Online Detection of Ropivacaine in Drip Bags Using Polypyrrole/graphene Oxide Materials.

A novel method of measuring the concentration of the local anesthetic ropivacaine drip bags used in hospi- tals was developed using electrochemical impedance technique. Polypyrrole (Ppy)/graphene oxide (GO) composites were prepared by electrochemically polymerization over Au electrodes, which served as working electrodes. The Ppy/GO composite electrodes were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Various concentrations of ropivacaine (0.1-20 ppm) were prepared in a sample drip bag solution of 0.9 % NaCl from hostpital. The composite Ppy/1 % GO electrode exhibited strongest linearity (R2=0.960) than the Ppy electrode (R2=0.928) at a frequency of 100 kHz. The detection limits of ropivacaine on Ppy and Ppy/1 % GO were calculated as 0.11 ppm and 0.08 ppm, respectively. The proposed system yielded response and recovery times under 1 sec detecting 0.1 ppm (100 g/L) of ropivacaine; thus, the proposed online method is promising for measuring ropivacaine concentrations in drip bags. Molecular simulations and equivalent circuits were applied to explain the dynamic behavior of ropivacaine detection system using Ppy and Ppy/GO materials. [ABSTRACT FROM AUTHOR]