Inductively Coupled Plasma Time-of-flight Mass Spectrometry Research Articles

Optofluidic Force Induction Meets Raman Spectroscopy and Inductively Coupled Plasma-Mass Spectrometry: A New Hyphenated Technique for Comprehensive and Complementary Characterizations of Single Particles.

Nanoparticles are produced at accelerating rates, are increasingly integrated into scientific and industrial applications, and are widely discharged into the environment. Analytical techniques are required to characterize parameters such as particle number concentrations, mass and size distributions, molecular and elemental compositions, and particle stability. This is not only relevant to investigate their utility for various industrial or medical applications and for controlling the manufacturing processes but also to assess toxicity and environmental fate. Different analytical strategies aim to characterize certain facets of particles but are difficult to combine to retrieve relevant parameters coherently and to provide a more comprehensive picture. In this work, we demonstrate the first online hyphenation of optofluidic force induction (OF2i) with Raman spectroscopy and inductively coupled plasma-time-of-flight-mass spectrometry (ICP-TOFMS) to harness their complementary technology-specific advantages and to promote comprehensive particle characterizations. We optically trapped individual particles on a weakly focused vortex laser beam by aligning a microfluidic flow antiparallelly to the laser propagation direction. The position of particles in this optical trap depended on the hydrodynamic diameter and therefore enabled size calibration as well as matrix elimination. Additionally, laser light scattered on particles was analyzed in a single particle (SP) Raman spectroscopy setup for the identification of particulate species and phases. Finally, particles were characterized regarding elemental composition and their distributions in mass and size using SP ICP-TOFMS. In a proof of concept, we analyzed polystyrene-based microplastic and TiO2 nanoparticles and demonstrated the opportunities provided through the coupling of OF2i with SP Raman and SP ICP-TOFMS.

Inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) with desolvating sample introduction and He collision gas for high-accuracy determination of Rh, Pd and Pt in automobile catalytic converters

A novel and selective method has been developed for high-accuracy determination of Pd, Pt and Rh in complex autocatalyst matrices using ICP-time-of-flight mass spectrometry (ICP-TOFMS).

Semiquantitative Analysis for High-Speed Mapping Applications of Biological Samples Using LA-ICP-TOFMS.

Laser ablation (LA) in combination with inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) enables monitoring of elements from the entire mass range for every pixel, regardless of the isotopes of interest for a certain application. This provides nontargeted multi-element (bio-)imaging capabilities and the unique possibility to screen for elements that were initially not expected in the sample. Quantification of a large range of elements is limited as the preparation of highly multiplexed calibration standards for bioimaging applications by LA-ICP-(TOF)MS is challenging. In this study, we have developed a workflow for semiquantitative analysis by LA-ICP-TOFMS based on multi-element gelatin micro-droplet standards. The presented approach is intended for the mapping of biological samples due to the requirement of matrix-matched standards for accurate quantification in LA-ICPMS, a prerequisite that is given by the use of gelatin-based standards. A library of response factors was constructed based on 72 elements for the semiquantitative calculations. The presented method was evaluated in two stages: (i) on gelatin samples with known elemental concentrations and (ii) on real-world samples that included prime examples of bioimaging (mouse spleen and tumor tissue). The developed semiquantification approach was based on 10 elements as calibration standards and provided the determination of 136 nuclides of 63 elements, with errors below 25%, and for half of the nuclides, below 10%. A web application for quantification and semiquantification of LA-ICP(-TOF)MS data was developed, and a detailed description is presented to easily allow others to use the presented method.

Single Particle Inductively Coupled Plasma Time-of-Flight Mass Spectrometry—A Powerful Tool for the Analysis of Nanoparticles in the Environment

Single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) has emerged as an important tool for the characterization of inorganic nanoparticles (NPs) in the environment. Although most SP-ICP-MS applications rely on the quadrupole ICP-MS (ICP-QMS), it is limited by the slow scanning speed of the quadrupole. Recent advancements in instrumentation have led to the development of inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS) which offers a viable solution. In this review, we discuss the recent advances in instrumentation and methodology of ICP-TOF-MS, followed by a detailed discussion of the applications of SP-ICP-TOFMS in analyzing NPs in the environment. SP-ICP-TOFMS has the potential to identify and quantify both anthropogenic and natural NPs in the environment, providing valuable insights into their occurrence, fate, behavior, and potential environmental risks.

