Characterization of cobalt pigments found in traditional Valencian ceramics by means of laser ablation-inductively coupled plasma mass spectrometry and portable X-ray fluorescence spectrometry

In this work, a comparison of the performances of laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) and portable X-ray fluorescence (XRF) spectrometry for the characterization of cobalt blue pigments used in the decoration of Valencian ceramics is presented. Qualitative data on the elemental composition of the blue pigments obtained using both techniques show a good agreement. Moreover, the results clearly illustrate that potters utilized different kinds of cobalt pigments in different historical periods.

While both techniques seem suitable for the proposed task, they show different strengths and weaknesses. Portable X-ray fluorescence spectrometry is a cheaper and totally non-destructive technique, capable of providing fast and reliable results at the mg g⁻¹ level. LA-ICPMS, on the other hand, offers a much higher detection power and better spatial resolution, but its use results in some sample damage (sample consumption at the μg level), while it is a more expensive and non-portable technique.     

Femtosecond laser ablation: Experimental study of the repetition rate influence on inductively coupled plasma mass spectrometry performance

This paper demonstrates the feasibility of performing bulk chemical analysis based on laser ablation for good lateral resolution with only nominal mass ablated per pulse. The influence of repetition rate (1–1000 Hz) and scan speed (1–200 µm/s) using a low energy (30 µJ) and a small spot size (~ 10 µm) UV-femtosecond laser beam was evaluated for chemical analysis of silica glass samples, based on laser ablation sampling and inductively coupled plasma mass spectrometry (ICP-MS). Accuracy to approximately 14% and precision of 6% relative standard deviation (RSD) were measured.     

Elemental ratios for characterization of quantum-dots populations in complex mixtures by asymmetrical flow field-flow fractionation on-line coupled to fluorescence and inductively coupled plasma mass spectrometry

Separation and identification of nanoparticles of different composition, with similar particle diameter, coexisting in heterogeneous suspensions of polymer-coated CdSe/ZnS quantum dots (QDs) have been thoroughly assessed by asymmetric flow field-flow fractionation (AF4) coupled on-line to fluorescence and inductively coupled plasma mass spectrometry (ICPMS) detectors. Chemical characterization of any previously on-line separated nanosized species was achieved by the measurement of the elemental molar ratios of every element involved in the synthesis of the QDs, using inorganic standards and external calibration by flow injection analysis (FIA). Such elemental molar ratios, strongly limited so far to pure single nanoparticles suspensions, have been achieved with adequate accuracy by coupling for the first time an ICP-QQQ instrument to an AF4 system. This hyphenation turned out to be instrumental to assess the chemical composition of the different populations of nanoparticles coexisting in the relatively complex mixtures, due to its capabilities to detect the hardly detectable elements involved in the synthesis. Interestingly such information, complementary to that obtained by fluorescence, was very valuable to detect and identify unexpected nanosized species, present at significant level, produced during QDs synthesis and hardly detectable by standard approaches.     

Sorptive thin film microextraction followed by direct solid state spectrofluorimetry: A simple,rapid and sensitive method for determination of carvedilol in human plasma

A poly acrylate-ethylene glycol (PA-EG) thin film is introduced for the first time as a novel polar sorbent for sorptive extraction method coupled directly to solid-state spectrofluorimetry without the necessity of a desorption step. The structure, polarity, fluorescence property and extraction performance of the developed thin film were investigated systematically. Carvedilol was used as the model analyte to evaluate the proposed method. The entire procedure involved one-step extraction of carvedilol from plasma using PA-EG thin film sorptive phase without protein precipitation. Extraction variables were studied in order to establish the best experimental conditions. Optimum extraction conditions were the followings: stirring speed of 1000 rpm, pH of 6.8, extraction temperature of 60 °C, and extraction time of 60 min. Under optimal conditions, extraction of carvedilol was carried out in spiked human plasma; and the linear range of calibration curve was 15–300 ng mL⁻¹ with regression coefficient of 0.998. Limit of detection (LOD) for the method was 4.5 ng mL⁻¹. The intra- and inter-day accuracy and precision of the proposed method were evaluated in plasma sample spiked with three concentration levels of carvedilol; yielding a recovery of 91–112% and relative standard deviation of less than 8%, respectively. The established procedure was successfully applied for quantification of carvedilol in plasma sample of a volunteer patient. The developed PA-EG thin film sorptive phase followed by solid-state spectrofluorimetric method provides a simple, rapid and sensitive approach for the analysis of carvedilol in human plasma.     

