TiO2 Nanoparticles Functionalized Monolithic Capillary Microextraction Online Coupled with Inductively Coupled Plasma Mass Spectrometry for the Analysis of Gd Ion and Gd-Based Contrast Agents in Human Urine

In this work, a novel method of TiO2 nanoparticles (NPs) functionalized monolithic capillary microextraction (CME) online coupling with inductively coupled plasma mass spectrometry (ICPMS) was developed for the sequential determination of Gd3+ and Gd-based contrast agents in human urine samples. The monolithic capillary was prepared by embedding anatase TiO2 NPs in the poly(methacrylic acid-ethylene glycol dimethacrylate) (MAA-EDMA) framework. The Gd3+ and Gd-based contrast agents (such as gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) and Gd-DTPA-bismethylamide (Gd-DTPA-BMA)) display different adsorption behaviors on the prepared monolithic capillary which possesses the adsorption properties. of both anatase TiO2 NPs and poly(MAA-EDMA) monolith. Under the optimized conditions, the limits of detection (LODs) were found to be 3.6, 3.2, and 4.5 ng L-1 for Gd3+, Gd-DTPA, and Gd-DTPA-BMA, respectively, which are the lowest up to date. The enrichment factor was 25-fold with the sample throughput of 5 h(-1). The proposed method was validated by the analysis of Gd3+ and Gd-DTPA in the healthy human urine samples as well as Gd3+ and Gd-DTPA-BMA in patient urine samples. It was found that only a small amount of the free Gd3+ was released from Gd-DTPA-BMA, and accurate results could be obtained since no oxidation/reduction or subtraction is involved in this method. This method is simple, sensitive, and rapid and provides a very attractive nonchromatography strategy for the speciation of Gd3+ and Gd-based contrast agents in urine samples.