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Traditional isotope sclerochronology employing isotope ratio mass spectrometry has been used for decades to determine the periodicity of growth increment formation in marine organisms with accretionary growth. Despite its well-demonstrated capabilities, it is not without limitation. The most significant of these being the volume of carbonate powder required for analysis with conventional drill-sampling techniques, which limit sampling to early in ontogeny when growth is fast or to species that reach relatively large sizes. In species like Astarte borealis (Schumacher, 1817), a common component of Arctic boreal seas, traditional methods of increment analysis are difficult, because the species is typically long-lived, slow growing, and forms extremely narrowly spaced growth increments. Here, we use Secondary Ion Mass Spectrometry (SIMS) to analyze [delta].sup.18O in 10-[mu]m-diameter spots and resolve the seasonal timing of growth increment formation in Astarte borealis in the southeastern Baltic Sea. In the individaul sampled here, dark growth increments can form in either the fall, winter, or spring. Furthermore, growth increment data from two populations (RFP3S = 54.7967° N, 12.38787° E; WA = 54.86775° N, 14.09832° E) indicate that in the Baltic Sea, A. borealis is moderately long-lived (at least 43 years) and slow growing (von Bertalanffy k values 0.08 and 0.06). Our results demonstrate the potential of A. borealis to be a recorder of Baltic Sea seasonality over the past century using both live- and dead-collected shells, and also the ability of SIMS analysis to broaden the spectrum of bivalves used in sclerocrhonological work., Author(s): David K. Moss [sup.1] , Donna Surge [sup.2] , Michael L. Zettler [sup.3] , Ian J. Orland [sup.4] [sup.5] , Alex Burnette [sup.2] , Abby Fancher [sup.2] Author Affiliations: [...]

Model samples of aqueous solutions containing iron(II/III) salts have been studied by secondary-ion mass spectrometry. Mass spectra of the samples containing ferrous and ferric ions have been compared. The possibility of using secondary-ion mass spectrometry for the analysis of rain precipitations and samples of atmospheric aerosols has been considered. Keywords: secondary-ion mass spectrometry, aqueous solutions of Fe(II)/Fe(III) DOI: 10.1134/S1061934813050122, In the previous work on the problem of the diagnostics of the composition of rain precipitations and aerosol species we have shown a possibility of using secondary-ion mass spectrometry (SIMS) [...]

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) enables chemically imaging the distributions of various lipid species in model membranes. However, discriminating the TOF-SIMS data of structurally similar lipids is very difficult because the high intensity, low mass fragment ions needed to achieve submicrometer lateral resolution are common to multiple lipid species. Here, we demonstrate that principal component analysis (PCA) can discriminate the TOF-SIMS spectra of four unlabeled saturated phosphatidylcholine species, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) according to variations in the intensities of their low mass fragment ions (m/z [less than or equal to] 200). PCA of TOF-SIMS images of phase-separated DSPC/DLPC and DPPC/DLPC membranes enabled visualizing the distributions of each phosphatidyicholine species with higher contrast and specificity than that of individual TOF-SIMS ion images. Comparison of the principal component (PC) scores images to atomic force microscopy (AFM) images acquired at the same membrane location before TOF-SIMS analysis confirmed that the PC scores images reveal the phase-separated membrane domains. The lipid composition within these domains was identified by projection of their TOF-SIMS spectra onto PC models developed using pure lipid standards. This approach may enable the identification and chemical imaging of structurally similar lipid species within more complex membranes. 10.1021/ac101640c

On the morning of July 16, 1945, the first atomic bomb was exploded in New Mexico on the White Sands Proving Ground. The device was a plutonium implosion device similar to the device that destroyed Nagasaki, Japan, on August 9 of that same year. Recently, with the enactment of US public law 111-140, the 'Nuclear Forensics and Attribution Act,' scientists in the government and academia have been able, in earnest, to consider what type of forensic-style information may be obtained after a nuclear detonation. To conduct a robust attribution process for an exploded device placed by a nonstate actor, forensic analysis must yield information about not only the nuclear material in the device but about other materials that went into its construction. We have performed an investigation of glassed ground debris from the first nuclear test showing correlations among multiple analytical techniques. Surprisingly, there is strong evidence, obtainable only through microanalysis, that secondary materials used in the device can be identified and positively associated with the nuclear material. secondary ion mass spectrometry | autoradiography | electron probe microanalysis | plutonium | trinitite doi/ 10.1073/pnas.1010631107

Although the benefits of decreased sample temperature for the molecular profiling of organic materials with time-of-flight secondary ion mass spectrometry (TOF-SIMS) have been established, the mechanism behind spectral changes observed at low temperature, particularly increased protonated molecular ion [(M + H).sup.+] yields, have not been examined in detail. We have developed a procedure to investigate these effects by monitoring secondary ion yields under sustained primary ion bombardment as the sample temperature is cooled from room temperature down to 80 K. Examination of biomaterlals such as an amino acid (arginine), a polypeptide (Gly-Gly-Tyr-Arg), a lipid (1,2 dipalmitoyl-sn-glycero-3 phosphatidylcholine), and a drug molecule (cyclosporine A) each provide evidence of ion yield enhancement at 80 K under either 20 keV [C.sub.60.sup.+] or 20 keV [Au.sub.3.sup.+] bombardment. For example, arginine shows a 2-fold increase in the steady-state intensity for the [(M + H).sup.+] ion at 80 K compared to the steady state at 300 K. It is shown that there is a correlation between the yield enhancement and a reduction in the damage cross section, which for arginine under 20 keV [Au.sub.3.sup.+] bombardment decreases from 5.0 [+ or -]0.4 x [10.sup.-14] [cm.sup.2] at 300 K to 2.0 [+ or -] 0.3 x [10.sup.-14] [cm.sup.2] at 80 K. The role of water as the facilitator for this reduction is explored through the use of [H.sub.2]O and [D.sub.2]O dosing experiments at 80 K. 10.1021/ac101746h

