Central Composite Design Applied to Optimization of Dispersive Liquid–Liquid Microextraction of Cu(II) and Zn(II) in Water Followed by High Performance Liquid Chromatography Determination

Abstract

In this study a new method for the simultaneous determination of Cu(II) and Zn(II) ions in water samples was developed by dispersive liquid-liquid microextraction preconcentration followed by HPLC with UV detection. An experimental design, central composite design, coupled with response-surface methodology was used for the optimization of the involved experimental parameters. In the proposed approach, 8-hydroxy quinoline (HOX) was used as a chelating agent and chloroform and methanol were chosen as the best extraction and dispersive solvents, respectively. Some factors influencing the extraction efficiency of copper and zinc ions and their subsequent determinations, including extraction and dispersive solvents kinds and volumes, pH of sample solution, concentration of the chelating agent, salting out effect and reaction time were studied and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 10-4000 mg/L with the detection limits of 3 mg/L and the quantification limits of 10 mg/L for both analytes. The RSD for six replicate measurements of 500 mg/L of Cu 2þ and Zn 2þ were 2.9% and 5.7%, respectively.

Ionic liquid-modified Fe3O4 nanoparticle combined with central composite design for rapid preconcentration and determination of palladium ions

“…A fairly high R 2 predicted value of 0.7272 implies that the regression model was statistically significant. As mentioned, R 2 , R 2 adjusted, and R 2 predicted can be used to evaluate model fitness, and in a good model these parameters should not be too different from each other [37]. Based on p-values of each model term, all the independent variables studied (A, B, C, D) and four quadratic terms (A 2 , B 2 , C 2 , and D 2 ) significantly affected the preconcentration of Pd(II).…”

Microextração Líquido-Líquido Dispersiva (DLLME): Fundamentos e aplicações

“…Os estudos relatam que o uso do ultrassom aumenta a eficiência gando o método QuEChERS, ou, no caso de metais, a mineralização [36] . Neste caso, a DLLME é utilizada para concentrar os extratos.…”

A New Dispersive Liquid–Liquid Microextraction Method for Preconcentration of Copper from Waters and Cereal Flours and Determination by Flame Atomic Absorption Spectrometry

“…The analytes are concentrated into the fine droplets of the extraction solvent which are further separated by centrifugation and used for the instrumental determination of the analyte. The advantages of the DLLME method are simplicity of operation, rapidity, low cost, high recovery, and enrichment factors (Farajzadeh et al 2010;Baliza et al 2009). …”

“…Several analytical techniques, including electrothermal atomic absorption spectrometry (ETAAS) (Stanisz and Zgoła-Grzeskowiak 2013;Chen et al 2009), X-ray fluorescence spectrometry (XRF) (Kocot et al 2012), high performance liquid chromatography (HPLC) (Farajzadeh et al 2010), inductively coupled plasmaoptical emission spectrometry (ICP-OES) (Otero- Romani et al 2005;Zhao et al 2012), inductively coupled plasma-mass spectrometry (ICP-MS) (Trujillo et al 2012), flame atomic absorption spectrometry (FAAS) (Shrivas and Jaiswal 2013;Imamoglu and Tekir 2008;Karadaş and Kara 2013), voltammetry (Kumar et al 2005), and spectrophotometry (Gouda and Amin 2014;Rumori and Cerda 2003) have been reported for the determination of copper in various types of sample. Flame atomic absorption spectrometry (FAAS) is a relatively simple and readily available analytical instrument in many laboratories.…”

“…However, most of the methods have some disadvantages, such as being time consuming, producing unsatisfactory enrichment factors, using significant chemical additives, using large quantities of organic solvents, producing large volumes of secondary wastes and the requirement of complex equipment. In order to remove these disadvantages, several liquid-liquid microextraction techniques were developed such as cloud point extraction (CPE) (Gouda and Amin 2014;Zhao et al 2012), single drop microextraction (SDME) (Wen et al 2011), solidified floating organic drop microextraction (SFODME) (Şahin and Tokgöz 2010;Durukan et al 2011), homogeneous liquid-liquid extraction (HLLE) (Jamali et al 2007;Farajzadeh et al 2009), and dispersive liquid-liquid microextraction (DLLME) (Kandhro et al 2014;Kocot et al 2012;Farajzadeh et al 2010;Shrivas and Jaiswal 2013).…”