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Surfactant-Based Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Determination of Corticosteroids Followed by HPLC-DAD

Surfactant-based ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) and derivatization were applied for the pretreatment of three corticosteroids prior to determination by high-performance liquid chromatography diode array detector (HPLC-DAD). An appropriate mixture of Triton X-100 (disperser solution), CCl4(Carbon tetrachloride; extraction solvent), and salicylaldehyde (derivatization reagent) was added to human urine and plasma samples. Extraction and derivatization were continuously performed. Some key parameters, including the nature and volume of extraction solvent and dispersive solvent, amount of derivatization reagent, extraction time and temperature effect were investigated. Linearity was investigated from 1 to 300 ng mL−1. All correlation coefficients of the calibration curves were higher than 0.9993. The recoveries of 80.36% to 87.60% and an enrichment factor of 50 were obtained with only 5.00 mL of sample. The LODs thus estimated were 0.014 ng mL−1 for beclomethasone dipropionate, 0.021 ng mL−1 for hydrocortisone, and 0.314 ng mL−1 for Nandroloniphenylpropionas, respectively, while the relative standard deviations(RSD) varied between 1.66% and 2.72% (n = 6). The results showed that the method is applicable to the determination of trace corticosteroids in human urine and plasma samples.