Towards Automated and High-Throughput Quantitative Sizing and Isotopic Analysis of Nanoparticles via Single Particle-ICP-TOF-MS.

The work described herein assesses the ability to characterize gold nanoparticles (Au NPs) of 50 and 100 nm, as well as 60 nm silver shelled gold core nanospheres (Au/Ag NPs), for their mass, respective size, and isotopic composition in an automated and unattended fashion. Here, an innovative autosampler was employed to mix and transport the blanks, standards, and samples into a high-efficiency single particle (SP) introduction system for subsequent analysis by inductively coupled plasma-time of flight-mass spectrometry (ICP-TOF-MS). Optimized NP transport efficiency into the ICP-TOF-MS was determined to be >80%. This combination, SP-ICP-TOF-MS, allowed for high-throughput sample analysis. Specifically, 50 total samples (including blanks/standards) were analyzed over 8 h, to provide an accurate characterization of the NPs. This methodology was implemented over the course of 5 days to assess its long-term reproducibility. Impressively, the in-run and day-to-day variation of sample transport is assessed to be 3.54 and 9.52% relative standard deviation (%RSD), respectively. The determination of Au NP size and concentration was of <5% relative difference from the certified values over these time periods. Isotopic characterization of the 107Ag/109Ag particles (n = 132,630) over the course of the measurements was determined to be 1.0788 ± 0.0030 with high accuracy (0.23% relative difference) when compared to the multi-collector-ICP-MS determination.

Visualization of critical metals in marine nodules by rapid and high-resolution LA-ICP-TOFMS mapping

Polymetallic nodules are one of the most ubiquitous critical metal reservoirs in the deep sea during early diagenesis. Trace elements including REY (Rare earth elements + Y), can provide a wealth of information to document the source-to-sink (STS) processes and critical metals enrichment regimes. Element imaging is an important “see-through” technique to display the distribution of multi-elements to understand the respective concentration relationship. However, traditional elemental mapping of macro (several millimeters) and micro (tens of micrometers) areas has remained a major challenge due to the long analytical time and low lateral resolution. Here, we apply inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS), coupled to laser ablation (LA) with a low-dispersion two-volume sample cell and a dual concentric injector at both the macro- and micro-scales. LA-ICP-TOFMS mapping was applied to an entire polymetallic nodule (size of 10 * 9 mm2 @ 40 µm2 spot size, 1300 µm/s scan speed and 15 Hz frequency) and microdomains with microlayers (size of 700 * 350 µm2 @ 1 µm2, 200 µm/s and 200 Hz), respectively. The intra-nodule distribution patterns of elements are mainly controlled by the occurrence minerals. For example, the distribution patterns of some metals (e.g., Cu, Co, Ni) are similar to that of Mn, indicating these metals host in Mn-phase minerals. There is a trend of decreasing and then increasing of these elements from the inner to the outer layer, suggesting that the redox environment may have undergone a process from oxic to suboxic and then to oxic during the growth process. Our results demonstrate the feasibility of LA-ICP-TOFMS analysis on soft and porous materials, whose advantages include a shorter time and higher lateral resolution compared with traditional LA-ICP-QMS, expanding the geochemical mapping techniques for deep-sea early diagenetic sediments samples.

Reagents for Mass Cytometry.

Mass cytometry (cytometry by time-of-flight detection [CyTOF]) is a bioanalytical technique that enables the identification and quantification of diverse features of cellular systems with single-cell resolution. In suspension mass cytometry, cells are stained with stable heavy-atom isotope-tagged reagents, and then the cells are nebulized into an inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS) instrument. In imaging mass cytometry, a pulsed laser is used to ablate ca. 1 μm2 spots of a tissue section. The plume is then transferred to the CyTOF, generating an image of biomarker expression. Similar measurements are possible with multiplexed ion bean imaging (MIBI). The unit mass resolution of the ICP-TOF-MS detector allows for multiparametric analysis of (in principle) up to 130 different parameters. Currently available reagents, however, allow simultaneous measurement of up to 50 biomarkers. As new reagents are developed, the scope of information that can be obtained by mass cytometry continues to increase, particularly due to the development of new small molecule reagents which enable monitoring of active biochemistry at the cellular level. This review summarizes the history and current state of mass cytometry reagent development and elaborates on areas where there is a need for new reagents. Additionally, this review provides guidelines on how new reagents should be tested and how the data should be presented to make them most meaningful to the mass cytometry user community.