A novel approach for analysis of oligonucleotide-cisplatin interactions by continuous elution gel electrophoresis coupled to isotope dilution inductively coupled plasma mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry

In this work we present a novel approach for in vitro studies of cisplatin interactions with 8-mer oligonucleotides. The approach is based on the recently developed coupling of continuous elution gel electrophoresis (GE) to an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS) with the aim of monitoring the interaction process between this cytostatic drug and the nucleotides. In contrast to existing methods, the electrophoretic separation conditions used here allow both the determination of the reaction kinetics in more detail as well as the observation of dominant intermediates. Two different nucleotides sequences have been investigated for comparison purposes, one containing two adjacent guanines (5'-TCCGGTCC-3') and one with a combination of thymine and guanine (5'-TCCTGTCC-3'), respectively. In order to gain further structural information, MALDI-TOF MS measurements have been performed after fraction collection. This allows for identification of the intermediates and the final products and confirms the stepwise coordination of cisplatin via monoadduct to bisadduct formation. Furthermore, the ICP-MS results were quantitatively evaluated in order to calculate the kinetics of the entire process.     

Comparative study of atomic fluorescence spectroscopy and inductively coupled plasma mass spectrometry for mercury and arsenic multispeciation

Mercury and arsenic are two elements of undoubted importance owing to their toxic character. Although speciation of these elements has been developed separately, in this work for the first time the speciation of As and Hg using two atomic fluorescence detectors in a sequential ensemble is presented. A coupling based on the combination of high-performance liquid chromatography (where mercury and arsenic species are separated) and two atomic fluorescence detectors in series, with several online treatments, including photooxidation (UV) and hydride generation, has allowed the determination of mercury and arsenic compounds simultaneously. The detection limits for this device were 16, 3, 17, 12 and 8 ng mL^–1 for As^III, monomethylarsinic acid, As^V, Hg²⁺ and methylmercury, respectively. This coupling was compared with an analogous one based on inductively coupled plasma–mass spectrometry (ICP-MS) detection, with detection limits of 0.7, 0.5, 0.8, 0.9 and 1.1 ng mL^–1, respectively. Multispeciation based on ICP-MS exhibits better sensitivity than the coupling based on tandem atomic fluorescence, but this second device is a very robust system and exhibits obvious advantages related to the low cost of acquisition and maintenance, as well as easy handling, which makes it a suitable system for routine laboratories.     

The in vivo biodistribution and fate of CdSe quantum dots in the murine model: a laser ablation inductively coupled plasma mass spectrometry study

Understanding the cytotoxicity of quantum dots strongly relies upon the development of new analytical techniques to gather information about various aspects of the system. In this study, we demonstrate the in vivo biodistribution and fate of CdSe quantum dots in the murine model by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). By comparing the hot zones of each element acquired from LA-ICP-MS with those in fluorescence images, together with hematoxylin and eosin-stained images, we are able to perceive the fate and in vivo interactions between quantum dots and rat tissues. One hour after intravenous injection, we found that all of the quantum dots had been concentrated inside the spleen, liver and kidneys, while no quantum dots were found in other tissues (i.e., muscle, brain, lung, etc.). In the spleen, cadmium-114 signals always appeared in conjunction with iron signals, indicating that the quantum dots had been filtered from main vessels and then accumulated inside splenic red pulp. In the liver, the overlapped hot zones of quantum dots and those of phosphorus, copper, and zinc showed that these quantum dots have been retained inside hepatic cells. Importantly, it was noted that in the kidneys, quantum dots went into the cortical areas of adrenal glands. At the same time, hot zones of copper appeared in proximal tubules of the cortex. This could be a sign that the uptake of quantum dots initiates certain immune responses. Interestingly, the intensity of the selenium signals was not proportional to that of cadmium in all tissues. This could be the result of the decomposition of the quantum dots or matrix interference. In conclusion, the advantage in spatial resolution of LA-ICP-MS is one of the most powerful tools to probe the fate, interactions and biodistribution of quantum dots in vivo.     

