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Extraction, preconcentration, and determination of methylphenidate in urine sample using solvent bar microextraction in combination with HPLC–UV: Optimization by experimental design

ABSTRACT Methylphenidate (Ritalin) is a drug used for attention-deficit hyperactivity disorder treatment and narcolepsy symptoms control. This drug inhibits norepinephrine and dopamine reuptake in presynaptic neuron and appears to stimulate the cerebral cortex and subcortical structures similar to amphetamines. The aim of this work is to develop a new method for extraction, preconcentration, and determination of methylphenidate in human urine samples using solvent bar microextraction combined with HPLC and optimization by design of experiment approach. To get to the highest preconcentration factor, the effect of various affecting parameters such as the type of extraction solvent, donor phase pH, receiving phase pH, salt addition to the acceptor phase, extraction time, stirring speed, and extraction temperature was investigated and optimized by design of experiment approach. Under the optimized condition extraction (solvent: n-octanol, donor phase pH: 11.6; acceptor phase pH: 4; stirring speed: 650 rpm; extraction time: 25 min; temperature: 25°C; salt concentration in donor phase: 30% w/v NaCl), the following results were achieved: preconcentration factor: 104, limit of detection: 15 ng/mL, intra-day RSD: 3.5%, and inter-day RSD: 3.9%. Finally, the feasibility of this extraction method was confirmed by analyzing urine sample and satisfactory results were obtained. GRAPHICAL ABSTRACT