Guenter Allmaier

Corrosion properties of ammonium based ionic liquids evaluated by SEM-EDX, XPS and ICP-OES

Two ammonium-based ionic liquids (IL) with the potential to be used as lubricants were investigated with respect to their corrosion ability. With the intention to reduce the potential negative environmental impact of lubricant ILs, (2-hydroxyethyl)-trimethyl-ammonium (choline) was chosen as the cation and compared with butyl-trimethyl-ammonium. Two commonly used metals were immersed in the selected ILs to simulate severe conditions. For each material, a corrosion inhibitor was selected and added to the respective IL to confer corrosion protection. The corrosive behavior of the ILs was determined by specially designed small-scale experiments and monitoring of the metal content in the ILs by inductively coupled plasma optical emission spectrometry (ICP-OES), showing preferable properties of the choline IL. After the corrosion experiments, the morphology and the elemental composition of the corroded metal surfaces exposed to ILs were studied by scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectroscopy (XPS). Besides ICP-OES, surface analysis to determine the chemical composition on the surface and to identify corrosion products contributed to the qualitative evaluation of the effectiveness of the corrosion inhibitors. It was also possible to show that the corrosion properties of ILs can be significantly improved by the addition of selected corrosion inhibitors.

Comparison of various nano-differential mobility analysers (nDMAs) applying globular proteins

The demand for analysis of nanosized particles and assemblies of biologic and inorganic origin has increased in the recent decade together with the growing development of biotechnology and nanotechnology. Recent developments of electrostatic differential mobility analysis (DMA) provide an excellent characterization tool in the nanometer size range. With an increasing number of available nano-DMA (nDMA) systems, the question of data comparability and implementation of possible calibration procedures arise. Here we present analysis of proteins in a range between 3 nm (5.7 kDa) and 15 nm (660 kDa) with five different nDMA systems. Results show differences in the obtained sizes up to 15% between different nDMA systems, which consequently leads to the conclusion that a calibration procedure for each nDMA is necessary when applying such systems for the analysis of nanoparticles with respect to size and molecular mass.

Ultrahigh-performance liquid chromatography/electrospray ionization linear ion trap Orbitrap mass spectrometry of antioxidants (amines and phenols) applied in lubricant engineering.

RATIONALE For the qualification and quantification of antioxidants (aromatic amines and sterically hindered phenols), most of them applied as lubricant additives, two ultrahigh-performance liquid chromatography (UHPLC) electrospray ionization mass spectrometric methods applying the positive and negative ion mode have been developed for lubricant design and engineering thus allowing e.g. the study of the degradation of lubricants. METHODS Based on the different chemical properties of the two groups of antioxidants, two methods offering a fast separation (10 min) without prior derivatization were developed. In order to reach these requirements, UHPLC was coupled with an LTQ Orbitrap hybrid tandem mass spectrometer with positive and negative ion electrospray ionization for simultaneous detection of spectra from UHPLC-high-resolution (HR)-MS (full scan mode) and UHPLC-low-resolution linear ion trap MS(2) (LITMS(2)), which we term UHPLC/HRMS-LITMS(2). RESULTS All 20 analytes investigated could be qualified by an UHPLC/HRMS-LITMS(2) approach consisting of simultaneous UHPLC/HRMS (elemental composition) and UHPLC/LITMS(2) (diagnostic product ions) according to EC guidelines. Quantification was based on an UHPLC/LITMS(2) approach due to increased sensitivity and selectivity compared to UHPLC/HRMS. Absolute quantification was only feasible for seven analytes with well-specified purity of references whereas relative quantification was obtainable for another nine antioxidants. All of them showed good standard deviation and repeatability. CONCLUSIONS The combined methods allow qualitative and quantitative determination of a wide variety of different antioxidants including aminic/phenolic compounds applied in lubricant engineering. These data show that the developed methods will be versatile tools for further research on identification and characterization of the thermo-oxidative degradation products of antioxidants in lubricants.