The application of surface analytical techniques such as time-of-flight secondary ion mass spectrometry (ToFSIMS) and X-ray photoelectron spectroscopy (XPS) is explored as a means of differentiating between composition C4 plastic explosives (C-4). Three different C-4 samples including U.S. military grade C-4, commercial C-4 (also from the United States), and C-4 from England (PE-4) were obtained and analyzed using both ToF-SIMS and XPS. ToF-SIMS was able to successfully discriminate between different C-4 samples with the aid of principal component analysis, a multivariate statistical analysis approach often used to reduce the dimensionality of complex data. ToF-SIMS imaging was also used to obtain information about the spatial distribution of the various additives contained within the samples. The results indicated that the samples could potentially be characterized by their 2-D chemical and morphological structure, which varied from sample to sample. XPS analysis also showed significant variation between samples, with changes in the atomic concentrations, as well as changes in the shapes of the high-resolution C Is and O 1s spectra. These results clearly demonstrate the feasibility of utilizing both ToF-SIMS and XPS as tools for the direct characterization and differentiation of C-4 samples for forensic applications. 10.1021/ac101116r

An in situ freeze fracture device featuring a spring-loaded trap system has been designed and characterized for time of flight secondary ion mass spectrometry (TOF SIMS) analysis of single cells. The device employs the sandwich assembly, which is typically used in freeze fracture TOF SIMS experiments to prepare frozen, hydrated cells for high-resolution SIMS imaging. The addition of the spring-loaded trap system to the sandwich assembly offers two advances to this sample preparation method. First, mechanizing the fracture by adding a spring standardizes each fracture by removing the need to manually remove the top of the sandwich assembly with a cryogenically cooled knife. A second advance is brought about because the top of the sandwich is not discarded after the sandwich assembly has been fractured. This results in two imaging surfaces effectively doubling the sample size and providing the unique ability to image both sections of a cell bifurcated by the fracture. Here, we report TOF SIMS analysis of freeze fractured rat pheochromocytoma (PC12) cells using a Bi cluster ion source. This work exhibits the ability to obtain single cell chemical images with subcellular lateral resolution from cells preserved in an ice matrix. In addition to preserving the cells, the signal from lipid fragment ions rarely identified in single cells are better observed in the freeze-fractured samples for these experiments. Furthermore, using the accepted argument that [K.sup.+] signal indicates a cell that has been fractured though the cytoplasm, we have also identified different fracture planes of cells over the surface. Coupling a mechanized freeze fracture device to high-resolution cluster SIMS imaging will provide the sensitivity and resolution as well as the number of trials required to carry out biologically relevant SIMS experiments. 10.1021/ac101243b

Intracellular magnetite crystal formation by magnetotactic bacteria has emerged as a powerful model for investigating the cellular and molecular mechanisms of biomineralization, a process common to all branches of life. Although magnetotactic bacteria are phylogenetically diverse and their crystals morphologically diverse, studies to date have focused on a few, closely related species with similar crystal habits. Here, we investigate the process of magnetite biomineralization in Desulfovibrio magneticus sp. RS1, the only reported species of cultured magnetotactic bacteria that is outside of the [alpha]-Proteobacteria and that forms bullet-shaped crystals. Using a variety of high-resolution imaging and analytical tools, we show that RS-1 cells form amorphous, non-crystalline granules containing iron and phosphorus before forming magnetite crystals. Using NanoSIMS (dynamic secondary ion mass spectroscopy), we show that the iron-phosphorus granules and the magnetite crystals are likely formed through separate cellular processes. Analysis of the cellular ultrastructure of RS-1 using cryo-ultramicrotomy, cryo-electron tomography, and tomography of ultrathin sections reveals that the magnetite crystals are not surrounded by membranes but that the iron-phosphorus granules are surrounded by membranous compartments. The varied cellular paths for the formation of these two minerals lead us to suggest that the iron-phosphorus granules constitute a distinct bacterial organelle. bacterial organelle | biomineralization | magnetotactic bacteria | dynamic secondary ion mass spectroscopy | magnetite doi/10.1073/pnas.1001290107

Room temperature ionic liquids (ILs) have many applications including as matrices in MALDI. We wished to investigate the efficacy of ILs as matrices in time-of-flight secondary ion mass spectrometry and in mass spectrometric imaging (MS imaging). Two ILs derived from [alpha]-cyano-4-hydroxycinnamic acid (CHCA) were synthesized and tested using phospholipids, cholesterol, and peptides. The molecular ion intensifies of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), cholesterol, and bradykinin were greatly increased using IL matrices. Further, detection limits were also improved: for DPPC and DPPE detection, limits were at least 2 orders of magnitude better using IL matrices. However, these IL matrices were not effective for the enhancement of angiotensin I ions. The data also indicate that IL matrices are suitable for imaging MS. The IL matrices did not cause changes to the sample surface via matrix crystallization or other processes; no 'hot spots' were observed in the mass spectra. As a demonstration, an onionskin membrane was imaged. In the matrix-enhanced MS images, ions characteristic of proteins and other biomolecules were observed which could not otherwise be observed. Clearly ionic liquids deserve further investigation in SIMS and MS imaging. 10.1021/ac100133c

Supramolecular polymeric materials are of increasing interest for the use as drug delivery carriers. A thorough insight in the biocompatibility and the degradation of these materials in vivo are of fundamental importance to further their development and application in medical practice. Molecular imaging techniques are powerful tools that enable the elucidation of molecular distributions in and around such polymer implants. A supramolecular polymeric hydrogel was implanted under the renal capsule to study its biocompatibility with TOF-SIMS. This results in a molecular cartography of the polymer implant combined with the cellular signature of the implantation environment. In this experiment, molecular signals are observed from cells that are involved in the biological response to the implant, e.g., macrophages. These molecular signatures are compared with macrophage standards cultured in different polarization environments. On the basis of this comparison, information can be acquired on the various macrophage differentiations that are connected to different stages in the foreign body response. Mass spectrometric imaging techniques offer the opportunity to visualize different histological phenomena in a single experiment without the need for specific immunohistochemical markers. Cellular infiltration into the polymer is visualized, offering a clear view on both biological and polymer features in a single imaging experiment. 10.1021/ac100837n

