Combination of Dispersive Liquid-Liquid Micro-Extraction by HPLC-UV and Response Surface Methodology to Optimize Determination of Ciprofloxacin in Infant Formula

A rapid, efficient, and environmentally friendly extraction method, namely dispersive liquid-liquid micro-extraction (DLLME) coupled with high performance liquid chromatography (HPLC), was applied for extraction of ciprofloxacin from infant formula. In this method, chloroform and acetone were used as the extracting and dispersing solvents, followed by HPLC analytical method. Using DLLME, ciprofloxacin contained in infant formula, was extracted and concentrated into the organic phase. Hence several parameters, such as type and volume of extraction and dispersive solvents, pH, salt addition, and extraction time, affect the DLLME extraction procedure efficiency, an optimization approach was used to attain the best extraction conditions [1]. Accordingly, initial screenings were first investigated by one factor at the time approach. Further optimization with Box-Behnken and response surface methodology showed that, pH, and volumes of extraction and dispersive solvents were effective variables, respectively [2, 3]. By fitting a second-order polynomial model to the experimental data, the optimum conditions for pH, volumes of extraction and dispersive solvents were found to be 4.25, 550μL and 760μL, respectively. The perfect agreement between the observed values and values predicted by the model were obtained in the light of Design of Experiment (DoE). Therefore, under optimized experimental status of DLLME-HPLC-UV method, a good linearity in the range of 50 – 1000 μg L−1, detection limits of (10 μg L−1), and recovery of 87% were obtained. In addition, considering the obtained figures of merit, the method proved to be reliable, precise and accurate. In fact, the method was successfully applied to determine ciprofloxacin in infant formula.