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A laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS)-based methodology is presented for Pt, Cu, and Zn bioimaging on whole kidney 3 µm sagittal sections from rats treated with pharmacological doses of cisplatin, which were sacrificed once renal damage had taken place. Pt turned out to accumulate in the kidney cortex and corticomedullary junction, corresponding to areas where the proximal tubule S3 segments (the most sensitive cells to cisplatin nephrotoxicity) are located. This demonstrates the connection between platinum accumulation and renal damage proved by histological examination of HE-stained sections and evaluation of serum and urine biochemical parameters. Cu and Zn distribution maps revealed a significant displacement in cells by Pt, as compared to control tissues. A dramatic decrease in the Pt accumulation in the cortex was observed when cilastatin was coadministered with cisplatin, which can be related to its nephroprotective effect. Excellent imaging reproducibility, sensitivity (LOD 50 fg), and resolution (down to 8 µm) were achieved, demonstrating that LA–ICP–MS can be applied as a microscopic metal detector at cellular level in certain tissues. A simple and quick approach for the estimation of Pt tissue levels was proposed, based on tissue spiking.
There is a high international priority attached to activities which reduce NOx in the atmosphere. The current level of permitted emissions is typically between 50 µmol/mol and 100 µmol/mol, but lower values are expected in the future. Currently, ambient air quality monitoring regulations also require the measurement of NOx mole fractions as low as 0.2 µmol/mol. The production of accurate standards at these levels of mole fractions requires either dilution of a stable higher concentration gas standard or production by a dynamic technique, for example one based on permeation tubes.
The CCQM-K74 key comparison was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities and standards for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol.
The measurements of this key comparison took place from June 2009 to May 2010.
Seventeen laboratories took part in this comparison coordinated by the BIPM and VSL. The key comparison reference value was based on BIPM measurement results, and the standard measurement uncertainty of the reference value was 0.042 µmol/mol.
This key comparison demonstrated that the results of the majority of the participants agreed within limits of ±3% relative to the reference value. The results of only one laboratory lay significantly outside these limits. Likewise this comparison made clear that a full interpretation of the results of the comparison needed to take into account the presence of nitric acid (in the range 100 nmol/mol to 350 nmol/mol) in the cylinders circulated as part of the comparison, as well as the possible presence of nitric acid in the primary standards used by participating laboratories.
Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
DatesIssue 1A (Technical Supplement 2012)
This pilot study compares the performance of participants in analyzing gas mixtures of nitrogen dioxide in nitrogen by comparison with in-house gravimetric standards using Fourier transformed infrared spectroscopy (FT-IR). In this study the same gas mixtures were used as in the key comparison CCQM-K74, which was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol. In the comparison CCQM-K74 most of the participants used chemiluminescence, with a small number using UV absorption or FT-IR spectroscopy, and thus it is of interest to improve understanding of the comparative performance of these techniques because they do not exhibit any cross-sensitivity to nitric acid (HNO3), which was known to be present in the mixtures used for the comparison.
The results of this pilot study indicate good consistency and a level of agreement similar to that reported in the comparison CCQM-K74, demonstrating that FT-IR can be operated as a comparison method when calibrated with appropriate gas standards and can achieve similar measurement uncertainties to chemiluminescence and UV absorption techniques.
An additional pilot study, CCQM-P110-B2, was conducted on the same gas mixtures in parallel with this pilot study. The second study addressed FT-IR spectroscopy when used to measure the gas mixtures with respect to reference spectra. The results of this second study will be reported elsewhere.
Main text. To reach the main text of this paper, click on Final Report.
The final report has been peer-reviewed and approved for publication by the CCQM-GAWG.
DatesIssue 1A (Technical Supplement 2012)
Sensitive, accurate and fast absolute quantification of intact proteins is reported using metal coded affinity tags (MeCATs) combined with gel electrophoresis (GE) separation, inductively coupled plasma mass spectrometry (ICP-MS) detection and label-specific isotope dilution analysis quantification. Two different approaches were investigated concerning the introduction of the sample into ICP-MS, mineralization of the gel and direct laser ablation (LA) of the spot. Three major advantages are remarkable in the proposed method. First, not only heteroatom-containing proteins but also all labeled proteins in the sample can be absolutely quantified preparing an isotopically enriched tracer. On the other hand, highly sensitive determination in the amol range can be performed, considerably reducing the analysis time due to the straightforward measurements by ICP-MS. Furthermore, the studied method allows accurate quantifications with different sample-to-spike ratios and using stock spikes stored for months. After the first characterization using standard proteins, human serum albumin (HSA) and transferrin (Tf) were determined in human serum to test the applicability of the method to biological samples. The results show satisfactory quantifications for the studied proteins despite the difference in concentration and the similarity in migration distances.