This study assesses the capability of high-resolution surface analytical tools to distinguish immobilized antibody orientations on patterned surfaces designed for antibody affinity capture. High-fidelity, side-by-side copatterning of protein A (antibody Fc domain affinity reagent) and fluorescein (antibody Fab domain hapten) was achieved photolithographically on commercial amine-reactive hydrogel polymer surfaces. This was verified from fuorescence imaging using fluorescently labeled protein A and intrinsic fluorescence from fluorescein. Subsequently, dye-labeled murine antifluorescein antibody (4-4-20) and antibody Fab and Fc fragments were immobilized from solution onto respective protein A- and fluorescein- copatterned or control surfaces using antibody--ligand affinity interactions. Fluorescence assays support specific immobilization to fluorescein hapten- and protein A-patterned regions through antigen--antibody recognition and natural protein A--Fc domain interactions, respectively. Affinity-based antibody immobilization on the two different copatterned surfaces generated side-by-side full antibody 'heads-up' and 'tails-up' oriented surface patterns. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis, sensitive to chemical information from the top 2 to 3 nm of the surface, provided ion-specific images of these antibody patterned regions, imaging and distinguishing characteristic ions from amino acids enriched in Fab domains for antibodies oriented in 'heads-up' regions, and ions from amino acids enriched in Fc domains for antibodies oriented in 'tails-up' regions. Principal component analysis (PCA) improved the distinct TOF-SIMS amino acid compositional and ion-specific surface mapping sensitivity for each 'heads-up' versus 'tails-up' patterned region. Characteristic Fab and Fc fragment immobilized patterns served as controls. This provides first demonstration of pattern-specific, antibody orientation-dependent surface maps based on antibody domain- and structure-specific compositional differences by TOF-SIMS analysis. Since antibody immobilization and orientation are critical to many technologies, orientation characterization using TOF-SIMS could be very useful and convenient for immobilization quality control and understanding methods for improving the performance of antibody-based surface capture assays. 10.1021/ac902964q

In this article, we addressed the applicability of time-of-flight secondary ion mass spectrometry (TOF-SIMS) to examine the effects of molecular weight and of flexible-segment length on the polymer chain arrangement at the folding surfaces of the lamellae. Poly(bisphenol A--etheralkane) (Cn) contains both rigid aromatic and flexible aliphatic C[H.sub.2] segments. The number of C[H.sub.2] units per flexible segment, n, varies from 8 to 12. Principal component analysis (PCA) of TOF-SIMS data revealed the chemical and structural variations of the folding surfaces of these polymers and identified the ion peaks contributing to these variations. We highlighted the discriminating power of PCA to distinguish the structural conformations of the amorphous and flat-on lamellar surfaces of these polymers. PCA loadings analyses showed that relatively more flexible structures were deposited on the folding surfaces when the flexible-segment length increased from 8 to 10 C[H.sub.2] units. The concentration of short loops at folding surfaces and the disorder of folding surfaces increased when the molecular weight increased. All these results led us to conclude that TOF-SIMS has great potential for probing the chemical composition of the folding surfaces of polymers. 10.1021/ac902280h

A detailed chemical and structural understanding of pre-enzymatic processing of lignocellulosic materials (LCMs) is a key objective in the development of renewable energy. Efficient rendering of biomass components into fermentable substrates for conversion into biofuel feedstocks would benefit greatly from the development of new technologies to provide high-quality, spatially resolved chemical information about LCMs during the various processing states. In an effort to realize this important goal, spatially correlated confocal Raman and mass spectrometric images allow the extraction of three-dimensional information from the perennial grass, Miscanthus x giganteus. An optical microscopy-based landmark registry scheme was developed that allows samples to be transferred between laboratories at different institutions, while retaining the capability to access the same physical regions of the samples. Subsequent to higher resolution imaging via confocal Raman microscopy and secondary ion mass spectrometry (SIMS), laser desorption-ionization mass spectrometry was used to place these regions within the overall sample architecture. Excellent sample registry was evident in the highly correlated Raman and SIMS images. In addition, the correlation of vibrational Raman scattering with mass spectra from specific spatial locations allowed confirmation of the assignment of intracellular globular structures to hemicellulose-rich lignin complexes, an assignment which could only be made tentatively from either image alone. 10.1021/ac100026r

Li-rich zincostaurolite occurs as millimeter-long crystals at the marble footwall of a meta-karstbauxite on eastern Samos. The Samos rocks have been metamorphosed during an early Alpine high-P, low-T metamorphism (M1) followed by a late Alpine greenschist-grade overprint (M2). Textures and mineral chemistry indicate that staurolite formed from gahnite, cookeite, and pyrophyllite during the early M1 stage. Staurolite crystals show growth zoning with cores enriched in Zn. Concentrations of Fe, Mg, Co, and, to a minor extent, Li increase toward the rims. Hydrogen concentrations were analyzed by SIMS. They are significantly higher in cores (up to 5.97 atoms H per 48 O) compared to rims (3.9 to 4.5 atoms H) and clearly negatively correlated with A1. Synchroton-light polarized FTIR spectra on oriented FIB-prepared foils show the same zonation effect, the absolute hydrogen concentrations being systematically lower by about 25%. The discrepancy is caused by sub-micrometer scale hydrogen loss at the crystal surface during FIB-thinning. This staurolite is unique as from the three available hydrogen sites the H3 site has the highest occupation ever observed, whereas the H2 site is not occupied. This is probably due to the high Li content. The zonation in hydrogen is interpreted as reflecting the two-stage growth. M1-staurolite that formed a low T of about 400-450[degrees]C and high P of >1.5 GPa incorporated nearly the maximum amount of hydrogen allowed by the staurolite structure (6 H pfu) and was subsequently overgrown and marginally replaced during the M2 stage by less hydrous, Fe-Co richer staurolite. Hydrogen zoning in staurolite is facilitated by the sensitivity of its structure to changing P-T conditions. Water in staurolite is maximized at high P and low T. Cores of staurolite from Samos represent the most hydrous staurolite compositions reported to date. Keywords: Staurolite, hydrogen zoning, SIMS, FTIR, Metabauxite