Comparative study of LiMn2O4 thin film cathode grown at high, medium and low temperatures by pulsed laser deposition

LiMn₂O₄ thin films with different crystallizations were respectively grown at high, medium and low temperatures by pulsed laser deposition (PLD). Structures, morphologies and electrochemical properties of these three types of thin films were comparatively studied. Films grown at high temperature (?873 K) possessed flat and smooth surfaces and were highly crystallized with different textures and crystal sizes depending on the deposition pressure of oxygen. However, films deposited at low temperature (473 K) had rough surfaces with amorphous characteristics. At medium temperature (673 K), the film was found to consist mainly of nano-crystals less than 100 nm with relatively loose and rough surfaces, but very dense as observed from the cross-section. The film deposited at 873 K and 100 mTorr of oxygen showed an initial discharge capacity of 54.3 μAh/cm² μm and decayed at 0.28% per cycle, while the amorphous film had an initial discharge capacity of 20.2 μAh/cm² μm and a loss rate of 0.29% per cycle. Compared with the highly crystallized and the amorphous films, nano-crystalline film exhibited higher potential, more capacity and much better cycling stability. As high as 61 μAh/cm² μm of discharge capacity can be achieved with an average decaying rate of only 0.032% per cycle up to 500 cycles. The excellent performance of nano-crystalline film was correlated to its microstructures in the present study.     

A speciation methodology to study the contributions of humic-like and fulvic-like acids to the mobilization of metals from compost using size exclusion chromatography-ultraviolet absorption-inductively coupled plasma mass spectrometry and deconvolution analysis

High performance size-exclusion chromatography (HP-SEC) with UV absorption for organic matter detection and inductively coupled plasma mass spectrometry (ICP-MS) for elemental detection have been used to study the mobilization of metals from compost as a function of pH and the molecular mass of their complexes with dissolved organic matter (DOM). Due to its heterogeneous nature, organic matter mobilized from compost shows a continuous distribution of molecular masses in the range studied (up to 80 kDa). In order to differentiate between the contribution of humic and fulvic acids (FA) to the organic matter mobilized in the pH range 5-10, their UV absorption chromatographic profiles have been deconvoluted with respect to the adjusted gaussian profiles of the humic and fulvic acids isolated from compost. Results show a preponderant contribution of fulvic acids at low pH values and an increasing percentage of humic acids (HA) mobilized at basic pH (up to 49% of total DOM at pH 10). A similar deconvolution procedure has been applied to the ICP-MS chromatograms of selected metals (Co, Cu, Pb and Bi). In general, both fulvic and humic acids contribute to the mobilization of divalent transition metals, such as copper or cobalt, whereas bismuth or lead are preferably associated to humic acids. Non-humic substances (HS) also contribute to the mobilization of cations, especially at acidic pHs. These conclusions have been extended to different elements based on deconvolution analysis results at pH 7.     

A comparison of laser ablation inductively coupled plasma mass spectrometry,micro X-ray fluorescence spectroscopy,and laser induced breakdown spectroscopy for the discrimination of automotive glass

