This novel single-particle multi-element fingerprinting (spMEF) method makes it possible to discriminate engineered and natural nanoparticles in complex matrices.

In this work, we evaluate the capabilities of a new commercially available inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) instrument, the icpTOF, for analysis of liquid samples with continuous and discrete sample-introduction systems.

Many modern time-of-flight mass spectrometry (TOFMS) instruments use fast analog-to-digital conversion (ADC) with high-speed digitizers to record mass spectra with extended dynamic range (compared to time-to-digital conversion). The extended dynamic range offered by ADC detection is critical for accurate measurement of transient events. However, the use of ADC also increases the variance of the measurements by sampling the gain statistics of electron multipliers (EMs) used for detection. The influence of gain statistics on the shape of TOF signal distributions is especially pronounced at low count rates and is a major contributor to measurement variance. Here, we use Monte Carlo methods to simulate low-ion-count TOFMS signals as a function of Poisson statistics and the measured pulse-height distribution (PHD) of the EM detection system. We find that a compound Poisson distribution calculated via Monte Carlo simulation effectively describes the shape of measured TOFMS signals. Additionally, we apply Monte Carlo simulation results to single-particle inductively coupled plasma (sp-ICP) TOFMS analysis. We demonstrate that subtraction of modeled TOFMS signals can be used to quantitatively uncover particle-signal distributions buried beneath dissolved-signal backgrounds. On the basis of simulated signal distributions, we also calculate new critical values (L C) that are used as decision thresholds for the detection of discrete particles. This new detection criterion better accounts for the shape of dissolved signal distributions and therefore provides more robust identification of single particles with ICP-TOFMS.

Cerium-containing nanoparticles (Ce-NPs) from geogenic and anthropogenic sources are frequently found in the environment, and the ability to determine the origins of Ce-NPs relies on the presence of other rare...

We describe trends in fast, high resolution elemental imaging by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). Recently developed low dispersion LA cells deliver quantitative transport of ablated aerosols within 10 ms and also provide enhanced sensitivity compared to conventional LA cells because the analyte ion signal becomes less diluted during aerosol transport. When connected to simultaneous ICPMS instruments, these low dispersion LA cells offer a platform for high speed and high lateral resolution shot-resolved LA-ICPMS imaging. Here, we examine the current paradigms of LA-ICPMS imaging and discuss how newly developed LA cell technology combined with simultaneous ICPMS instrumentation is poised to overcome current instrumental limitations to deliver faster, higher resolution elemental imaging.

Online microdroplet calibration is used to determine the mass and particle number concentration of inorganic nanoparticles (NPs) without the use of NP standards. This approach can be applied directly to quantify NPs in environmental matrices.

Evaluation of capabilities offered by ICP-TOFMS for various laser-ablation-based sample introduction schemes.

Here we describe the capabilities of laser-ablation coupled to inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS) for high-speed, high-resolution, quantitative three-dimensional (3D) multielemental imaging. The basic operating principles of this instrumental setup and a verification of 3D quantitative elemental imaging are provided. To demonstrate the potential of 3D LA-ICP-TOFMS imaging, high-resolution multielement images of a cesium-infiltrated Opalinus clay rock were recorded using LA with a laser-spot diameter of 5 μm coupled to ICP-TOFMS. Quantification of elements ablated from each individual laser pulse was carried out by 100% mass normalization, and the 3D elemental concentration images generated match well with the expected distribution of elements. After laser-ablation imaging, the sample surface morphology was investigated using confocal microscopy, which showed substantial surface roughness and evidence of matrix-dependent ablation yields. Depth assignment based on ablation yields from heterogeneous materials, such as Opalinus clay rock, will remain a challenge for 3D LA-ICPMS imaging. Nevertheless, this study demonstrates quantitative 3D multielemental imaging of geological samples at a considerably higher image-acquisition speed than previously reported, while also offering high spatial resolution and simultaneous multielemental detection.