Mass spectrometry imaging has been used to map liver biopsies of several patients suffering from nonalcoholic fatty liver disease. This steatosis is characterized by an accumulation of triacylglycerols and diacylglycerols in the liver. Using time-of-flight-secondary ion mass spectrometry (TOF-SIMS) with a bismuth cluster ion source, it has been possible to map lipids in situ at the micrometer scale and to simultaneously characterize their molecular distribution on liver sections. Accumulation of triacylglycerols, diacylgiycerols, monoacylglycerols, fatty acids, with the apparition of myristic acid, together with a dramatic depletion of vitamin E and a selective macrovacuolar localization of cholesterol are observed in steatosis areas of fatty livers compared to control livers. These ion species are concentrated in small vesicles having a size of a few micrometers. Moreover, very fine differences in lipid localizations, depending on alkyl acid chain lengths of diacylglycerols and fatty acids, have been found after careful scrutiny of the ion images. Finally, TOF-SIMS has revealed lipid zonation in the normal human liver and accumulation of very similar lipids to those detected in areas of the fatty livers, which are not characterized as steatotic ones by the histological control performed on serial tissue sections.

Explosive volcanic eruptions may be triggered by processes in the conduit, including P-T variations, volatile loss, and crystal growth. These unobserved processes may be inferred via textural and chemical examination of eruptive products. Juvenile clasts were examined from vulcanian explosions of the Soufriere Hills volcano. Here we show that secondary ion mass spectrometry (SIMS) depth profiling into plagioclase phenocrysts provides a nearly continuous record of magma ascent from chamber to surface via high-resolution (~10 nm) chemical profiles of decompression-induced crystal growth. Changes in lithium concentration allow quantification of crystal growth rates, which range from 2 x [10.sup.-8] mm/s to 7 x [10.sup.-8] mm/s. Anorthite variations suggest conduit temperature increases of 50 to 100[degrees]C, assuming contemporaneous overpressures approaching 20 MPa. These data demonstrate a new means of constraining conduit conditions preceding explosive volcanic eruptions.

Silver nanoparticles (NPs) of ~5 nm diameter deposited in a single layer on glycine were examined with cluster secondary ion mass spectrometry (SIMS) in the event-by-event bombardment-detection mode. The projectiles used were [Au.sub.3.sup.+], [C.sub.60.sup.+], and [Au.sub.400.sup.4+] with impact energies of 34, 26, and 136 keV, respectively. The highest secondary ion yields were obtained with [Au.sub.400.sub.4+]. The method presented can test single or multilayer organization and determine surface coverage. NPs are identified one-by-one for chemical composition. Chemical and physical information in a nonimaging mode was resolved at ~10 nm. Grazing vs direct impacts on NPs were identified and quantified. NP fragmentation from direct impacts with [Au.sub.400.sub.4+] and [C.sub.60.sup.+]was observed for the first time.

[C.sub.60.sup.n+] ions have been shown to be extremely successful for SIMS depth profiling of a wide range of organic materials, causing significantly less degradation of the molecular information than more traditional primary ions. This work focuses on examining the definition of the interface in a [C.sub.60.sup.n+] SIMS depth profile for an organic overlayer on a wafer substrate. First it investigates the optimum method to define the organic/ inorganic interface position. Variations of up to 8 nm in the interface position can arise from different definitions of the interface position in the samples investigated here. Second, it looks into the reasons behind large interfacial widths, i.e., poor depth resolution, seen in [C.sub.60.sup.n+] depth profiling. This work confirms that, for Irganox 1010 deposited on a wafer, the depth resolution at the Irganox 1010/substrate interface is directly correlated to the roughening of material.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) can be utilized to map the distribution of various molecules on a surface with submicrometer resolution. Much of its biological application has been in the study of membrane lipids, such as phospholipids and cholesterol. Cholesterol is a particularly interesting molecule due to its involvement in numerous biological processes. For many studies, the effectiveness of chemical mapping is limited by low signal intensity from various biomolecules. Because of the high energy nature of the SIMS ionization process, many molecules are identified by detection of characteristic fragments. Commonly, fragments of a molecule are identified using standard samples, and those fragments are used to map the location of the molecule. In this work, MS/MS data obtained from a prototype [C.sub.60.sup.+]/quadrupole time-of-flight mass spectrometer was used in conjunction with indium LMIG imaging to map previously unrecognized cholesterol fragments in single cells. A model system of J774 macrophages doped with cholesterol was used to show that these fragments are derived from cholesterol in cell imaging experiments. Examination of relative quantification experiments reveals that m/z 147 is the most specific diagnostic fragment and offers a 3-fold signal enhancement. These findings greatly increase the prospects for cholesterol mapping experiments in biological samples, particularly with single cell experiments. In addition, these findings demonstrate the wealth of information that is hidden in the traditional TOF-SIMS spectrum.

Secondary ionization mass spectrometry (SIMS) U/Pb dating of zircon has been applied to rocks of the Lewisian Complex of South Harris (Outer Hebrides, NW Scotland), yielding insights into the complex geological evolution of this region and enhancing our understanding of terranes in the Lewisian Gneiss Complex. Results show that tonalite--trondhjemite--granodiorite magmatism occurred in the Tarbert Terrane between c. 2850 and 2830 Ma, equivalent to similar rocks in other parts of the Outer Hebrides. Magmatism was accompanied or closely followed by high-grade metamorphism at c. 2830 Ma, the first reported occurrence of such an event at this time. These rocks were affected by a subsequent high-grade metamorphic event at c. 2730 Ma, which has correlatives both in the Outer Hebrides and in the mainland Lewisian Gruinard Terrane. These data suggest that the 'terranes' forming the Outer Hebrides and parts of the mainland Lewisian were once contiguous and were fragmented by post-2730 Ma events. The c. 1700-1660 Ma ages from felsic sheets and pegmatites within the Langavat Shear Zone may record the reassembly of these crustal fragments.

