Chemical signatures in fin spine edge of Atlantic bluefin tuna (Thunnus thynnus) can serve as habitat markers of geographically distinct marine environments.

Chemical fingerprints in otoliths are commonly used as natural habitat markers in fishes. Alternatively, the first dorsal fin spine can provide valuable chemical information and may be more suitable for studying (i) endangered fish species that cannot be sacrificed for their otoliths or (ii) fishes for which otoliths might not be available because of management or commercial reasons. Here, we studied multi-element chemistry of fin spine edges collected from Atlantic bluefin tuna (ABFT; Thunnus thynnus) (Linnaeus, 1758) to investigate the utility of the fin spine edge as a natural habitat marker. We determined stable isotopic δ18O and δ13C ratios, as well as concentrations of the tracer elements Mg, Mn, Li, Ba, and Sr, at the edge of ABFT fin spines, and then we used these measures to discriminate ABFT individuals among capture regions (i.e., the eastern Atlantic Ocean or Mediterranean Sea). Isotope ratios and tracer element concentrations, and especially a combined multi-element approach, were able to effectively discriminate individuals by capture region. The Mg, Mn, Li, and δ18O concentrations were the strongest variables driving this discrimination. Overall, our results demonstrate that chemical signatures are consistently retained in the ABFT fin spine edge and support the use of fin spine edges for discerning habitat use. The fin spine chemistry as a minimally invasive sampling method, combined with otolith chemistry, genetic markers, and tagging efforts can help us to reconstruct fish movements, providing a deeper understanding of the spatial population dynamics of this iconic fish species.

Isotopic Imaging Using fsLA Single-Collector ICP-SFMS for Direct U/Th Dating of Small Archaeological Carbonates.

We present a new methodology for the U/Th dating of carbonate materials using femtosecond laser ablation single-collector inductively coupled plasma sector field mass spectrometry (fsLA single-collector ICP-SFMS), isotopic mappings, and image processing. This approach allows working on samples at very low U levels (ng·g-1). One of the major advantages of this imaging method is that it allows us to exploit deteriorated samples that could not be analyzed by conventional bulk U/Th dating methods, thanks to the identification of contaminated or leached areas at the scale of a few tens of microns and the subsequent correction for detrital 230Th incorporation. Only a few milligrams of material are required for measurement, which allows us to work on small samples such as shell fragments. The parameters of the fsLA single-collector ICP-SFMS coupling have been carefully optimized to ensure very high sensitivity detection and ultralow background while preserving good plasma robustness and a spatial resolution of 30 × 50 µm2. The accuracy was evaluated from low-level U speleothems previously dated by a conventional U/Th dating technique involving digestion, resin purification, double spike, and detection by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). U/Th ages of two archaeological samples with U at low ng·g-1 levels, a giant terrestrial snail shell and a burned ostrich eggshell, were determined. The measured U/Th ages are consistent with the expected ages determined by luminescence dating methods.

Analytical strategies for Sr and Pb isotopic signatures by MC-ICP-MS applied to the authentication of Champagne and other sparkling wines.

Wine is one of the most counterfeit product and therefore, requires certifying of its origin and provenance. For authentication purposes, analytical strategies for the determination of Sr and Pb isotopic ratios were adapted for Champagne and sparkling wines. All analytical steps have been carefully adapted and optimized regarding sample preparation, mineralization, and purification by resins as well as isotopic composition measurements on 3 different MC ICP-MS instruments. Further, a global approach using an "in-house" reference material of Champagne (ChRM) was realized and used throughout as well as routine analytical conditions to guaranty samples isotopic quality determination over 3 years. These developments allowed to select the best conditions at all steps for reaching the best precision and accuracy to be used under routine conditions for samples origin discrimination. The best condition of mineralization was obtained with a hot block system allowing both efficiency in digestion and high sample throughput. Detailed conditions of purification for both Sr and Pb isotopes were also optimized and discussed. These different optimization steps on the whole analytical chain allowed to estimate a global precision suitable to be used routinely to discriminate the origin of different Champagne samples. For Sr isotopic analysis (87Sr/86Sr), the overall external precision based on preparation replicates of ChRM was 2σ = 0.000024 (n = 36) and for the Pb isotopes analysis (208Pb/206Pb), the precision obtained on ChRM was 2σ = 0.0024 (n = 15). Finally, we have applied these developments by combining both Sr and Pb isotopic ratios in order to discriminate the origin of sparkling wines from around the world. The combined isotopic signature, using both Sr and Pb isotopes ratios, permitted a clear discrimination between certified Champagne wines and other European and Non-European sparkling wines.

