Time-of-flight Secondary Ion Mass Spectrometry Instrument Research Articles

Using ToF-SIMS analyses for analysing individual oil inclusions of different fluorescence colours in a single quartz crystal from the Barrandian (Czech Republic)

The fluorescence colour and molecular signature of oil inclusions can provide precious information on the thermal maturity of inclusion oils and the fluid migration history of basins. Here we show how molecular mass spectrometric analyses in combination with fluorescence microscopy can be used to reveal heterogeneities in the chemical compositions of oil inclusions within a micrometer sized quartz crystal. We used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to extract and directly analyse the molecular content of two yellow and two white-blue fluorescing oil inclusions in a single quartz crystal from the Barrandian Basin (Czech Republic). The cyclic ion species detected primarily in the yellow fluorescing oil inclusions likely originate from steranes, hopanes, and other tricyclic and tetracyclic terpanes, whereas these are less abundant in the white-blue fluorescing oil inclusions. Depth profiles of the fluid inclusions indicate that the white-blue fluorescing oil inclusions are emptied faster in the ToF-SIMS instrument, presumably due to a higher content of more volatile components than in the yellow fluorescing oil inclusions. The phenanthrene to dibenzothiophene ratio derived from ToF-SIMS of the four inclusion oils from the Barrandian Basin indicates marine clastic sediments as the source rocks for all the inclusion oils. The phenanthrene to alkylphenanthrene ratio derived from ToF-SIMS indicates no major difference in thermal maturity of the oil in the white-blue and yellow fluorescing oil inclusions. Instead, variation in the chemical content of the trapped oil induced by trapping fractionation may be the key control.

Multispectral optical imaging combinedin situwith XPS or ToFSIMS and principal component analysis

All X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) instruments have optical cameras to image the specimen under analysis, and often to image the sample holder as it enters the system too. These cameras help the user find the appropriate points for analysis of specimens. However they seldom give as good images as stand-alone bench optical microscopes, because of the limited geometry, source/analyser solid angle and ultra-high-vacuum (UHV) design compromises. This often means that the images displayed to the user necessarily have low contrast, low resolution and poor depth-of-field. To help identify the different regions of the samples present we have found it useful to perform multispectral imaging by illuminating the sample with narrow-wavelength-range light emitting diodes (LEDs). By taking an image under the illumination of these LEDs in turn, each at a successively longer wavelength, one can build up a set of registered images that contain more information than a simple Red–Green–Blue image under white-light illumination. We show that this type of multispectral imaging is easy and inexpensive to fit to common XPS and ToF-SIMS instruments, using LEDs that are widely available. In our system we typically use 14 LEDs including one emitting in the ultraviolet (so as to allow fluorescent imaging) and three in the near infra-red. The design considerations of this system are discussed in detail, including the design of the drive and control electronics, and three practical examples are presented where this multispectral imaging was extremely useful. Copyright © 2016 The Authors Surface and Interface Analysis Published by John Wiley & Sons Ltd.

アルゴンガスクラスターイオンビームと実用表面分析

Argon Gas Cluster Ion Beam (Ar-GCIB) is now widely spread in the field of practical surface analysis, such as X-ray photoelectron spectroscopy (XPS) and Time-of-Flight secondary ion mass spectrometry (TOF-SIMS), because of its unique sputtering effect of low chemical degradation for organic materials. GCIB provides the lateral sputtering effect and the high sputtering yield of which are never achieved by monotonic Ar ion beam on organic materials, so that the low chemical degradation of organic materials with high depth resolution and high sputtering rate could be achieved. Of course, a study of the GCIB sputtering phenomena with chemically reactive gasses, instead of Ar gas, for the advanced materials is one of the interesting things from an academic point of view. But the Ar-GCIB technique is expected to use for more practical applications, especially in the industrial field. In this paper, some practical applications of Ar-GCIB with recent XPS and TOF-SIMS instruments will be briefly introduced.

Time-of-flight secondary ion mass spectrometry imaging of biological samples with delayed extraction for high mass and high spatial resolutions.

RationaleIn Time‐of‐Flight Secondary Ion Mass Spectrometry (TOF‐SIMS), pulsed and focused primary ion beams enable mass spectrometry imaging, a method which is particularly useful to map various small molecules such as lipids at the surface of biological samples. When using TOF‐SIMS instruments, the focusing modes of the primary ion beam delivered by liquid metal ion guns can provide either a mass resolution of several thousand or a sub‐µm lateral resolution, but the combination of both is generally not possible.MethodsWith a TOF‐SIMS setup, a delayed extraction applied to secondary ions has been studied extensively on rat cerebellum sections in order to compensate for the effect of long primary ion bunches.ResultsThe use of a delayed extraction has been proven to be an efficient solution leading to unique features, i.e. a mass resolution up to 10000 at m/z 385.4 combined with a lateral resolution of about 400 nm. Simulations of ion trajectories confirm the experimental determination of optimal delayed extraction and allow understanding of the behavior of ions as a function of their mass‐to‐charge ratio.ConclusionsAlthough the use of a delayed extraction has been well known for many years and is very popular in MALDI, it is much less used in TOF‐SIMS. Its full characterization now enables secondary ion images to be recorded in a single run with a submicron spatial resolution and with a mass resolution of several thousand. This improvement is very useful when analyzing lipids on tissue sections, or rare, precious, or very small size samples. © 2015 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.