A model alkane molecule, triacontane, is used to assess the effects of condensed gold and silver nanoparticles on the molecular ion yields upon atomic ([Ga.sup.+] and [In.sup.+]) and polyatomic ([C.sub.60.sup.+] and [Bi.sub.3.sup.+]) ion bombardment in metalassisted secondary ion mass spectrometry (MetA-SIMS). Molecular films spin-coated on silicon were metallized using a sputter-coater system, in order to deposit controlled quantities of gold and silver on the surface (from 0 to 15 nm equivalent thickness). The effects of gold and silver islets condensed on triacontane are also compared to the situation of thin triacontane overlayers on metallic substrates (gold and silver). The results focus primarily on the measured yields of quasi-molecular ions, such as [(M - H).sup.+] and [(2M - 2H).sup.+], and metal-eationized molecules, such as [(M + Au).sup.+] and [(M + Ag).sup.+], as a function of the quantity of metal on the surface. They confirm the absence of a simple rule to explain the secondary ion yield improvement in MetA-SIMS. The behavior is strongly dependent on the specific projectile/metal couple used for the experiment. Under atomic bombardment ([Ga.sup.+], [In.sup.+]), the characteristic ion yields an increase with the gold dose up to ~6 nm equivalent thickness. The yield enhancement factor between gold-metaUized and pristine samples can be as large as ~70 (for [(M - H).sup.+] under [Ga.sup.+] bombardment; 10 nm of Au). In contrast, with cluster projectiles such as [Bi.sub.3.sup.+] and [C.sub.60.sup.+], the presence of gold and silver leads to a dramatic molecular ion yield decrease. Cluster projectiles prove to be beneficial for triacontane overlayers spin-coated on silicon or metal substrates (Au, Ag) but not in the situation of MetA-SIMS. The fundamental difference of behavior between atomic and cluster primary ions is tentatively explained by arguments involving the different energy deposition mechanisms of these projectiles. Our results also show that Au and Ag nanoparticles do not induce the same behavior in MetA-SIMS of triacontane. The microstructures of the metallized layers are also different. While metallic substrates provide higher yields than metal islet overlayers in the case of silver, whatever the projectile used, the situation is reversed with gold.

We present a quantitative, imaging technique based on nanometer-scale secondary ion mass spectrometry for mapping the 3D elemental distribution present in an individual micrometer-sized Bacillus spore. We use depth profile analysis to access the 3D compositional information of an intact spore without the additional sample preparation steps (fixation, embedding, and sectioning) typically used to access substructural information in biological samples. The method is designed to ensure sample integrity for forensic characterization of Bacillus spores. The minimal sample preparation/alteration required in this methodology helps to preserve sample integrity. Furthermore, the technique affords elemental distribution information at the individual spore level with nanometer-scale spatial resolution and high ([micro]g/g) analytical sensitivity. We use the technique to map the 3D elemental distribution present within Bacillus thuringiensis israelensis spores.

Iron containing-antigen bound specifically to antibody immobilized on a surface is analyzed by nanoscale secondary ion mass spectrometry (NanoSIMS). This technique is well adapted compared with X-ray photoelectron spectroscopy and energy dispersive spectroscopy, which do not allow the detection of iron. The obtained [Fe.sup.+] map gives a good representation of the antigen repartition on the surface. NanoSIMS analysis of competition experiments performed with albumin and iron-free antigen are in good accordance with results obtained by a classical fluorescence microscopy approach. These results underline the interest of imaging NanoSIMS as a label-free method, allowing the localization and quantitative analysis of antigen--antibody binding with better spatial resolution than imaging ellipsometry and SPR.

A label-free, activity-based assay of matrix metalloproteinase (MMP) and its inhibition was demonstrated on peptide-conjugated gold nanoparticles (AuNPs) with nonbiofouling poly(oligo(ethylene glycol) methacrylate) (pOEGMA) films using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Following surface-initiated atom-transfer radical polymerization of OEGMA on a Si/Si[O.sub.2] substrate, the MMP activity was determined by analyzing the cleaved peptide fragments using TOF-SIMS on the peptide-conjugated AuNPs. The use of nonbiofouling pOEGMA films in conjunction with AuNPs synergistically enhanced the sensitivity of assays for MMP activity and its inhibition in human serum. The detection sensitivity of MMP-7 in serum was as low as 20 ng [mL.sup.-1] (1 pmol [mL.sup.-1]), and the half-maximal inhibitory concentration ([IC.sub.50]) of minocycline, which is a MMP-7 inhibitor, was estimated to be 450 nM. It is anticipated that the developed system will be broadly useful for conducting activity-based assays of serum proteases, as well as for screening of their inhibitors, with high sensitivity in a high-throughput manner.

Ordinary kriging and inverse distance weighted (IDW) are two interpolation methods for spatial analysis of data and are commonly used to analyze macroscopic spatial data in the fields of remote sensing, geography, and geology. In this study, these two interpolation techniques were compared and used to analyze microscopic chemical images created from time of flight-secondary ion mass spectrometry images from a patterned polymer sample of fluorocarbon ([C.sub.x][F.sub.y]) and poly(aminopropyl siloxane) (APS, a.k.a, siloxane). Data was eliminated from the original high-resolution data set by successive random removal, and the image file was interpolated and reconstructed with a random subset of points using both methods. The statistical validity of the reconstructed image was determined by both standard geographic information system (GIS) validation statistics and evaluating the resolution across an image boundary using ASTM depth and image resolution methodology. The results show that both ordinary kriging and IDW techniques can be used to accurately reconstruct an image using substantially fewer sample points than the original data set. Ordinary kriging performed better than the IDW technique, resulting in fewer errors in predicted intensities and greater retention of original image features. The size of the data set required for the most accurate reconstruction of the original image is directly related to the autocorrelation present within the data set. When 10% of the original siloxane data set was used for an ordinary kriging interpolation, the resulting image still retained the characteristic gridlike pattern. The [C.sub.x][F.sub.y] data set exhibited stronger spatial correlation, resulting in reconstruction of the image with only 1% of the original data set. The removal of data points does result in a loss of image resolution; however, the resolution loss is not directly related to the percentage of sample points removed.