Direct Online Determination of Laser-Induced Particle Size Distribution by ICPMS.

The characterization of the aerosol (size, composition, and concentration) generated by Laser Ablation is of great interest due to its impact on the analytical performances when coupled to Inductively Coupled Plasma Mass Spectrometry (ICPMS). The capabilities of High Resolution ICPMS as a direct tool to characterize nanoparticles produced by femtosecond Laser Ablation of pure copper are presented. An analytical protocol, similar to the "single particle ICPMS" technique used to characterize the size distribution of nanoparticles in solution, was developed in order to observe the signals of individual particles produced by a single ablation shot. A Visual Basic for Applications (VBA) data processing was developed to count and sort the particles as a function of their size and thus determine the particle size distribution. To check the reliability of the method, the results were compared to a more conventional technique, namely, Electrical Low Pressure Impaction (ELPI) for 4000 shots. Detection limit for the particles produced by the laser ablation of a copper foil is of a few attograms corresponding to a nanoparticle of 14 nm. The direct online determination of particle size by ICPMS gave similar results than ELPI for copper particles ejected during the ablation shot by shot at a fixed spot, from 1 to 100 shots. Particles larger than 159 nm represented less than 1% of the aerosol whose distribution was centered on 25-51 nm.

Improving Precision and Accuracy of Isotope Ratios from Short Transient Laser Ablation-Multicollector-Inductively Coupled Plasma Mass Spectrometry Signals: Application to Micrometer-Size Uranium Particles.

The isotope drift encountered on short transient signals measured by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS) is related to differences in detector time responses. Faraday to Faraday and Faraday to ion counter time lags were determined and corrected using VBA data processing based on the synchronization of the isotope signals. The coefficient of determination of the linear fit between the two isotopes was selected as the best criterion to obtain accurate detector time lag. The procedure was applied to the analysis by laser ablation-MC-ICPMS of micrometer sized uranium particles (1-3.5 µm). Linear regression slope (LRS) (one isotope plotted over the other), point-by-point, and integration methods were tested to calculate the (235)U/(238)U and (234)U/(238)U ratios. Relative internal precisions of 0.86 to 1.7% and 1.2 to 2.4% were obtained for (235)U/(238)U and (234)U/(238)U, respectively, using LRS calculation, time lag, and mass bias corrections. A relative external precision of 2.1% was obtained for (235)U/(238)U ratios with good accuracy (relative difference with respect to the reference value below 1%).

Isotope dilution mass spectrometry for quantitative elemental analysis of powdered samples by radiofrequency pulsed glow discharge time of flight mass spectrometry.

