found to be less than 4.5% for both of metal ions. The method was
successfully applied to the simultaneous determination of Cu and Zn in the real water samples and satisfactory relative recoveries
(92–107.5%) were achieved. The enhancement factors for Cu2+ and Zn2+ were found to be 85 and 86.3, respectively.
Keywords: Copper and zinc, DLLME-SFO, PLS, simultaneous determination, concentration, disperser solvent, chemometrics method, dispersive liquid–liquid microextraction , SFODME
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