The detection of high-mass, nonstoichiometric, [Ga.sub.x][As.sub.y] and [In.sub.x][P.sub.y] secondary ion clusters using time-of-flight secondary ion mass spectrometry is reported for the first time. The [Ga.sub.x][As.sub.y] and [In.sub.x][P.sub.y] clusters are detected in both positive and negative ion spectra and extend to masses of at least 6000 dalton (Da). Consecutive clusters differ by the addition of one gallium (indium) atom. This leads to nonstoichiometric clusters at high mass (i.e., [Ga.sub.15] [As.sub.3] at 1270 Da) which are metastable above a critical mass. The relative secondary ion yields of high-mass [Ga.sub.x][As.sub.y] clusters detected using several primary ion sources ([Cs.sup.+], [Bi.sup.+], [Bi.sub.3.sup.+], [Bi.sub.3.sup.2+], [Bi.sub.5.sup.2+], [C.sub.60.sup.2+], and [C.sub.60.sup.2+]) are compared. The relative secondary ion yield of high-mass [Ga.sub.x][As.sub.y] clusters is significantly enhanced by the use of cluster primary ions and the best relative secondary ion yield is obtained using [Bi.sub.3.sup.+] primary ions. An application of the high-mass [Ga.sub.x][As.sub.y] clusters is presented, in which these clusters are utilized to distinguish between contaminant levels of Ga and bulk GaAs structure in a depth profile of a MnAs/GaAs heterojunction. These results illustrate improved analysis of inorganic materials using cluster primary ions and break the paradigm of stoichiometric secondary cluster ion formation for SIMS of inorganic compounds.

For immobilization of proteins onto surfaces in a specific and controlled manner, it is important to start with a well-defined surface that contains specific binding sites surrounded by a nonfouling background. For immobilizing hisfidine-tagged (his-tagged) proteins, surfaces containing nitrilotriacetic acid (NTA) headgroups and oligo(ethylene glycol) (OEG) moieties are a widely used model system. The surface composition, structure, and reactivity of mixed NTA/OEG self-assembled monolayers (SAMs) on Au substrates were characterized in detail using X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and surface plasmon resonance (SPR) biosensoring. XPS results for sequential adsorption of NTA thiols followed by OEG thiols showed that OEG molecules were incorporated into an incompletely formed NTA monolayer until a complete mixed SAM was formed. The surface concentration of NTA headgroups was estimated to be 0.9-1.3 molecule/[nm.sup.2] in the mixed NTA/OEG monolayers, compared to 1.9 molecule/[nm.sup.2] in pure NTA monolayers. Angle-dependent XPS indicated NTA headgroups were slightly reoriented toward an upright position after OEG incorporation, and polarization-dependent NEXAFS results indicated increased ordering of the alkane chains of the molecules. Nitrogen-containing and OEG-related secondary ion fragments from the TOF-SIMS experiments confirmed the presence of NTA headgroups and OEG moieties in the monolayers. A multivariate peak intensity ratio was developed for estimating the relative NTA concentration in the outermost (10 [Angstrom]) of the monolayers. SPR measurements of a his-tagged, humanized antilysozyme variable fragment (HuLys Fv) immobilized onto Ni(II)-treated mixed NTA/OEG and pure NTA monolayers demonstrated the reversible, site-specific immobilization of his-tagged HuLys Fv (108-205 ng/[cm.sup.2]) with dissociation rates ([k.sub.off]) between 1.0 x [10.sup.-4] and 2.1 x [10.sup.-5] [s.sup.-1], both depending on the NTA surface concentration and orientation. The monolayers without Ni(II) treatment exhibited low nonspecific adsorption of his-tagged HuLys Fv (

Imaging using time-of-flight secondary ion mass spectrometry (TOF-SIMS) with buckministerfullerene ([C.sub.60]) primary ions offers the possibility of mapping the chemical distribution of molecular species from biological surfaces. Here we demonstrate the capability of the technique to provide biomolecular information from the cell surface as well as from within the surface, as illustrated with the distribution of two antibiotics in Streptomyces coelicolor (a mycelial bacterium). Differential production of the two pigmented antibiotics under salt-stressed and normal conditions in submerged cultivations could be detected from the TOF-SIMS spectra of the bacteria, demonstrating the potential of the technique in studying microbial physiology. Although both the antibiotics were detected on the cell surface, sputter etching with [C.sub.60+] revealed the spectral features of only one of the antibiotics within the cells. Exploratory analysis of the images using principal component analysis assisted in analyzing the spectral information with respect to peak contributions and their spatial distributions. The technique allows the study of not only lateral but also the depthwise distribution of biomolecules, uniquely enabling exploration of the processes within biological systems with minimal system intervention and with little a priori biochemical knowledge of relevance.

A new method that can chemically discriminate the visually indistinguishable sapwood from heartwood in discolored woods is presented in this paper. Discriminating between sapwood and heartwood, which are normally recognized by color in cross sections of stems of tress, is important in dendrochronological dating, as well as in evaluating qualities of woods such as durability. In treering chronology, the felling date, which affects the construction date of architectures, can be estimated only in woods that have a recognizable sapwood/heartwood boundary. However, the felling date cannot be estimated in discolored woods because it has indistinguishable sapwood. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of specific chemical substances retained for approximately 1300 years after felling demonstrated the presence of sapwood in a discolored ancient architectural wood of Hinoki cypress (Chamaecyparis obtusa). Direct molecular mapping by TOF-SIMS clearly indicated that the specific substances, hinokinin, hinokiresinol, hinokione, and hinokiol, started to accumulate at the sapwood/heartwood boundary where only hinokinin was localized and retained predominantly in ray parenchyma cells. The result allowed the determination of the felling date of the discolored wood. TOF-SIMS has shown to be useful for investigating the distribution of minute amounts of chemical components in woods.