In recent years particular effort is being devoted to the development of pulsed glow discharges (PGDs) for mass spectrometry because this powering operation mode could offer important ionization analytical advantages. However, the capabilities of radiofrequency (RF) PGD coupled to a time of flight mass spectrometry (ToFMS) for accurate isotope ratio measurements have not been demonstrated yet. This work is focused on investigating different time positions along the pulse profile for the accurate measurement of isotope ratios. As a result, a method has been developed for the direct and simultaneous multielement determination of trace elements in powdered geological samples by RF-PGD-ToFMS in combination with isotope dilution mass spectrometry (IDMS) as an absolute measurement method directly traceable to the International System of Units. Optimized operating conditions were 70 W of applied radiofrequency power, 250 Pa of pressure, 2 ms of pulse width and 4 ms of pulse period, being argon the plasma gas used. To homogeneously distribute the added isotopically-enriched standards, lithium borate fusion of powdered solid samples was used as sample preparation approach. In this way, Cu, Zn, Ba and Pb were successfully determined by RF-PGD-ToF(IDMS) in two NIST Standard Reference Materials (SRM 2586 and SRM 2780) representing two different matrices of geological interest (soil and rock samples). Cu, Zn, Ba and Pb concentrations determined by RF-PGD-ToF(IDMS) were well in agreement with the certified values at 95% confidence interval and precisions below 12% relative standard deviation were observed for three independent analyses. Elemental concentrations investigated were in the range of 81-5770 mg/kg, demonstrating the potential of RF-PGD-ToF(IDMS) for a sensitive, accurate and robust analysis of powdered samples.

Elemental analyses of soil and sediment fused with lithium borate using isotope dilution laser ablation-inductively coupled plasma-mass spectrometry.

Quantitative analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) remains challenging primarily due to the lack of appropriate reference materials available for the wide variety of samples of interest and to elemental fractionation effects. Isotopic dilution mass spectrometry (IDMS) is becoming the methodology of choice to address these issues because the different isotopes of an element represent near-perfect internal standards. In this work, we investigated the lithium borate fusion of powdered solid samples, including soils, sediments, rock mine waste and a meteorite, as a strategy to homogenously distribute, i.e. equilibrate the elements and the added isotopically enriched standards. A comparison of this methodology using two pulsed laser ablation systems (ArF* excimer and Nd:YAG) with different wavelengths as well as two ICP-MS instruments (quadrupole and double-focusing sector field) was performed. Emphasis was put on using standard equipment to show the potential of the proposed strategy for its application in routine laboratories. Cr, Zn, Ba, Sr and Pb were successfully determined by LA-ICP-IDMS in six Standard Reference Materials (SRMs) representing different matrices of environmental interest. Experimental results showed the SRM fused glasses exhibited a low level of heterogeneity (intra- and inter-sample) for both natural abundance and isotopically enriched samples (RSD <3%, n=3, 1σ). A good agreement between experimental results and the certified values was also observed.

Standard addition method for laser ablation ICPMS using a spinning platform.

A method has been developed for the fast and easy determination of Pb, Sr, Ba, Ni, Cu, and Zn, which are of geological and environmental interest, in solid samples by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) using a spinning sample platform. The platform, containing a sample and a standard, is spun during the ablation, allowing the quasi-simultaneous ablation of both materials. The aerosols resulting from the ablation of sample and standard were mixed in the ablation cell allowing quantification of analytes by standard additions. The proportion of standard versus sample of the mixing can be increased by performing the ablation further from the axis of rotation. The ablated masses have been determined using a new strategy based on isotope dilution analysis. This spinning laser ablation method has been applied to the Allende meteorite and four powdered standard reference materials (SRMs) fused in lithium borate glasses: two sediments as well as a soil and a rock material. SRM 612 (Trace Elements in Glass) was also analyzed despite having a matrix slightly different from the glass standard obtained by lithium borate fusion. The deviation from the certified values was found to be less than 15% for most of the mass fractions for all the elements and samples studied, with an average precision of 10%. These results demonstrate the validity of the proposed method for the direct and fast analysis of solid samples of different matrixes by standard additions, using a single standard sample.

Putting a spin on LA-ICP-MS analysis combined to isotope dilution.

