Diclofenac (DCF) is commonly used to relieve the symptoms of many diseases such as rheumatoid arthritis, osteoarthritis, spondylarthritis and ankylosing spondylitis [1, 2] and its global consumption is estimated to be around 940 tons per annum [3, 4] The chemical name is 2-[(2,6-dichlorophenyl)-amino-phenyl]acetic acid (Fig. 1) and it belongs to the class of nonsteroidal anti-inflammatory drugs (NSAIDs), which is commonly used in different dosage and forms such as tablets, ointments or injections .
During the last decade, consumption of pharmaceutical drug products has been increased to extremelevels  and because of their toxicity could pose threats to human health and the ecosystem. NSAIDs can be entered in almost all environmental matrices such as river water, well water, and wastewater, hence resulting in water pollution. The major sources of these water pollutions are the wastewater of pharmaceutical industries, hospital wastes or sewages and domestic wastewater . Several analytical methods have been used to the determination of NSAIDsin plasma and other biological fluids, including voltammetry  capillary electro chromatography(CEC) , micellarelectrokinetic capillary chromatography (MEKC) , chemiluminescence , capillary electrophoresis , chromatography  and potentiometry .
In recent years, magnetic solid-phase extraction (MSPE), as a novel SPE method, has been used as a sorbent from magnetic nanoparticles (MNPs) and thus most important steps in chemical analysis have been revolted, including sample preparation and pre-concentration procedures[15, 16]. Main advantages of the Nano-sized materials in comparison to different types of sorbents in SPE method are high specific surface areas, rapid adsorption rate, highly active surface sites, inexpensive, short equilibrium time, being automatic, controllability and separating them by applying an appropriate magnetic field, non-toxicity and reusability [17–23].
In SPE, optimization of extraction condition (volume sample, sample ionic strength, pH, amount of surfactant, a dose of sorbent, desorption and extraction time) is more important. Optimized procedures are usually carried out with a univariate method which means one factor at a time (OFAT). Besides being time-consuming and laboring, OFAT methods do not involve an interaction between factors. Chemometric calculations are cost-effective, useful, practical and efficient statistical approaches that can use for screening optimization of analytical procedures. These methods provide several advantages such as the reagent consumption and analysis time reduction. The most relevant multivariate techniques used in analytical optimization is response surface methodology (RSM) that is based on Plackett-Burman Design (PBD), Central Composite Design (CCD) and Design of Experiment (DOE). It can be used for calculation of affective factors simultaneously more accurate combination and evaluation in permit assessment [24, 25].
In this research, MSPE was used as a sample preparation method for separation and preconcentration of DCF which was finally analyzed by UV-Vis spectrophotometer using RSM and employing a CCD Experimental method. In order to improve the sorption capacity and selectivity of nanocomposite for DCF, L-arginine amino acid (L-Arg) was coated on the surface of magnetic dialdehyde starch (MDAS) nanocomposite and sorbent extractability of DCF was examined. In addition, seven important factors including sample volume, salt effect, pH, amount of surfactant and sorbent, desorption and extraction time were selected to optimize.