Size-Based Analysis of Au NPs by Online Monolithic Capillary Microextraction-ICPMS.

An online hydrophilic polymer monolithic capillary microextraction (CME)-inductively coupled plasma mass spectrometry (ICPMS) analytical system was developed for the size-based analysis of Au NPs in the range of 3-40 nm. Au NPs with different particle sizes retained on the poly(acrylamide-vinylpyridine-methylene bis(acrylamide)) (poly(AA-VP-Bis)) monolithic capillary showed different elution behavior when cysteamine was used as the eluent, and the napierian logarithm of the critical eluent concentration (Ln C (cysteamine)) was linearly dependent on the particle size of Au NPs. This means that the unknown particle size of Au NPs can be deduced based on their critical eluent concentrations. The developed method was successfully used for the baseline separation of 3 and 20 nm Au NPs, as well as 10 and 30 nm Au NPs. Compared with chromatographic-based methods for the size analysis of Au NPs, the developed online poly(AA-VP-Bis) monolithic CME-ICPMS method is featured with simultaneous separation and enrichment of Au NPs, simple operation, low cost, high analytical speed, and high adsorption capacity.