Cluster secondary ion mass spectrometry (cluster SIMS) employing an [SF.sub.5.sup.+] polyatomic primary ion sputter source in conjunction with a [Bi.sub.3.sup.+] analysis source was used to obtain three-dimensional molecular information in polymeric-based drug-eluting stent coatings. The formulations of the coatings varied from 0% to 50% (w/w) sirolimus drug in poly(lactic-co-glycolic acid) and were prepared on both MP35N metal alloy coupons and bare metal stents. All cluster SIMS depth profiles obtained indicated a drug-enriched surface region, followed by a drug-depletion region, and finally a constant bulk composition region, similar to previous data obtained in polymeric blend systems. The drug overlayer thickness was determined to increase with increasing sirolimus content. Sample temperature was determined to play an important role in the resulting depth profiles, where it was shown that the best profiles were obtained at low temperatures (-100 [degrees]C). At these temperatures, molecular signals typically remained constant through the entire depth of the film (~6.5 [micro]m) in some cases, as opposed to the typical 1/[micro]m-2/[micro]m depth limit, which is achievable at room temperature. The 3-D imaging capabilities of cluster SIMS were successfully demonstrated and indicated a significant amount of subsurface domain formation in the 25% and 50% sirolimus samples, but not in the 5% sample, which was homogeneous. These results clearly illustrate the utility of cluster SIMS for probing the 3-D structure in polymeric-based drug delivery devices.

Furanone compounds (fimbrolides) have attracted interest as antibacterial compounds for use in human health care, for instance, as an antibacterial coating for medical devices to combat device-centered infections. To ensure effectiveness for extended periods of time, they must be immobilized covalently onto a device surface; in this study, this was done via azide/nitrene chemistry and photochemical coupling. However, the detection and quantification of surface-immobilized small molecules such as fitranones presents a considerable analytical challenge, yet is necessary for optimization of coatings and reliable interpretation of biological responses. We have utilized the surface sensitivity and chemical specificity of time-of-flight secondary ion mass spectrometry (TOF-SIMS) to characterize each step of the grafting sequence. On account of the complexity of the data, principal component analysis (PCA) was used to interpret and compare spectra. The results demonstrate the utility of TOF-SIMS with PCA for the detection of the surface-grafted small molecules azidoaniline and a brominated furanone; imaging of the bromine ion peaks also enabled assessment of grafting uniformity. Thus, successful multilayer coating and furanone grafting was observed, and substantial and uniform coverage of furanone molecules on the surface. Even multiple grafting steps involving, in the present case, two low molecular weight compounds can readily be disentangled by PCA. The utility of TOF-SIMS analysis with PCA is particularly well illustrated in the present case by the grafting of the furanone molecules, which did not yield a singular unique peak in the positive ion mass spectra, whereas the collective spectral changes elucidated by PCA provided unambiguous verification of successful grafting of this low molecular weight compound.

Ambient inclusion trails (AIT) are enigmatic microtubular structures created by the migration of mineral crystals through a lithified substrate. The decomposition of organic material has been suggested as the driving force for the crystal migration, but has yet to be rigorously tested. AIT may hold potential as a biosignature for investigating early life on Earth if the associated organic material can be shown to be biological. This paper attempts to test the formation mechanism and biogenicity of AIT from the c. 3400 Ma Strelley Pool sandstone of Western Australia using NanoSIMS technology. In doing so, we demonstrate the unique ability of the NanoSIMS to combine sub-micron scale imaging with in situ chemical and isotopic data, thereby enhancing our ability to evaluate the biogenicity criteria for Archaean microstructures. Enrichments of a suite of major elements (C, N, P, S) and trace elements (Co, Fe, Ni, Zn), often associated with biological processes, are found within several AIT in this sandstone. C and N enrichments are most common along AIT margins, and correlate with depletions of Si, O, Ca and Mg, indicating that this material is indeed organic in nature. [[delta].sup.13]C values of this carbonaceous material average -26 [per thousand]. Petrographic observations show that some of the AIT occur in the centre of detrital sandstone grains where they were sealed from later fluid flow and therefore preserve primary Archaean (bio)geochemistry. In contrast, AIT found around the outer edges of sandstone grains may contain more recent organic material introduced by later fluid migration and are an unreliable biosignature. Using the petrographic and geochemical data a multi-stage model for AIT formation and subsequent diagenetic modification is proposed. The possible sources of the primary organic material are discussed and we conclude that the data are consistent with a biological origin for these AIT. An abiogenic origin is more difficult to sustain but cannot yet be completely excluded for AIT in general.

A new protocol is implemented to demonstrate the presence of blood in the patina of African art objects from Mali. Divided into three steps, the protocol first consists in demonstrating the presence of proteins and localizing them in the sample's cross sections using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and synchrotron-based infrared microspectrometry ([mu]FT-IR). In a second time, TOF-SIMS is used to investigate heme, which is a blood marker. If heme is missing, which could mean that it is too degraded to be detected, X-ray microfluorescence ([mu] XRF) and X-ray absorption near-edge microspectroscopy ([micro] XANES) are used to prove the presence of iron in the protein area and to get a fingerprint of its chemical environment. This permits us thus to demonstrate that iron is indeed linked with proteins and not with mineral phases of the sample. Coupled with the ritual context of the objects, this constitutes a proof of the use of blood. Thanks to this protocol, which has the major advantage of avoiding false positive results, the presence of blood has been demonstrated in seven out of the eight studied samples.

The advantages and drawbacks of using either monatomic or buckminsterfullerene primary ions for metal-assisted secondary ion mass spectrometry (MetA-SIMS) are investigated using a series of organic samples including additive molecules, polyolefins, and small peptides. Gold deposition is mostly performed by sputter-coating, and in some cases, the results are compared to those of thermal evaporation (already used in a previous article: Delcorte, A.; Medard, N.; Bertrand, P. Anal. Chem. 2002, 74, 4955). The microstructure of the gold-covered sample surfaces is assessed by scanning and transmission electron microscopies. The merits of the different sets of experimental conditions are established via the analysis of fragment and parent-like ion yields. For most of the analyzed samples, the highest yields of fragment and parent-like ions are already reached with the sole use of [C.sub.60.sup.+] projectiles. Metallization of the sample does not lead to a significant additional enhancement. For polyethylene and polypropylene, however, gold metallization associated with [Ga.sup.+]/[In.sup.+] projectiles appears to be the only way to observe large cationized, sample-specific chain segments (m/z ~ 1000-2000). A detailed study of the polypropylene mass spectra as a function of gold coverage shows that the dynamics of yield enhancement by metal nano-particles is strongly dependent on the choice of the projectile, e.g., a pronounced increase with [Ga.sup.+] and a slow decay with [C.sub.60.sup.+]. The cases of Irganox 1010, a polymer antioxidant, and leucine enkephalin, a small peptide, allow us to investigate the specific influence of the experimental conditions on the emission of parent-(like) ions such as [M.sup.+], [(M + Na).sup.+], and [(M + Au).sup.+]. The results show a dependence on both the type of sample and the considered secondary ion. Using theoretical and experimental arguments, the discussion identifies some of the mechanisms underlying the general trends observed in the results. Guidelines concerning the choice of the experimental conditions for MetA-SIMS are provided.

