{"id":46391,"date":"2024-06-13T09:18:13","date_gmt":"2024-06-13T15:18:13","guid":{"rendered":"https:\/\/www.tofwerk.com\/?p=46391"},"modified":"2024-06-14T06:14:32","modified_gmt":"2024-06-14T12:14:32","slug":"recent-advances-fast-data-acquisition-sp-icp-tofms","status":"publish","type":"post","link":"https:\/\/www.tofwerk.com\/ko\/recent-advances-fast-data-acquisition-sp-icp-tofms\/","title":{"rendered":"Recent Advances in Continuous Fast Data Acquisition: < 100 \u00b5s for Single-Particle ICP-TOFMS"},"content":{"rendered":"\n

Lyndsey Hendriks, Fredrik Oestlund & Martin Rittner
TOFWERK, Switzerland<\/p>\n\n\n\n

Single-particle inductively coupled plasma time-of-flight mass spectrometry (sp-ICP-TOFMS) is a powerful analytical technique for the detection and quantification of inorganic nanoparticles in a wide range of applications. While the technique is rapidly evolving into a well-established tool for nanoparticle analysis, constant development and research continue to thrive to achieve the fast acquisition capabilities. The core principle of sp-ICP-MS involves measuring a particle suspension at a sufficiently low concentration while acquiring data at a high frequency. Under these conditions, discrete particle events can be detected above the background, as opposed to conventional liquid analysis, where constant steady signals are recorded. Subsequently, the number of particle events correlates directly with the particle number concentration, while the intensity of each event correlates with the elemental mass of individual particles, respectively size.<\/p>\n\n\n\n

Here we evaluate the advanced capabilities of the TOFWERK icpTOF S2<\/a>, which features improved fast acquisition hardware designed for high time-resolved single particle analysis. More specifically, we present single-particle data acquired at acquisition speeds down to 12 \u00b5s. As fast data acquisition rate and data processing are key factors in the accuracy of the characterization of single nanoparticles, the effect of different integration times from micro- to milliseconds is investigated in detail here with regard to the distinction of signals from the background, quantification of mass and size, as well as particle number concentration (PNC).<\/p>\n\n\n\n

Experimental<\/h3>\n\n\n\n

Chemicals<\/em> \u2013 Commercial nominal spherical gold nanoparticles (30, 50 and 100 nm) as well as 60 nm AgAu coreshells were purchased from NanoComposix. The 50 and 100 nm Au nanoparticles were diluted to a final concentration of approx. 1E5 particles\/mL, while the 30 nm Au nanoparticles were diluted 10x more to reach a final PNC of 1E4 particles\/mL.<\/p>\n\n\n\n

Sp-ICP-TOFMS analysis<\/em> \u2013 In this work, the icpTOF S2 was used, with a TOF period of 12 \u03bcs. All datasets were recorded using TOFpilot <\/a>2.14, which features advanced capabilities for millisecond data acquisition.<\/p>\n\n\n\n

Data processing<\/em> \u2013 All files were processed using the Liquid Reprocessing module in TOFpilot 2.14.  For microsecond integration times, the raw data was first binned to 1ms and then, in the same way as for millisecond integration times, the Compound Poisson algorithm was used to differentiate nanoparticle events from the background [1]. The data was corrected for split events. Mass and size quantification followed the procedure of Pace et al. [2].<\/p>\n\n\n\n

Results<\/h3>\n\n\n\n
\"\"<\/a>
Figure 1.<\/strong> Overview of sp-ICP-TOFMS transient signals depending on the selected integration time: a) 12 \u03bcs, b) 120 \u03bcs and c) 1200 \u03bcs, for 60 nm AgAu coreshell nanoparticles. Thanks to the simultaneous multi-element detection capabilities of ICP-TOFMS, the silver shell (107<\/sup>Ag and 109<\/sup>Ag) as well the gold core (197<\/sup>Au) can be measured at the same time.<\/figcaption><\/figure>\n\n\n\n

<\/p>\n\n\n\n

Based on its TOF period, the icpTOF S2 can measure the full mass spectrum continuously at acquisition speeds down to 12 \u03bcs. This means that within 12 \u03bcs, ions of different mass-to-charge ratios (m\/Q) are measured continuously, and nothing is missed. As one nanoparticle event is about 0.5 ms [3], the signals of nanoparticles will present different profiles depending on the integration time used for the acquisition. Figure 1 provides the transient signals for 60 nm AgAu coreshell nanoparticles acquired with different resolution time, namely 12 \u03bcs, 120 \u03bcs and 1200 \u03bcs. As observed, when working with integration times shorter 500 \u03bcs, a time resolved profile can be measured for each nanoparticle (several data points), while with millisecond integration times, a single pulse is detected per nanoparticle (1-2 data points) [4]. Hence, a balance between too short and too long dwell times needs to be found.<\/p>\n\n\n\n