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), micro X-ray fluorescence spectroscopy (μXRF), and laser induced breakdown spectroscopy (LIBS) are compared in terms of discrimination power for a glass sample set consisting of 41 fragments. Excellent discrimination results (> 99% discrimination) were obtained for each of the methods. In addition, all three analytical methods produced very similar discrimination results in terms of the number of pairs found to be indistinguishable. The small number of indistinguishable pairs that were identified all originated from the same vehicle. The results also show a strong correlation between the data generated from the use of µXRF and LA-ICP-MS, when comparing µXRF strontium intensities to LA-ICP-MS strontium concentrations. A 266 nm laser was utilized for all LIBS analyses, which provided excellent precision (< 10% RSD for all elements and < 10% RSD for all ratios, N = 5). The paper also presents a thorough data analysis review for forensic glass examinations by LIBS and suggests several element ratios that provide accurate discrimination results related to the LIBS system used for this study. Different combinations of 10 ratios were used for discrimination, all of which assisted with eliminating Type I errors (false exclusions) and reducing Type II errors (false inclusions). The results demonstrate that the LIBS experimental setup described, when combined with a comprehensive data analysis protocol, provides comparable discrimination when compared to LA-ICP-MS and μXRF for the application of forensic glass examinations. Given the many advantages that LIBS offers, most notably reduced complexity and reduced cost of the instrumentation, LIBS is a viable alternative to LA-ICP-MS and μXRF for use in the forensic laboratory.     

Imaging of metals in biological tissue by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS): state of the art and future developments

Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) is well established as a sensitive trace and ultratrace analytical technique with multielement capability for bioimaging of metals and studying metallomics in biological and medical tissue. Metals and metalloproteins play a key role in the metabolism and formation of metal‐containing deposits in the brain but also in the liver. In various diseases, analysis of metals and metalloproteins is essential for understanding the underlying cellular processes. LA–ICP–MS imaging (LA–ICP–MSI) combined with other complementary imaging techniques is a sophisticated tool for investigating the regional and cellular distribution of metals and related metal‐containing biomolecules. On the basis of successful routine techniques for the elemental bioimaging of cryosections by LA–ICP–MSI with a spatial resolution between 200 and ~10 µm, the further development used online laser microdissection ICP–MSI to study the metal distribution in small biological sample sections (at the cellular level from 10 µm to the submicrometer range). The use of mass spectrometric imaging of metals and also nonmetals is demonstrated on a series of biological specimens. This article discusses the state of the art of bioimaging of metals in thin biological tissue sections by LA–ICP–MSI with spatial resolution at the micrometer scale, future developments and prospects for quantitative imaging techniques of metals in the nanometer range. In addition, combining quantitative elemental imaging by LA/laser microdissection–ICP–MSI with biomolecular imaging by matrix‐assisted laser desorption/ionization–MSI will be challenging for future life science research. Copyright © 2013 John Wiley & Sons, Ltd.     

Femtosecond laser ablation inductively coupled plasma mass spectrometry: Transport efficiencies of aerosols released under argon atmosphere and the importance of the focus position

Although the utilization of helium as aerosol carrier has been shown to improve both accuracy and sensitivity of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), occasionally, argon is being used due to practical and economic reasons. In order to provide more insight into the mechanisms underlying these performance differences, in this study, transport efficiencies of aerosols released by NIR- and UV-femtosecond laser ablation (LA) of brass applying laminar or turbulent in-cell flow conditions and argon as carrier gas were measured. Aerosol particles were collected by low-pressure impaction or filtered by fine porous membranes. On the basis of aerosol masses collected and mass differences derived from target weighing prior to and after LA, transport efficiencies approximately varied in between 75% and 95%. In addition, LA of a thin Cr layer was performed which allowed to release a well-defined amount of material and, thus, to correct mass balances for debris accumulating around the crater rim. The total aerosol mass released during LA was found to be strongly dependent on the relative focus position, i.e. surface area irradiated, even if the laser pulse energy delivered to the target was kept constant. Furthermore, a physical model only making use of input parameters such as laser spot size and pulse energy was implemented to qualitatively describe the correlation between aerosol mass and laser focus position.     