Abstract P6-07-05: Single-cell TOF-SIMS reveals that human breast cancer stem cells have significantly lower content of palmitoleic acid compared to their counterpart non-stem cancer cells

Abstract Background Distinguishing individual cancers according to their biochemical heterogeneity have provided much useful information to clinical site. Recently, the cancer stem cell (CSC) theory has been accepted as a concept that explains the mechanism of cancer recurrence and resistance to treatment. To characterize such particular cell populations in heterogeneous tissues, we conducted combination of fluorescence activated cell sorting (FACS) and time-of-flight secondary-ion mass spectrometry (TOF-SIMS) and applied the method to analyses of breast CSCs. TOF-SIMS, which enables to visualize the composition of molecules with mass over 100 Da that were obtained in specimen, has been employed to analyze surface of industrial materials and biomaterials. This method is thus suitable for performing single cell analysis of membranous lipids. Methods Breast cancer specimens surgically resected from two patients were enzymatically dispersed into cells. They were labeled with fluorescence-conjugated antibodies of CD45, CD44, and CD24. The cells of CD45-CD44+ CD24- were sorted as CSCs with FACS as well as CD45-CD44- CD24+ cells as non-stem cancer cells (NSCCs). TOF-SIMS analysis and fatty acid analysis was performed according to our previous study published in Surface and Interface Analysis (1). The surface of the sorted cells was analyzed by a PHI TRIFT V (ULVAC-PHI Inc., Kanagawa, Japan) TOF-SIMS instrument. Primary ion beam is irradiated to the surface of the samples and, secondary ions derived from samples are calculated by time-of-flight with the information of the place where the molecular ions were ejected. Negative secondary ions were obtained with a mass range of m/z 0–1850. Mass spectra were analyzed by WinCadenceN software (ULVAC-PHI Inc.) to obtain ion counts and ion images. Integrated ion intensities of FA were normalized using phosphoric acid intensity. The Welch’s t-test was used to compare the normalized ion counts with P-value < 0.05 taken as statistically significant. Results FACS analyses successfully collected CD45-/CD44+/CD24- CSCs and CD45-/CD44-/CD24+ non-stem cancer cells (NSCCs) in both two cases, which were corresponding to o.33% and 0.74% of all cells in case 1, and 0.14% and 1.14% in case 2. TOF-SIMS analyses visualized phosphoric acids and four fatty acid (FA) species in the sorted CSCs and NSCCs. These ions probably came from membranous phosphopolipids and they were uniformly detected from the locus where the cell attached. Integrated ion intensity of palmitoleic acids [FA(16:1)] of CSCs normalized by phosphoric acids signals were significantly decreased than that of CD45-/CD44-/CD24+ NSCCs as a counterpart. Therefore, our novel method successfully provided lipid composition analysis of individual cells classified with complicated combination of marker expressions in clinical specimens composed of heterogeneous cellular populations, and characterized lipid composition of CSCs. Reference 1. Nagata Y, Ishizaki I, Waki M, Ide Y, Hossen A, Ohnishi K, et al. Glutaraldehyde Fixation Method for Single-Cell Lipid Analysis by Time-of-Flight Secondary Ion-Mass Spectrometry. Surface and interface analysis : SIA. 2014:DOI: 10.1002/sia/5522. Citation Format: Yoshimi Ide, Michihiko Waki, Itsuko Ishizaki, Yasuyuki Nagata, Yumiko Taki, Yuko Hosokawa, Ryoichi Matsunuma, Hiroyuki Ogura, Norihiko Shiiya, Noriaki Sanada, Mitsutoshi Setou. Single-cell TOF-SIMS reveals that human breast cancer stem cells have significantly lower content of palmitoleic acid compared to their counterpart non-stem cancer cells [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-07-05.

Photocatalytic decomposition of methylene blue and 4-chlorophenol on nanocrystalline TiO 2 films under UV illumination: A ToF-SIMS study

The photocatalytic degradation of methylene blue and 4-chlorophenol on nanocrystalline TiO 2 (nc-TiO 2) under UV irradiation was investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Nanocrystalline TiO 2 films were prepared from suspensions containing TiO 2-crystallites of different average sizes, the smallest one being 12 nm. The organic substances (either methylene blue or 4-chlorophenol) were applied to these films. The specimens were studied in the pristine state and upon UV exposure. The UV illuminations were carried out both under atmospheric conditions and in situ under ultrahigh vacuum in the ToF-SIMS instrument. Distinct mass signals from the parent molecules and from fragment ions are observed for the as-prepared samples. Upon irradiation with UV light under atmospheric conditions, the surface composition is significantly changed, an observation ascribed to photocatalytic reactions induced by UV photons: the parent molecule signals are strongly diminished whereas fragmentation products are identified to be present at the TiO 2 surfaces. UV irradiations carried out under different vacuum conditions in the ToF instrument (ultrahigh vacuum, air or oxygen adsorption) indicate that varying ambient conditions may influence the photocatalytic reaction on the nanocrystalline TiO 2 films.

Analysis of Poly(amino acids) by Static Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

This study presents the static time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra of 15 poly(amino acids), solvent or spin cast onto either mica or silicon substrates. These poly(amino acid) spectra are useful for interpreting the complex static TOF-SIMS spectra obtained from adsorbed protein films and peptide-functionalized surfaces. Previous studies have reported poly(amino acid) spectra acquired with a quadrupole SIMS instrument. The spectra obtained with a TOF-SIMS instrument in this study have significantly higher sensitivity and mass resolution, which are essential for producing good, high-quality reference spectra.