Characterization of a high-sensitivity ICP-TOFMS instrument for microdroplet, nanoparticle, and microplastic analyses

We report the capabilities of an inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) instrument for single-droplet and single-particle analysis.

Identification and quantification of Cr, Cu, and As incidental nanomaterials derived from CCA-treated wood in wildland-urban interface fire ashes

In addition to the combustion of vegetation, fires at the wildland-urban interface (WUI) burn structural materials, including chromated copper arsenate (CCA)-treated wood. This study identifies, quantifies, and characterizes Cr-, Cu-, and As-bearing incidental nanomaterials (INMs) in WUI fire ashes collected from three residential structures suspected to have originated from the combustion of CCA-treated wood. The total elemental concentrations were determined by inductively coupled plasma-time of flight-mass spectrometry (ICP-TOF-MS) following acid digestion. The crystalline phases were determined using transmission electron microscopy (TEM), specifically using electron diffraction and high-resolution imaging. The multi-element single particle composition and size distribution were determined by single particle (SP)-ICP-TOF-MS coupled with agglomerative hierarchical clustering analysis. Chromium, Cu, and As are the dominant elements in the ashes and together account for 93%, 83%, and 24% of the total mass of measured elements in the ash samples. Chromium, Cu, and As phases, analyzed by TEM, most closely match CrO3, CrO2, eskolaite (Cr2O3), CuCrO2, CuCr2O4, CrAs2O6, As2O5, AsO2, claudetite (As2O3, monoclinic), or arsenolite (As2O3, cubic), although a bona fide phase identification for each particle was not always possible. These phases occur predominantly as heteroaggregates. Multi-element single particle analyses demonstrate that Cr occurs as a pure phase (i.e., Cr oxides) as well as in association with other elements (e.g., Cu and As); Cu occurs predominantly in association with Cr and As; and As occurs as As oxides and in association with Cu and Cr. Several Cr, Cu, and As clusters were identified and the molar ratios of Cr/Cu and Cr/As within these clusters are consistent with the crystalline phases identified by TEM as well as their heteroaggregates. These results indicate that WUI fires can lead to significant release of CCA constituents and their combustion-transformed by-products into the surrounding environment. This study also provides a method to identify and track CCA constituents in environmental systems based on multi-element analysis using SP-ICP-TOF-MS.

Beyond corrosion: development of a single cell-ICP-ToF-MS method to uncover the process of microbiologically influenced corrosion.

The development of the microbiologically influenced corrosion (MIC)-specific inductively coupled plasma-time of flight-mass spectrometry (ICP-ToF-MS) analytical method presented here, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis. For this, a MIC-specific staining procedure was developed, which ensures the analysis of intact cells. It allows the analysis of archaea at a single cell level, which is extremely scarce compared to other well-characterized organisms. The detection method revealed elemental selectivity for the corrosive methanogenic strain Methanobacterium-affiliated IM1. Hence, the possible uptake of individual elements from different steel samples was investigated and results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to uptake chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The methods developed and information obtained will be used in the future to elucidate underlying mechanisms, compliment well-developed methods, such as SEM-EDS, and develop novel material protection concepts.

Mass Cytometry Tags: Where Chemistry Meets Single-Cell Analysis.

Mass cytometry is a highly multiparametric proteomic technology that allows the measurement and quantification of nearly 50 markers with single-cell resolution. Mass cytometry reagents are probes tagged with metal isotopes of defined mass and act as reporters. Metals are detected using inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS). Many different types of mass-tag reagents have been developed to afford myriad applications. We have classified these compounds into polymer-based mass-tag reagents, nonpolymer-based mass-tag reagents, and inorganic nanoparticles. Metal-chelating polymers (MCPs) are widely used to profile and quantify cellular biomarkers; however, both the range of metals that can be detected and the metal signals have to be improved. Several strategies such as the inclusion of chelating agents or highly branched polymers may overcome these issues. Biocompatible materials such as polystyrene and inorganic nanoparticles are also of profound interest in mass cytometry. While polystyrene allows the inclusion of a wide variety of metals, the high metal content of inorganic nanoparticles offers an excellent opportunity to increase the signal from the metals to detect low-abundance biomarkers. Nonpolymer-based mass-tag reagents offer multiple applications: cell detection, cell cycle property determination, biomarker detection, and mass-tag cellular barcoding (MCB). Recent developments have been achieved in live cell barcoding by targeting proteins (CD45, b2m, and CD298), by using small and nonpolar probes or by ratiometric barcoding. From this perspective, the principal applications, strengths, and shortcomings of mass-tag reagents are highlighted, summarized, and discussed, with special emphasis on mass-tag reagents for MCB. Thereafter, the future perspectives of mass-tag reagents are discussed considering the current state-of-the-art technologies.