Electrospray ionization and atmospheric pressure matrix‐assisted laser desorption/ionization mass spectrometry of antioxidants applied in lubricants

The aim of this study was to investigate the utility of ion trap mass spectrometry (ITMS) in combination with the two desorption/ionization methods, electrospray (ESI) and atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI), for the detection of antioxidants which are applied in lubricants. These experiments should form the base for future investigations of antioxidants in tribologically formed thin layers on the surface of frictional systems. Seventeen different antioxidants were selected out of the group of hindered phenolic and aromatic aminic compounds. Practically all antioxidants could be characterized by positive ion ESI- and AP-MALDI-ITMS, forming various types/species of molecular ions (e.g. [M]+*, [M+H]+, [M+Na]+ or [M-2H+H]+). A few compounds could be analyzed by negative ion ESI-MS, too, but none by negative ion AP-MALDI-MS. The influence of target materials in AP-MALDI-MS (gold- and titanium nitride (TiN)-covered stainless steel, micro-diamond-covered hard metal, hand-polished and sand-blasted stainless steel targets) with respect to the molecular ion intensity and type of molecular ion of two selected antioxidants was evaluated. The surface properties are of particular interest because in friction tests different materials with different surface characteristics are used. However, the MS results indicate that optimal target surfaces have to be found for individual antioxidants in AP-MALDI-MS but in general smooth surfaces were superior to rough surfaces. Finally the gold-covered stainless steel MALDI target provided the best mass spectra and was selected for all the antioxidants investigated.

CID of singly charged antioxidants applied in lubricants by means of a 3D ion trap and a linear ion trap–Orbitrap mass spectrometer

The aim of this study was to investigate the fragmentation behavior induced by low-energy collision-induced dissociation (LE-CID) of four selected antioxidants applied in lubricants, by two different types of ion trap mass spectrometers: a three-dimensional ion trap (3D-IT) and a linear IT (LIT) Orbitrap MS. Two sterically hindered phenols and two aromatic amines were selected as model compounds representing different antioxidant classes and were characterized by positive-ion electrospray ionization (ESI) and LE-CID. Various types of molecular ions (e.g. [M](+•) , [M + H](+) , [M + NH(4) ](+) or [M + Na](+) ) were used as precursor ions generating a significant number of structurally relevant product ions. Furthermore, the phenolic compounds were analyzed by negative-ion ESI. For both IT types applied for fragmentation, the antioxidants exhibited the same unusual LE-CID behavior: (1) they formed stable radical product ions and (2) CC bond cleavages of aliphatic substituents were observed and their respective cleavage sites depended on the precursor ion selected. This fragmentation provided information on the type of structural isomer usually not obtainable for branched aliphatic substituents utilizing LE-CID. Comparing the two instruments, the main benefit of applying the LIT-Orbitrap was direct access to elemental composition of product ions enabling unambiguous interpretation of fragmentation trees not obtainable by the 3D-IT device (e.g. loss of isobaric neutrals). It should be emphasized that the types of product ions formed do not depend on the type of IT analyzer applied. For characterizing degradation products of antioxidants, the LIT-Orbitrap hybrid system, allowing the determination of accurate m/z values for product ions, is the method of choice.

2nd Combined Working Group and Management Committee Meeting of Urine and Kidney Proteomics COST Action 29–30 March 2009, Nafplio, Greece

EuroKUP (Urine and Kidney Proteomics; www.eurokup.org) is a COST (European Cooperation in the field of Scientific and Technical research: www.cost.esf.org Action fostering a multi‐disciplinary network of investigators from 25 countries and focusing on facilitating translational proteomic research in kidney diseases. Four Working Groups focusing respectively on defining clinically important research questions in kidney diseases, kidney tissue proteomics, urine proteomics and bioinformatics have been generated. The EuroKUP members had their second combined Working Group and Management Committee (MC) meeting in Nafplio, Greece from March 29 to 30, 2009. This report summarizes the main presentations, discussions and agreed action points during this meeting. These refer to the design of collaborative projects and clinical center networks for specific kidney diseases; establishment of guidelines for kidney tissue proteomics analysis by laser‐based imaging‐ and laser capture microdissection‐MS; development and characterization of a “standard” urine specimen to be used for assessment of platform capability and data comparability in clinical proteomics applications; definition of statistical requirements in biomarker discovery studies; and development of a specialized kidney and urine ontology. Various training activities are planned involving training schools on laser capture microdissection‐ and imaging‐MS, workshops on ontologies as well as short‐term travel grants for junior investigators.

