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In this paper, we report a novel sample introduction and chemical reaction strategy by drop-by-drop inkjet injection for an electrophoretically mediated microanalysis (EMMA). This method makes it possible to achieve an on-line introduction of reactant solutions by alternately ejecting small plugs, with an overlapping region of the plugs for mixing the reactants by electrophoresis, supporting chemical reactions, followed by electrophoretic separation of the final compounds. As a proof-of-concept of the method, the EMMA of an inkjetted mixture of 4-fluoro-7-nitrobenzofurazan (NBD-F) and amino acids was carried out as a model chemical reaction. The product NBD-amino acids were quantified by detection with laser induced fluorescence. The optimal conditions for the procedure were: inkjet driving voltage: +40–44 V; pulse width: 20–24 μs; drop-by-drop injection of reactant solutions: alternately 2 drops × 25 times for the amino acid solution and the NBD-F solution; zone overlapping voltage and time: 3 kV and 2 s; incubation time after overlapping: 5 min; separation voltage: 18 kV. Under the optimized conditions, a significant enhancement in sensitivity and a sensitive quantitative analysis were realized. The results obtained were comparable with those using the off-line labeling method. This method is rapid, cost-effective, and readily automated for EMMA. [ABSTRACT FROM AUTHOR]

A spot mode-LA-AFS method has been developed for localised microanalysis of arsenic in biological tissues. The cool argon–hydrogen–air diffusion flame in the detector is able to effectively decompose LA-generated aerosol particles and atomise arsenic for fluorescence detection. After optimisation of the critical LA-AFS parameters through ablation of standards based on cellulose-based filters loaded with various arsenic species, the method was validated by comparison with LA-ICP-MS through measurement of arsenic in the leaflets of the arsenic-hyperaccumulating Chinese ladder brake fern Pteris vittata L. Both methods yielded very similar arsenic concentrations associated with parts of the leaflets. The performance characteristics of the LA-AFS method were as follows: sensitivity, 0.01 mV μg−1 g; detection limit (3× standard deviation of the noise), 11 μg g−1, or, in absolute terms, 30 pg of ablated arsenic; analysis time, ca. 1 min per spot; linearity, 0–40 mg g−1. [ABSTRACT FROM AUTHOR]

In this study, Pb isotope ratios in ferromanganese nodules were determined with good repeatability and minimum laboratory bias using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). One certified ferromanganese nodule reference material, NOD-A-1, in the form of pressed powder pellets (PPPs) produced upon ultrafine processing, was homogeneous enough to be used as an in-house matrix-matched standard or quality control sample for Pb isotopic microanalysis. The Tl normalization exponential law correction method with CTl-NIST SRM 997/CTl-sample≥ 15 (method 1) and the standard-sample-bracketing (SSB) method (method 2) were utilized to determine Pb isotope ratios with good repeatability and laboratory bias. In situ measurements of the Pb isotopes yielded a good relative standard deviation (2RSD) of ＜0.036% for 207,208Pb/206Pb and ＜0.066% for 206,207,208Pb/204Pb. In addition, the matrix effect was insignificant when the silicate glass reference material was employed as the external standard in the ferromanganese nodules using these two methods, resulting in relative errors (RE) of ＜0.064% for 206,207,208Pb/204Pb, and ＜0.046% for 207,208Pb/206Pb. The in situ Pb isotopic compositions of three Chinese ferromanganese nodules, GBW07249, GBW07295, and GBW07296, were in good agreement with those obtained by solution nebulization MC-ICP-MS (SN-MC-ICP-MS) within 2s (standard deviation) measurement uncertainties, demonstrating the reliability and robustness of our proposed analytical protocol. [ABSTRACT FROM AUTHOR]

The geochemical information preserved in mineral inclusions within zircon provides new ways to decipher the evolution of the continental crust. We present a routine procedure to analyse Pb isotopes in K-feldspar minerals and mineral inclusions in zircon by LA-MC-ICP-MS, with a spot size down to 10 μm diameter. Natural K-feldspar grains from the Shap granite (north England) were selected for their homogenous Pb isotope composition to validate the method. The Faraday cups of the Thermo Scientific Neptune Plus MC-ICP-MS were used to collect the beams for spot sizes of 150 μm and 40 μm. The average 206Pb/204Pb ratios were respectively 18.255 ± 0.27% and 18.24 ± 1.3% (2 s.d.), and they agree within their analytical uncertainties. Ion counters (MIC) were used at 10 μm to allow better determination of the low intensity signal for Pb isotopes. The 206Pb/204Pb average ratio is 18.29 ± 1.3% (2 s.d.), which is within error of the average values at spot sizes of 150 μm and 40 μm. For a 10 μm spot size internal errors on individual measurements are typically better than 1.1% (2 s.e.). K-feldspar inclusions in zircons from a monzonite intrusion in Dronning Maud Land (East Antarctica), were analysed by MIC-LA-MC-ICP-MS (10 μm spot and ∼12 μm depth). The Pb isotope ratios are similar to those previously obtained by SIMS with a Cameca IMS 1270 (∼40 × 20 μm elliptic spot and ∼2 μm depth). These SIMS data are used to validate the robustness of MIC-LA-MC-ICP-MS measurements in minute mineral inclusions. [ABSTRACT FROM AUTHOR]

