Inductively Coupled Plasma Mass Spectrometry-Based Method for the Specific Quantification of Sulfenic Acid in Peptides and Proteins

A robust ICPMS-based method is introduced to obtain relative and absolute quantification of sulfenic acid (SA) in peptides and proteins. A new metal-containing reagent (Ln-DOTA-Dimedone) devised to react specifically with SA has been developed. The lanthanide-containing metal-coded affinity tag (Ln-MeCAT) was used to quantify thiol residues. We presented two approaches which allow the parallel and consecutive determination of SA and thiols in peptide and protein samples. The high sensitivity, structure-independent signal, and multiplexing capabilities of ICPMS together with the specificity of Ln-DOTA-Dimedone and Ln-MeCAT toward sulfenic acid and thiol residues, respectively, allow the characterization of various biological states and offer closer insight onto thiol-sulphenic acid equilibria which are involved in intracellular redox-mediated events altering structure and function of proteins in important diseases

Investigation of a Combined Microdroplet Generator and Pneumatic Nebulization System for Quantitative Determination of Metal-Containing Nanoparticles Using ICPMS

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

Bridging the Gap between Molecular and Elemental Mass Spectrometry: Higher Energy Collisional Dissociation (HCD) Revealing Elemental Information

Molecular mass spectrometry has been applied to simultaneously obtain molecular and elemental information from metal-containing species. Energy tuning of the higher-energy collision dissociation (HCD) fragmentation cell allows the controlled production of typical peptide fragments or elemental reporter ions informing about the metallic content of the analyzed species. Different instrumental configurations and fragmentation techniques have been tested, and the efficiency extracting the elemental information has been compared. HCD fragmentation operating at very high energy led to the best results. Platinum, lanthanides, and iodine reporter ions from peptides interacting with cisplatin, peptides labeled with lanthanides-MeCAT-IA, and iodinated peptides, respectively, were obtained. The possibility to produce abundant molecular and elemental ions in the same analysis simplifies the correlation between both signals and open pathways in metallomics studies enabling the specific tracking of metal-containing species. The proposed approach has been successfully applied to <i>in solution</i> standards and complex samples. Moreover, interesting preliminary MALDI-imaging experiments have been performed showing similar metal distribution compared to laser ablation (LA)-ICPMS