Determination of Substrate-Assisted Laser Desorption ICPMS Transport Efficiency of Gold Nanoparticles
| Authors | |
|---|---|
| Year of publication | 2019 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Substrate-assisted laser desorption inductively coupled plasma mass spectrometry (SALD ICPMS) is a method for fast determination of metals from dried droplets of sub-microliter sample volumes applied onto a polymer substrate, such as polyethylene terephthalate-glycol (PETG).[1] Besides using SALD ICPMS for determination of metals in dissolved forms, it can also be used for analysis of metal nanoparticles in single-particle (SP) mode.[2] An important parameter of SALD SP-ICPMS is transport efficiency; transport efficiency of 56 nm gold nanoparticles (AuNPs) was estimated to be around 60%. This contribution describes the development of a more direct method for determination of SALD transport efficiency using scanning electron microscopy (SEM). A thin chromium layer was deposited on PETG plates using a sputter coater (Q150T ES, Quorum Technologies, UK) in order to make the surface of PETG plates conductive. The stock suspension of 80 nm AuNPs (1E+10 NPs/mL BBI solutions, UK,) was diluted 70 times and volume of 3.5 nL was deposited using a piezoelectric dispenser (MJ–ABP–01–50–DLC, MicroFab Technologies, USA) on polyethylene terephthalate-glycol (PETG) plate and dried yielding ~500 AuNPs in a dried droplet. The diameter of the dried droplet was ~60 µm. In order to determine the exact number of AuNPs in a droplet, the stains were imaged using SEM (Helios 4 CX DualBeamTM, Thermo Fisher Scientific, USA). Only 106 x 106 µm square area containing the stain was left for further analysis, the surrounding chromium layer with occasionally present AuNPs was removed with Ga ion beam (Tomahawk Ion column, 30 kV, 65 nA). The squares with dried droplets were desorbed using a raster scan with 213 nm laser ablation system (UP213, New Wave Research, USA). Signal at m/z 197 was acquired by an ICP quadrupole mass spectrometer (7500ce ICPMS, Agilent, USA) with integration time 10 ms. The overall transport efficiency of 45 % was determined from numbers of AuNPs determined by SALD SP-ICPMS and SEM. Ways to enhance transport efficiency will be discussed. |
| Related projects: |