In LA-ICP-MS imaging mostly lateral resolution is considered, but this work will show that linear artifacts with an angular aspect to the line scan direction may have a different spatial resolution, depending on the blur introduced by LA sampling and aerosol washout/transfer. This implies that upon scanning an irregularly shaped artifact, the spatial resolution in different locations may vary, the severity of which will be a function of the amount of “smearing” induced by the LA-ICP-MS system, invariably related to the design of the LA cell and aerosol washout/transfer efficiency. As reported previously (DOI: URL10.1021/acs.analchem.6b02052/URL), blur can be expressed as a convolution of the input image (representing the 2D elemental distribution) with point (PSF) and line (LSF) spread functions associated with ablation crater profiles and ICP-MS profiles of single pulses, respectively. Based on empirically derived PSFs and LSFs, and using a numerical calculation approach, the continuous-scanning LA-ICP-MS output of an angular-sensitive radial resolution target (Siemens star) was simulated to visualize the angular resolution dependency associated with ablation cell characteristics. [ABSTRACT FROM AUTHOR]

We report on a new laser-based technique for rapid, quantitative and automated in situ double dating (U–Pb and (U–Th–Sm)/He) of minerals, for applications in geochronology, thermochronology and geochemistry. In situ laser microanalysis offers several advantages over conventional bulk crystal methods in terms of spatial resolution, productivity, and safety. This new approach/methodology utilizes an interoperable and integrated suite of analytical instruments including a 193 nm ArF excimer laser system, quadrupole ICP-MS, quadrupole helium mass spectrometry system and swappable flow-through and ultra-high vacuum analytical chambers. We describe the analytical protocols for zircon analysis including grain mounting in Teflon, parameters for parent and daughter isotopic measurement, and standard development, and provide a freeware application for determining (U–Th–Sm)/He ‘pairwise’ ages from analytical data. The in situ double dating method described is applied to the Ellendale lamproite pipe and country rocks, Western Australia and successfully replicates conventional U–Pb and (U–Th–Sm)/He age variations determined previously by conventional techniques. [ABSTRACT FROM AUTHOR]

Microsampling strategies were evaluated for the direct analysis of dried sugar cane leaves by energy-dispersive X-ray fluorescence spectrometry (EDXRF) and laser-induced breakdown spectroscopy (LIBS). The analysis by EDXRF was carried out by irradiating each leaf fragment in its middle portion with a collimated 5 mm X-ray spot size for 50 s, allowing the determination of P, K, Ca, S, Fe, Mn and Si. EDXRF was also useful to conclude that 15 leaf fragments (37.5% of the recommended sampling area) were enough for attaining a representative analytical response from the whole diagnostic leaf. Regarding LIBS, which employs a substantial smaller ablation area (i.e., 750 µm laser spot size), sampling strategies were defined by taking into account the microchemical distribution of P, Ca, Mg, Fe, Mn, B and Si in a 9 mm × 9 mm leaf fragment area. The proposed sampling protocol relied on the interrogation (rastering) of 3 equally spaced sampling lines in each leaf fragment with 48 accumulated laser pulses per line (Nd:YAG at 1064 nm, 5 ns, 10 Hz, 50 J cm−2) perpendicular to the leaf midrib. This strategy enabled the simultaneous determination of P, K, Ca, Mg, Fe, Cu, Mn, Zn, B and Si by LIBS. Cross-validation between LIBS and EDXRF for P, K, Ca, Fe, Mn and Si predicted mass fractions presented high linear correlation coefficients of up to 0.9778 (selecting 15 leaf fragments per diagnostic leaf from 10 different sugar cane varieties). The results provide insights into a novel and promising strategy for direct and fast plant nutrition diagnosis, fostering further studies for in situ analysis of fresh leaves, strengthening the implementation of Precision Agriculture and Green Chemistry concepts. [ABSTRACT FROM AUTHOR]