Metallurgical and chemical characterization of copper alloy reference materials within laser ablation inductively coupled plasma mass spectrometry: Method development for minimally-invasive analysis of ancient bronze objects

The chemical composition of ancient metal objects provides important information for manufacturing studies and authenticity verification of ancient copper or bronze artifacts. Non- or minimal-destructive analytical methods are preferred to mitigate visible damage. Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) enables the determination of major elements as well as impurities down to lower ppm-levels, however, accuracy and precision of analysis strongly depend on the homogeneity of reference materials used for calibration. Moreover, appropriate analytical procedures are required e.g. in terms of ablation strategies (scan mode, spot size, etc.). This study reviews available copper alloy (certified) reference materials — (C)RMs from different sources and contributes new metallurgical data on homogeneity and spatial elemental distribution. Investigations of the standards were performed by optical and scanning electron microscopy with X-ray spectrometry (SEM-EDX) for the following copper alloy and bronze (certified) reference materials: NIST 454, BAM 374, BAM 211, BAM 227, BAM 374, BAM 378, BAS 50.01-2, BAS 50.03-4, and BAS 50.04-4. Additionally, the influence of inhomogeneities on different ablation and calibration strategies is evaluated to define an optimum analytical strategy in terms of line scan versus single spot ablation, variation of spot size, selection of the most appropriate RMs or minimum number of calibration reference materials.     

Imaging of uranium on rat brain sections using laser ablation inductively coupled plasma mass spectrometry: a new tool for the study of critical substructures affined to heavy metals in tissues

The specific toxicity of trace metals and compounds largely depends on their bioavailability in different organs or compartments of the organism considered. Imaging mass spectrometry (IMS) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with a spatial resolution in the 100 microm range was developed and employed to study heavy metal distribution in brain tissues for toxicological screening. Rat brain post-mortem tissues were stained in an aqueous solution of either uranium or neodymium (metal concentration 100 microg g(-1)) for 3 h. The incubation of heavy metal in thin slices of brain tissue is followed by an imaging mass spectrometric LA-ICP-MS technique. Stained rat brain tissue (thickness 30 microm) were scanned with a focused laser beam (wavelength 266 nm, diameter of laser crater 100 microm and laser power density 3 x 10(9) W cm(-2)). The ion intensities of (235)U(+), (238)U(+), (145)Nd(+) and (146)Nd(+) were measured by LA-ICP-MS within the ablated area. For quantification purposes, matrix-matched laboratory standards were prepared by dosing each analyte to the pieces of homogenized brain tissue. Imaging LA-ICP-MS allows structures of interest to be identified and the relevant dose range to be estimated. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Layer-by-layer chemical deposition technique for thin film assembly of deposited nano-sized magnesium(II)-5,7-dinitro-8-hydroxyquinolate: Characterization and spectral-optical-electrical properties

Layer-by-layer (LBL) chemical deposition technique was implemented as a low cost and efficient methodology for rapid synthesis and assembly of deposited thin films of nano-sized magnesium(II)-5,7-dinitro-8-hydroxyquinolate complex, Mg[((NO₂)₂-8HQ)₂]. The stoichiometry of deposited nano-sized complex was characterized as a 1:2 ratio based on metal to ligand without contribution of the nitro-group. Further structural characterization and identification were also monitored by using Fourier Transform infrared spectroscopy (FT-IR) in order to confirm the possible mode of bonding in the deposited nano-sized Mg[((NO₂)₂-8HQ)₂] complex. Thermal gravimetric analysis (TGA) of the ligand and complex were studied and compared to evaluate the possible incorporated thermal stability characteristics. Surface imaging of assembled thin film was performed by using scanning electron microscopy (SEM) to confirm high homogeneity in surface particles distribution with average particle size in the range of 30-50 nm. The absorption spectrum of Mg[((NO₂)₂-8HQ)₂] thin film was recorded in the spectral region 250-1000 nm. The optical transmission and reflection spectra of the films have been recorded within the wavelength range 250-2500 nm. The optical parameters of the films, such as absorption index, α, refractive index, n, band gap, E_g, dielectric constants, ε₁ and ε₂ and dissipation factor, tan δ, have been also determined. Two activation energies were determined from the temperature dependence of the dark electrical conductivity. Hopping conduction parameters of Mg[((NO₂)₂-8HQ)₂] have been calculated by employing the variable range hopping model.     

Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry

Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ³⁰Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ³⁰Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g⁻¹-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ simultaneous stable isotope measurement and chemical composition analysis LASS-ICP-MS in combination with MC-ICP-MS is the method of choice.     

Development of a liquid chromatography with mass spectrometry method for the determination of gelsemine in rat plasma and tissue: Application to a pharmacokinetic and tissue distribution study

Gelsemine from Gelsemium elegans Benth is a potential anesthetic and analgesic agent with no physical dependence and opiate addiction. This study was aimed at developing an ultrafast liquid chromatography coupled to tandem mass spectrometry method to quantify gelsemine in rat plasma and tissues. Plasma and tissues were processed with acetonitrile precipitation, and dendrobine was chosen as the internal standard. Sample separation was performed on an ACQUITY HSS T3 column. The mobile phase consisted of acetonitrile and 0.1% formic acid aqueous solution. Multiple reactions monitoring mode was utilized to detect the compounds of interest. The mass spectrometer was operated in the positive ion mode for detection. The MS/MS ion transitions monitored were m/z 323.2→70.5 for gelsemine and 264.2→108.05 for dendrobine, respectively. The calibration curves were linear over the range of 1–500 ng/mL in all biological matrices. The lower limit of quantification for rats plasma and tissues was 1.0 ng/mL. The values for inter‐ and intraday precision and accuracy were well within the ranges acceptable (< 15%). It was successfully applied to the pharmacokinetic and tissue distribution studies of gelsemine after intravenous doses of 5, 2, and 0.5 mg/kg in rats. These data of gelsemine would be useful for clinical application and further development.     

Determination of plutonium and other transuranic elements by inductively coupled plasma mass spectrometry: A historical perspective and new frontiers in the environmental sciences

Inductively coupled plasma mass spectrometry (ICPMS), particularly with sector field mass analyzers (SF-ICPMS), has emerged in the past several years as an excellent analytical technique for rapid, highly sensitive determination of transuranic elements (TRU) in environmental samples. SF-ICPMS has advantages of simplicity of sample preparation, high sample throughput, widespread availability in laboratories worldwide, and relatively straightforward operation when compared to other competing mass spectrometric techniques. Arguably, SF-ICPMS is the preferred technique for routine, high-throughput determination of ²³⁷Np and the Pu isotopes, excepting ²³⁸Pu, at fg-pg levels in environmental samples. Many research groups have now demonstrated the SF-ICPMS determination of ^239 + 240Pu activities, ²⁴⁰Pu/²³⁹Pu and other Pu atom ratios in several different application areas. Many studies have examined the relative contribution of global fallout vs. local/regional Pu sources in the environment through measurement of ²⁴⁰Pu/²³⁹Pu and, in some cases, ²⁴¹Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu. “Stratospheric fallout”, which was deposited from thermonuclear tests, conducted largely during the 1952–1964 time period, is characterized by a well-defined ²⁴⁰Pu/²³⁹Pu of ~ 0.18, while most other sources have different ratios. Examples of local/regional Pu sources are the Nevada Test Site, the Chernobyl plume, and accidents at Palomares, Spain and Thule, Greenland. The determination of Pu activities and atom ratios has stimulated much interest in the use of Pu as a marine tracer; several studies have shown that Pu is transported over long distances by ocean currents. ²⁴⁰Pu/²³⁹Pu ratios > 0.20 in sediments and seawater of the North Pacific are ascribed to ocean current transport of fallout from the Pacific Proving Ground. In nuclear forensics, much effort is focused on detection and fingerprinting of small amounts of TRU in environmental samples consisting of bulk material or individual isolated particles. Activity measurements of ^239 + 240Pu, determined by SF-ICPMS, have the potential to supplement and/or replace ¹³⁷Cs as a tracer of erosion, deposition, and sedimentation. Undoubtedly, the application of SF-ICPMS in TRU analysis will continue to expand, witness new developments, and generate interesting unforeseen applications in upcoming years.