Examination on simultaneous multi-element isotope ratio measurement by inductively coupled plasma time of flight mass spectrometry

The simultaneous multi-element isotope ratio measurement by inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS) was examined to evaluate the possibility of simultaneous multi-element determination by isotope dilution mass spectrometry (IDMS). Output from the two different ICP-TOFMS instruments (icpTOF and Optimass 9500) were examined and the figures of merit between them were determined from the analytical results of intensity ratios as isotope ratio measurements for 10 elements (137Ba/135Ba, 111Cd/112Cd, 63Cu/65Cu, 69Ga/71Ga, 60Ni/62Ni, 208Pb/206Pb, 107Ag/109Ag, 205Tl/203Tl, 238U/235U and 66Zn/68Zn). For the results, linear calibration curves for all elements, except for 235U obtained by icpTOF, with coefficient of determination (r2) of more than 0.999 could be obtained for both ICP-TOFMS instruments in the range of concentration from 1 ng mL−1 to 100 ng mL−1, even though the sensitivities of elements were slightly different. However, the trends of intensity ratios of elements observed were different between two ICP-TOFMS instruments, especially for heavier elements such as Pb, Tl and U. The icpTOF provided consistent isotope ratios at the concentrations from 1 ng mL−1 to 100 ng mL−1 for most of elements examined, although Optimass 9500 did not provide consistent isotope ratios except for Ba, Ga and Ag. From these analytical results, icpTOF appears to be the better instrument for simultaneous multi-element determination by IDMS compared to Optimass 9500. Consequently, the simultaneous IDMS of Cd, Hg and Pb by icpTOF was demonstrated to examine the possibility of simultaneous multi-element IDMS by ICP-TOFMS and the consistent analytical results with respect to the certified values could be obtained. From these results, it was expected that icpTOF could be used for simultaneous multi-element IDMS to obtain accurate and precise analytical results since it provided consistent isotope ratios of elements.

Single-particle multi-element fingerprinting (spMEF) using inductively-coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) to identify engineered nanoparticles against the elevated natural background in soils

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

Characterization of a new ICP-TOFMS instrument with continuous and discrete introduction of solutions

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

Use of Gradient Dilution to Detect and Correct Matrix Interferences in Inductively Coupled Plasma–Time-of-Flight Mass Spectrometry (ICP-TOFMS)

Our research group earlier used dispersion that occurs during flow injection to detect and reduce matrix interference in inductively coupled plasma-time-of-flight mass spectrometry (ICP-TOFMS). In the absence of a matrix interference, the ratio of signals from any two sample constituents should remain constant, independent of the dilution, over the course of a flow-injection transient. However, when an interferent is present, the signal ratio from different analytes will change with dilution, owing to the difference in severity of the interference on specific analytes. As a result, matrix interference can be recognized (flagged) by monitoring the signal ratios of two analytes over the course of a flow-injection transient; a ratio that changes over time indicates the presence of an interferent. The drawback of this earlier method was that dispersion, and therefore dilution, was somewhat element-specific, causing the ratios to wander even when no interference existed. Here, a gradient HPLC pump is used to overcome this drawback by creating a longer, better-controlled dilution. Under these conditions, variation in dispersion between elements is negligible and difficulties associated with it are reduced or eliminated. Further, when an interference exists, the optimal dilution factor to reduce the interference to an acceptable level can be found from the gradient-dilution curve as the point where the signal ratio between two elements becomes constant.

Determination of trace impurities in advanced metallic nuclear fuels by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS)

Development of a common analytical methodology for the determination of trace impurities in U–Ti, U–Zr and U–Mo alloy fuels by inductively coupled plasma mass spectrometry.

High-speed, high-resolution, multielemental laser ablation-inductively coupled plasma-time-of-flight mass spectrometry imaging: part I. Instrumentation and two-dimensional imaging of geological samples.