We demonstrate the effects of protein orientation and trehalose on a quantitative analysis of surface-immobilized proteins by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). As our model protein, streptavidin (SA) was quantitatively immobilized on a solid surface at different configurations by random or oriented immobilization and subsequently treated with trehalose. The resulting surface was analyzed by using TOF-SIMS and surface plasmon resonance (SPR) spectroscopy, where the secondary ion spectra from SA were compared with the surface density of the protein. In the case of oriented immobilization, the ion peak intensities measured by TOFS-IMS were correlated well with the SPR data, regardless of the presence of trehalose. Alternatively, trehalose significantly increased correlation between TOF-SIMS and SPR data for the randomly immobilized SA. It is likely that a trehalose-treated surface is less vulnerable to denaturation, thus leading to a reliable quantification of surface-immobilized proteins by TOF-SIMS. Our results show that TOF-SIMS can be used for understanding biophysical states such as orientation and denaturation of surface-immobilized proteins as well as for quantifying proteins within the field of biosensors and biochips.

A novel and practical technique for performing both parent and neutral loss (P&NL) monitoring experiments on a quadrupole ion trap mass spectrometer is presented. This technique is capable of performing scans analogous to the parent and neutral loss scans routinely applied on tandem-in-space instruments and allows for the screening of a sample to detect analytes of a specific compound class on a chromatographic time-scale. Acylcarnitines were chosen as the model compound class to demonstrate the analytical utility of P&NL monitoring because of their amenability to electrospray ionization (ESI), their unique and informative MS/MS fragmentation pattern, and their importance in biological functions. The [[M + H].sup.+] ions of all acylcarnitines dissociate to produce neutral losses of 59 and 161 amu and common product ions at m/z 60, 85, and 144. Both the neutral loss monitoring of 59 amu and the parent ion monitoring of m/z 85 are shown to be capable of identifying acylcarnitine [[M + H].sup.+] ions in a synthetic mixture and spiked pig plasma. The neutral loss monitoring of 59 amu is successful in detecting acylcarnitines in an unspiked pig plasma sample.

A 'top-down' protein separation and identification methodology makes use of ion parking approach to facilitate the gas-phase concentration and purification of precursor ions from a complex protein mixture. Dissociation of the ions using a quadrupole ion trap and matching up with the ion spectra database identify the proteins in the mixture.

We have developed and validated a method that uses liquid chromatography/electrospray ionization-mass spectrometry to quantify site-specific protein phosphorylation. The method uses selected ion monitoring to determine the chromatographic peak areas of specific tryptic peptides from the protein of interest. The extent of phosphorylation is determined from the ratio of the phosphopeptide peak area to the peak area of an unmodified reference peptide that acts as internal standard, correcting for variations in protein amounts and peptide recovery in the digest preparation procedure. As a result, we refer to this protocol as the native reference peptide method. Mole of phosphate at the selected site per mole of protein is obtained from this ratio, using calibration curves of synthetic peptides to determine relative responses. Our method begins with protein separation by SDS-PAGE and is carried out on amounts of peptide produced by an ingel digestion of single Coomassie blue-stained bands. To illustrate the utility of the method and provide validation, we used cardiac troponin I as analyte and monitored the time course of a protein kinase C [beta]II reaction. Those analyses appropriately demonstrate the time-dependent increase of phosphorylation at a PKC-preferred site, Ser44 in the peptide [sup.41][ISAS.sup.p][R.sup.45] and the concomitant consumption of the nonphosphorylated peptide. We believe that this method provides a novel tool to directly measure specific phosphorylation sites in proteins in different physiological states and expect that the method will be adaptable not only to a variety of samples types (i.e., culture cells, tissues, etc.) but to a variety of posttranslation modifications as well.

The first detailed study of the high-mass, unit-resolution mass spectra of acrylic polymers is reported. In the high-mass range all polymers show repeating patterns extending to ca. 3500 Da. Each pattern consists of a number of clusters which, in turn, consist of a series of individual spectral lines. The clusters are shown to be derived from neutral fragments of the polymer chain, each cationized with a silver ion. The clusters result from closely related species differing by degrees of unsaturation. Fragments observed arise from isolated events. Polymer chain scission can be rationalized by several simple mechanisms, to a first approximation involving mainchain fracture. The effect of the ester R group becomes more important with increasing chain length, as well as with the addition of rings and branching of the ester group. Detailed analysis of the structure of the clusters showed that at least four chemical species contribute to each cluster, corresponding to zero to three rings and/or double bonds., The derivation of new data regarding polymer fragmentation by time-of-flight secondary ion mass spectrometry (TOP-SIMS) is discussed. The high-mass, unit resolution mass spectra of poly(alkyl methacrylates) is used in the TOP-SIMS experiments for the development of suggested chain decomposition and structural processes. The presence of chemical species that affect the polymer chain scission of the polyethylene was established.

The use of continuousflow fast atom bombardment (CF-FAB) to ionize the sample for tandem mass spectrometry (MS/MS) reduces the background ion current in the sequencing of peptides at the picomole level, thus improving the signal/noise ratio 50 to 100times. The required amount of analyte drops by 25-75%. When paired with array detection (AD), the method registers a detection limit of 900 fmol, well below that of the sequential Edman method. Moreover, CF-FAB-AD-MS/MS can analyze peptide samples at levels where conventional FAB methods cannot yield detectable ions.