The determination of Zn, Sr, Ba, and Pb in solid samples has been achieved by laser ablation inductively coupled plasma isotope dilution mass spectrometry using a spinning platform. The fast rotation of a sample and an isotopically enriched spike placed close together on a sample holder allowed performing the isotope dilution directly inside the ablation cell. The proportion of spike versus sample of the aerosol mixture obtained has been determined online by isotope dilution in order to correct for differences in ablation rate although both materials were placed on the axis of rotation of the motor. Homogeneous, time-stable, and reusable samples were prepared by lithium borate fusion. A unique isotopically enriched spike glass was used to analyze four Standard Reference Materials of different matrix (after a simple polishing): two sediments Standard Reference Material (SRM) 1944 and SRM 2702 and two soils SRM 2586 and SRM 2711a. The proposed method yielded mass fractions with a deviation from the certified value usually lower than 12% and a precision of less than 9% RSD (except for Zn in SRM 2586 and 2711a). Although direct spiking of the solid before fusion could presumably provide better isotopic mixing, the presented methodology allows the reuse of the spike glass (thus, decreasing drastically the cost of the analysis) and is relatively faster because the spike does not need to be weighted, added, and evaporated each time. These results demonstrate the potential of this newly developed method for fast analysis of solid samples using isotope dilution at a low cost.

Direct determination of trace elements in powdered samples by in-cell isotope dilution femtosecond laser ablation ICPMS.

A method has been developed for the direct and simultaneous multielement determination of Cu, Zn, Sn, and Pb in soil and sediment samples using femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICPMS) in combination with isotope dilution mass spectrometry (IDMS). The in-cell isotope dilution fs-LA-ICPMS method proposed in this work was based on the quasi-simultaneous ablation of the natural abundance sample and the isotopically enriched solid spike, which was performed using a high repetition rate laser and a fast scanning beam device in a combined manner. Both the sample preparation procedure and the total analysis time have been drastically reduced, in comparison with previous approaches, since a unique multielement isotopically enriched solid spike was employed to analyze different powdered samples. Numerous experimental parameters were carefully selected (e.g., carrier gas flow rate, inlet diameter of the ablation cell, sample translation speed, scanner speed, etc.) in order to ensure the complete mixing between the sample and the solid spike aerosols. The proposed in-cell fs-LA-ICP-IDMS method was tested for the analysis of two soil (CRM 142R, GBW-07405) and two sediment (PACS-2, IAEA-405) reference materials, and the analysis of Cu, Zn, Sn, and Pb yielded good agreement of usually not more than 10% deviation from the certified values and precisions of less than 15% relative standard deviation. Furthermore, the concentrations were in agreement not only with the certified values but also with those obtained by ICP-IDMS after the microwave-assisted digestion of the solid samples, demonstrating therefore that in-cell fs-LA-ICP-IDMS opens the possibility for accurate and precise determinations of trace elements in powdered samples reducing the total sample preparation time to less than 5 min. Additionally, scanning electron microscope measurements showed that the aerosol generated by in-cell fs-LA-ICP-IDMS predominantly consisted of linear agglomerates of small particles (in the order of few tens of nanometers) and a few large spherical particles with diameters below 225 nm.

Sensitive detection of selenoproteins in gel electrophoresis by high repetition rate femtosecond laser ablation-inductively coupled plasma mass spectrometry.

A laser ablation-ICPMS method using an infrared (1030 nm), low-energy (39 microJ/pulse), high repetition rate (10 kHz), femtosecond laser was developed to improve the sensitivity of detection of heteroatom-containing proteins in 1D polyacrylamide gels. A 2-mm-wide lane was ablated by ultrafast (10 cm s(-1)) back-and-forth movement of a 20-microm laser beam parallel to the protein bands while the gel advanced perpendicularly. This procedure resulted in a considerable increase in detection sensitivity (>40-fold) compared to the nanosecond 266-nm laser ablation-ICPMS, mainly because of the much larger amount of ablated material introduced into the plasma on the time scale of the dwell time of the mass spectrometer. The method was applied to the specific detection in the gel of formate dehydrogenase expressed in Escherichia coli and of selenoproteins in Desulfococcus multivorans with detection limits at the low-femtomolar levels.