Molecularly imprinted polymer as sorbent phase for disposable pipette extraction: A potential approach for creatinine analysis in human urine samples

Traditionally, creatinine determination is made by a spectrophotometric method; however, some compounds present in biological samples can interfere with creatinine determination, decreasing the sensitivity of the method in urine samples. Consequently, we report the development of a new molecularly imprinted polymer as a sorbent phase for disposable pipette extraction to determine creatinine in urine samples by high-performance liquid chromatography with UV detection. The synthesized polymer showed a high superficial area and presented a first-order kinetic reaction and a high selectivity for creatinine extraction compared to the non-molecularly imprinted polymer. The main disposable pipette extraction variables evaluated included the number of draw/eject cycles, the pH of the solution and desorption solvent type. The developed method showed an inter and intra-day precision from 1.3% to 2.0% and 0.8-1.6% respectively, accuracy values ranging from 82.3% to 102.1% respectively and recovery values ranging between 96.5% and 101.3%, with a limit of quantification of 0.302 g L^-1. The application of the developed method in real urine samples showed creatinine concentrations ranging from 0.55 to 6.61 g L^-1. Thus, the developed method was revealed to be an efficient strategy for creatinine determination, reducing analysis time (3 min) and solvent use, and increasing selectivity compared with DPX commercial sorbents.