Determination of indometacin and acemetacin in human urine via reduced graphene oxide - based pipette tip solid-phase extraction coupled to HPLC

A rapid method for solid-phase extraction (SPE) and quantitation of the non-steroidal anti-inflammatory drugs indometacin and acemetacin in urine was developed. SPE is based in of the use of a reduced graphene oxide (rGO) in a pipette tip, and separation and quantitation is based on HPLC with a Promosil C-18 column and UV detection. The amount of sorbent, types and volumes of washing solvent and elution solvent were optimized. The results showed that the use of the rGO sorbent and a miniaturized pipette tip cartridge are distinctly superior to other sorbents including multiwalled carbon nanotubes and conventional SPE cartridges. Linear responses to indometacin and acemetacin are found for the 0.1-50 mu g mL(-1) concentration ranges, recoveries (at three spiking levels) range from 89.6 % to 95.7 %, and the relative standard deviations are a parts per thousand currency sign6.4 %.