A method for the analysis of Pt–protein complexes in biological samples, previously subjected to cisplatin treatment, has been developed. Proteins were separated by gel electrophoresis, and those bound to Pt were detected with high sensitivity by LA-ICP-(SF)-MS. Pt-containing spots were in-gel digested with trypsin, and the peptides produced identified using nHPLC-ESI-LTQ-FT-MS/MS. The influence of protein separation conditions, staining and gel processing prior to laser ablation on Ptprotein bonds preservation have been evaluated using standard proteins incubated with cisplatin. 2-DE separation under non-reducing conditions followed by either Coomassie blue brilliant or silver staining is appropriate for Pt–protein complexes, achieving a good separating resolution of the proteins in biological samples. Direct LA-ICP-MS analysis of glycerol-treated dried gels for Pt–protein monitoring resulted in better sensitivity, more reliable relative Pt signals and a simpler and less time-consuming approach compared to the analysis of blotted membranes. Ablation of gels allowed tackling protein identification of Pt-spots in the remaining non-ablated material in the gel, making it unnecessary to run several gels in parallel for separate Pt detection and protein identification. By using this approach, Pt coordinated to proteins, such as α-2-macroglobulin, transferrin, albumin or hemoglobin, was detected in the serum from a rat treated in vivo with cisplatin after nrSDS-PAGE separation. Furthermore, the first complete LA-ICP-MS metalloprotein contour map in a 2-DE gel has been produced, in this case for the detection of Pt–protein complexes in renal proximal tubule epithelial cells (RPTECs) incubated with cisplatin. Several proteins were identified in those spots containing Pt, which may have a connection with the drug-induced nephrotoxicity mainly affecting this cell type in the kidney.
Rainfall-triggered runoff is a major driver of pesticide input in streams. Only few studies have examined the suitability of passive sampling to quantify such episodic exposures. In this study, we used Empore-TM styrene-divinylbenzene reverse phase sulfonated disks (SDB disks) and event-driven water samples (EDS) to assess exposure to 15 fungicides and 4 insecticides in 17 streams in a German vineyard area during 4 rainfall events. We also conducted a microcosm experiment to determine the SDB-disk sampling rates and provide a free-software solution to derive sampling rates under time-variable exposure. Sampling rates ranged from 0.26 to 0.77 L d-1 and time-weighted average (TWA) concentrations from 0.05 to 2.11 µg/L. The 2 sampling systems were in good agreement and EDS exceeded TWA concentrations on average by a factor of 3. Our study demonstrates that passive sampling is suitable to quantify episodic exposures from polar organic pesticides.
In this work, a routinely applicable approach is presented to characterize metal NPs. Individual droplets generated from a microdroplet generator (MDG) were merged into an aerosol generated by a pneumatic nebulizer (PN) and introduced into an ICPMS. The MDG offers high transport efficiency of individual and discrete droplets and was therefore used to establish a calibration function for mass quantification of NPs which were introduced through the PN following the single particle procedure as described elsewhere. The major advantages of such a combined configuration include fast processing of large sample volumes, fast exchanges of different sample matrixes, and the calibration of the NP signal using traceable elemental standards, thus avoiding the need to use NP reference materials or other, not always thoroughly characterized, commercially available NPs. The transport efficiency of the sample introduction is calculated based on the fact that 100% of the calibrant reaches the plasma through the MDG, whereas for the PN a NP suspension containing a known number concentration is used. Alternatively, bulk analysis of the NP material allows transport efficiency determination without any additional information from reference NPs. With this method, we could determine the size of standard silver NPs at 60.4 ± 1.0 nm and 80.0 ± 1.4 nm, respectively, which agrees with the size ranges given by the supplier (60.8 ± 6.6 nm and 79.8 ± 5.4 nm). Furthermore, we were also able to determine the NPs number concentration of the sample (Ag/Au) with a deviation of 3.2% the expected value.
The structural and magnetic properties of magnetic multi-core particles were determined by numerical inversion of small angle scattering and isothermal magnetisation data. The investigated particles consist of iron oxide nanoparticle cores (9 nm) embedded in poly(styrene) spheres (160 nm). A thorough physical characterisation of the particles included transmission electron microscopy, X-ray diffraction and asymmetrical flow field-flow fractionation. Their structure was ultimately disclosed by an indirect Fourier transform of static light scattering, small angle X-ray scattering and small angle neutron scattering data of the colloidal dispersion. The extracted pair distance distribution functions clearly indicated that the cores were mostly accumulated in the outer surface layers of the poly(styrene) spheres. To investigate the magnetic properties, the isothermal magnetisation curves of the multi-core particles (immobilised and dispersed in water) were analysed. The study stands out by applying the same numerical approach to extract the apparent moment distributions of the particles as for the indirect Fourier transform. It could be shown that the main peak of the apparent moment distributions correlated to the expected intrinsic moment distribution of the cores. Additional peaks were observed which signaled deviations of the isothermal magnetisation behavior from the non-interacting case, indicating weak dipolar interactions.
This key comparison aims to assess the core capabilities of the participants in gas analysis. Such competences include, among others, the capabilities to prepare Primary Standard gas Mixtures (PSMs), perform the necessary purity analysis on the materials used in the gas mixture preparation, the verification of the composition of newly prepared PSMs against existing ones, and the capability of calibrating the composition of a gas mixture. According to the Strategy for Key Comparisons of the Gas Analysis Working Group, this key comparison is classified as an RMO track A key comparison.
The artefacts were binary mixtures of propane in nitrogen at a nominal amount-of-substance fraction level of 1000 μmol/mol. The values and uncertainties from the gravimetric gas mixture preparation were used as key comparison reference values (KCRVs). Each transfer standard had its own KCRV. The results are generally good. All results are within ± 1 % of the KCRV.
ICP-MS is a well-established analytical method which excels by high accuracy, high dynamic range and extremely low limits of detection for most metals. Furthermore ICP-MS offers a very high multi-element coverage so that many elements of the periodic table can be detected simultaneously. In this series of lectures, we want to focus on the historical developments, fundamentals, instrumentation and novel applications of ICP-MS in the life and material sciences.