Vortex assisted switchable-hydrophilicity solvent based homogeneous liquid-liquid micro extraction for the determination of methadone in urine and plasma samples prior to GC-FID

Vortex assisted homogeneous liquid-liquid microextraction based on switchable-hydrophilicity solvent coupled to GC-FID (VA-HLLM-SHS) has been applied for preconcentration and separation of methadone in the biological samples. The water: amine volume ratio allowed triethylamine (TEA) to act as a switchable-hydrophilicity solvent. The switching process was carried out in the presence of carbon dioxide (CO2) as the trigger due to low cost, non-toxicity and easy of removing of CO2. The vortex was introduced to form fine droplets of the extractant into the aqueous solution, and enlarge the contact surface between both immiscible liquids. Methadone was extracted into triethylamine. Separation of two phases was carried out by the addition of sodium hydroxide, which changed the ionization state of triethylamine. Some important parameters effecting on the extraction recovery were investigated. According to optimum conditions, the limit of detection and the limit of quantification were found 5 μg L−1 and 15 μg L−1 respectively with preconcentration factor of 241. The precision (RSD) (n = 6), was <5 %. The recovery of the analyte in biological samples was in the range of 96.8 and 98.6%

Keywords:

Methadone , Switchable-hydrophilicity solvent , Homogeneous liquid-liquid microextraction , Biological samples