Low-dispersion laser ablation (LA) has been combined with inductively coupled plasma-time-of-flight mass spectrometry (ICP-TOFMS) to provide full-spectrum elemental imaging at high lateral resolution and fast image-acquisition speeds. The low-dispersion LA cell reported here is capable of delivering 99% of the total LA signal within 9 ms, and the prototype TOFMS instrument enables simultaneous and representative determination of all elemental ions from these fast-transient ablation events. This fast ablated-aerosol transport eliminates the effects of pulse-to-pulse mixing at laser-pulse repetition rates up to 100 Hz. Additionally, by boosting the instantaneous concentration of LA aerosol into the ICP with the use of a low-dispersion ablation cell, signal-to-noise (S/N) ratios, and thus limits of detection (LODs), are improved for all measured isotopes; the lowest LODs are in the single digit parts per million for single-shot LA signal from a 10-μm diameter laser spot. Significantly, high-sensitivity, multielemental and single-shot-resolved detection enables the use of small LA spot sizes to improve lateral resolution and the development of single-shot quantitative imaging, while also maintaining fast image-acquisition speeds. Here, we demonstrate simultaneous elemental imaging of major and minor constituents in an Opalinus clay-rock sample at a 1.5 μm laser-spot diameter and quantitative imaging of a multidomain Pallasite meteorite at a 10 μm LA-spot size.

Chemical Characterization of Cobalt Crust from Afanasy-Nikitin Seamount in the Eastern Indian Ocean by Inductively Coupled Plasma Time-of-Flight Mass Spectrometry

Analytical methodology was developed for the chemical characterization of cobalt crust samples collected from the Afanasy-Nikitin seamount in Eastern Equatorial Indian Ocean by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS). Concentrations of geochemically significant groups of different trace elements such as large-ion-lithophile elements (e.g., Rb, Cs), high field strength elements (e.g., Ta, Nb, Hf and Zr), rare earth elements in addition to a few major and minor elements were determined in these samples. Samples (~50 mg) were digested in closed digestion vessels for 48 h before the expulsion of Si and the residues were taken in 5 % nitric acid. 103Rh was used as an internal standard. Matrix matching external calibrations were utilized in order to compensate for the spectroscopic and non-spectroscopic interferences. The detection limits obtained for various elements were in the range 1–0.01 ng/ml for majority of the elements analyzed. Accuracy for the determination of different elements is assessed by measuring them in a few cobalt crust samples, ferromanganese nodules and similar marine sediment reference materials. Also, there is a very good agreement between the data sets obtained by ICP-TOF-MS as well as the well established ICP-quadrupole MS on cobalt crust samples. The precisions obtained in this study are <5 % RSD for majority of the elements with comparable accuracy. The results are in agreement with certified and reference values wherever available for comparison. The geochemical characteristics of these rare marine sediments have been described.

An Intercomparison Study of Analytical Methods for the Determination of Magnesium in Low Alloy Steel

AbstractIn an intercomparison study three low alloy steel materials were analyzed on their content of the trace element Mg, and five different analytical techniques were used, namely spark‐OES, inductively coupled plasma optical emission spectrometry (ICP‐OES), inductively coupled plasma time of flight mass spectrometry (ICP‐TOFMS), inductively coupled plasma quadrupole mass spectrometry (ICP‐QMS), and glow discharge mass spectrometry (GD‐MS). Solid steel discs were used for analysis with spark‐OES and GD‐MS. For the analyses with ICP‐OES, ICP‐TOFMS, and ICP‐QMS steel chips were wet‐digested in aqua regia, and the wet‐digestion was performed either in polypropylene tubes placed in a heating block or in Teflon pressure vessels using a microwave assisted system. The Mg concentrations obtained for the three steel materials were: 2.0, 2.8, and 10.3 µg g−1, respectively, and the spread in results was acceptable, giving RSD values in the range of 20–30%.

Ablative analysis of black and colored toners using LA‐ICP‐TOF‐MS for the forensic discrimination of photocopy and printer toners

AbstractPhotocopy and printer toners were analyzed using ICP‐TOF‐MS (inductively coupled plasma time‐of‐flight mass spectrometry) with laser ablation (LA). Isotopic analysis of black and colored toners allows identification and discrimination of covering materials from different producers. The results of 201 samples of black toners were analyzed according to the following chemometric methods: cluster analysis (CA) and principal component analysis (PCA). In addition, 23 samples of colored toners were tested. Chemometric manipulation of the elemental mass spectra obtained using the ‘Fingerprinting OptiMass 9500’ program showed an effective system for the rapid comparative analysis of unknown samples. Copyright © 2010 John Wiley &amp; Sons, Ltd.