A new kind of polystyrene/polyethyleneimine nanofibres coordinated with palladium for fast and efficient extraction of methotrexate and its polyglutamate metabolites in different matrices.

Methotrexate (MTX) is a drug that has long been used in high doses as an anti-cancer drug and lately in low doses as a treatment for autoimmune diseases. It is necessary to be determined in various matrices because the drug has a narrow therapeutic range and a high persistence in the environment. Since MTX and its polyglutamate metabolites (MTXPGs) have strong polarity and the potential to be converted during sample processing, rapid and efficient extraction of these targets has provided technical challenges for development of analytical methods for them. A new Pd(ii)/polyethyleneimine (PEI)/polystyrene (PS) nanofibre was prepared and characterized by X-ray diffraction, FTIR spectroscopy, thermal analysis, scanning electron microscopy and transmission electron microscopy, etc. The nanofibre was applied as a sorbent to extract MTX and MTXPGs in whole blood and MTX in urine and water. The extracted analytes were then desorbed by a water solution containing 10% methanol and 20% ammonium hydroxide (v/v) and eventually quantified by high performance liquid chromatography. The peak area of the target substances in the extraction solution and its concentration were linear in the range of 20.0 (∼37.8 to 1000 ng/mL); intraday and interday RSD were 4.6-6.4% and 5.7-14.6%, respectively. The detection limit of this method was 6.0-11.3 ng/mL. The results showed that the method can be used for the determination of MTX and MTXPGs in human whole blood and MTX in urine/water samples.