Intact Cell/Spore Mass Spectrometry of Fusarium Macro Conidia for Fast Isolate and Species Differentiation

The focus of this paper is the development of an approach called intact cell mass spectrometry (ICMS) or intact spore mass spectrometry (ISMS) based on the technique matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for the rapid differentiation and identification of Fusarium species. Several parameters, which are known to affect the quality of IC mass spectra, have been investigated in detail by varying the MALDI matrix as well as the solvent system, in which the matrix has been dissolved, the solvent system for sample purification and the type of sample/MALDI matrix deposition technique. In the end characteristic as well as highly reproducible IC or IS mass spectra or peptide/protein fingerprints of three Fusarium species (F. cerealis, F. graminearum and F. poae) including 16 Fusarium isolates derived from different hosts and geographical locations have been obtained. Unscaled hierarchical cluster analysis based on ICMS data of eight selected Fusarium isolates of two species F. graminearum and F. poae revealed significant difference among the peptide/protein pattern of them. The results of the applied cluster analysis proved that, ICMS is a powerful approach for the rapid differentiation of Fusarium species. In addition, an on-target tryptic digestion was applied to Fusarium macro conidia spores to identify proteins using MALDI post source decay (PSD) fragment ion analysis. Two kinds of trypsin, namely bead-immobilized − to favor cleavage of surface-associated proteins − and non-immobilized trypsin were applied and compared. The results showed that the latter is more suitable for generating sequence tags by PSD fragment ion analysis.

The third Central and Eastern European Proteomic conference

The third Central and Eastern European Proteomic Conference was held at Hotel Benzcur, Budapest, Hungary, from the 6–9 October 2009. The meeting was the third in a series of proteomic conferences to be held in this region of Europe, with the key aim of strengthening the links with scientists from Central and Eastern Europe, as well as international groups worldwide. It was attended by more than 150 delegates from various countries and many proteomic topics, including biomarker discovery, post-translational modifications, clinical proteomics, as well as new proteomic technologies, which may facilitate future progress, were discussed over the 3 days.

In‐chain neutral hydrocarbon loss from crocin apocarotenoid ester glycosides and the crocetin aglycon (Crocus sativus L.) by ESI‐MSn (n = 2, 3)

The stigmas of Crocus sativus L. have been used as spice and colorant agent (i.e. saffron) for more than 4000 years. For an updated structural investigation of the aglycon present in the glycosylated crocetin apocarotenoids (i.e. crocins), seven representative derivatives ranging from one up to five glucosyl-residues with a maximum number of three monosaccharides per glycosylation site (glucose, gentiobiose, gentiotriose and neapolitanose) were isolated and purified by high-performance liquid chromatography. The compounds selected for further mass spectrometric investigation include glucosyl-, bis-glucosyl-, gentiobiosyl-, gentiobiosyl-glucosyl-, bis-gentiobiosyl-, gentiobiosyl-gentiotriosyl- and gentiobiosyl-neapolitanosyl-crocetin. Electrospray ionization in combination with low-energy collision-induced dissociation/tandem mass spectrometry of sodiated crocin precursor ions utilizing either a 3D-ion trap (MS(n) , n = 2, 3) or a QqTOF instrument, with the latter providing accurate mass determination with an accuracy of ±1-3 ppm or better at a resolution of 10,000 (full width at half maximum), was used. Major fragmentation pathways included loss of either one or two carbohydrate substituents leading to the sodiated aglycon without interglycosidic bond cleavage during in MS(2) -experiments. All sodiated precursor ions and major product ions were accompanied by a loss of 92 Da, which was elucidated as C7 H8 -loss from the aglycon by skeletal rearrangement via an eight-membered transition state as previously described for intact C40-carotenoids.

Nano-aerosol approach for characterization of proteins and viruses

This contribution presents the potential of an innovative approach for determination of molecular masses of high-mass biopolymers through the aerosol phase. Macromolecular ions were formed by means of a nano-electrospray ionisation. The multiply charged species were charge-reduced to yield neutral, or singly charged airborne particles. Subsequently the so obtained aerosols were size separated according to their electrophoretic mobility in air using a nano-differential mobility analyzer. The particles were then detected by means of a condensation particle counter. The mobility diameters of well-defined proteins were determined and linked with their molecular weights in the range from 3.5 - 2000 kDa showing a correlation coefficient of 0.999. This calibration relationship allowed then the determination of large biocomplexes with a mass accuracy of the order of 5% including supramolecular complexes such as viruses. We investigated the stability of various noncovalent protein complexes as a function of pH. The study on the human rhinoviruses demonstated the capability of the used experimental system to measure the size of the intact infectious virus (HRV2) and its partial thermal dissociation. This research can be viewed as a first documentation of observation of stability of non-covalent complexes and of a real-time virus characterization using nanoaerosol measuring technique.