New Mass Spectrometry Technology

Mass Spectrometry of Ultrahigh-Mass Bioparticles [ 下載 PDF ]

Zhiqiang Zhu, Huan-Cheng Chang

Measuring masses of ultrahigh-mass bioparticles (m > 1 MDa) has been a challenge in the field of mass spectrometry. Combining the techniques of laser-induced acoustic desorption, charge-sensitive detection, and quadrupole ion traps as the mass analyzer, we have successfully measured the masses of intact bioparticles such as viruses, bacteria, and cells in the gas phase for the first time. These particles have sizes ranging from ~100 nm to ~10 µm, with masses spanning up to 6 orders of magnitude (10⁸–10¹⁴ Da). Different from conventional mass spectrometry, we measured the masses of these bioparticles individually.

Mass Spectrometry in Proteome Application [ 下載 PDF ]

Chin-Jen Wu, Shih-Shin Liang, Shu-Hui Chen

Since the discovery of electrospray ionization (ESI) and matrix assisted laser desorption and ionization (MALDI), mass spectrometry (MS) has become the major player in proteomics analysis. In recent years, the advances in MS instrumentation and related techniques have greatly enhanced the capability and robustness of MS-based platform for proteomics. In this article, we will introduce the principles of MS and related methodologies for applications in proteomics analysis. The application fields in proteomics will include database assisted protein identification, protein post translational modifications and protein quantifications.

Analysis of Modified DNA and Proteins by Mass Spectrometry as Disease Biomarkers [ 下載 PDF ]

Hauh-Jyun Candy Chen

Modifications of DNA by endogenous or environmental reactive species could lead to mutation during DNA replication, which is the initiation step of carcinogenesis. Thus, accurate quantification of modified DNA products has been used for cancer risk assessment and for strategies in cancer prevention. Post-translational modifications of proteins by reactive species could cause functional alteration of proteins due to structural change. In this article, analyses of the ultra-trace amounts of the DNA and protein modification products by various mass spectrometric methods are reviewed.

Application of Environmental Mass Spectrometry in Emerging Contaminants Analysis [ 下載 PDF ]

Wang-Hsien Ding, Hsin-Chang Chen

In this overview article, we discussed the progress of liquid chromatography/mass spectrometry (LC/MS) and LCtandem MS (LC/MS/MS) in environmental analysis. The article covered challenges and achievements that occurred last couple years for emerging contaminants analysis, especially focusing on brominated flame retardants, perfluorinated surfactants, perchlorate, endocrine disrupting compounds (EDCs) and hormones and nanomaterials. LC/MS coupled with atmospheric pressure ionizations (i.e., electrospray ionization and atmospheric pressure photoionization) continued to dominate the new methods developed and the use of tandem MS technique has become commonplace for quantitative environmental analysis. The applications of newly developed hybrid mass spectrometric techniques, such as quadrupole time-of-flight MS and quadrupole linear-ion-trap MS, for pharmaceutical residues analysis in complex matrices were also introduced.

Identification of Pathogens in Clinical Samples — Application of Capillary Electrophoresis-Selective Tandem Mass Spectrometry [ 下載 PDF ]

Cheng-Ying Lin, Yen-Peng Ho

Analysis of microbial mixtures in complex systems, such as clinical samples, using mass spectrometry can be challenging because the specimens may contain mixtures of several pathogens or both pathogens and nonpathogens. We have successfully applied capillary electrophoresis-selective MS/MS of unique peptide marker ions to the identification of common pathogens in clinical diagnosis. The identified peptides that matched a protein associated with a particular pathogen were selected as marker ions to identify that bacterium in clinical specimens. Thirty-four clinical specimens, obtained from pus, wound, sputum, and urine samples, were analyzed using both biochemical and selective MS/MS methods. The bacteria in these clinical samples were cultivated directly, without prior isolation of a pure colony, before performing the selective MS/MS analyses. The match with respect to the pathogens identified was good between the biochemical and the selective MS/MS methods; the matching rate was 91%. The rate was as high as 97% when not considering two specimens where the bacteria were not grown successfully.

Electrospray-Assisted Laser Desorption Ionization Mass Spectrometry [ 下載 PDF ]

Jentaie Shiea

Electrospray-assisted laser desorption ionization (ELDI), a combination of electrospray ionization and laser desorption, is an ambient ionization source developerd in our laboratory. ELDI MS is consisted of a laser set, electrospray system, sampling platform and mass analyzer. The principle of this instrument is to laser desorb the chemicals from the surface of sold or liquid; the desorbed molecules are then post-ionized in an ESI plume to form singly or multiply charged ions; these ions are subsequently detected by the mass analyzer attached to the source. Sample pretreatment in ELDI MS analysis is minimum or unnecessary.

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Study on Silicon Wafer with Various Resistivities Utilizing THz Time-Domain Spectroscopy [ 下載 PDF ]

Shian-Wen Chang, Po-Li Chen, Chun-Jen Weng, Jr-Jung Yang, Shyh-Shii Pai

In this study we investigated terahertz (THz) transmission characteristics on Si wafer samples with various resistivities (0.008, 1, 11510 Ω·cm) using a THz time-domain spectroscopy (THz-TDS) apparatus. For this THz- TDS system, there were two testing positions for THz transmission measurements, one provided parallel THz waves for sizable samples with a diameter of about 50 mm, and the other one then focused THz radiation onto a cross-section of about 2 mm diameter where applied to a small-size material. We obtained a higher THz transmission at the focused position for THz waves than the parallel testing position which might be due to a nonuniform cross-section field distribution in the parallel THz beam. Our study of the THz-TDS on Si wafers indicated that there was of about 60% transmission for resistivity larger than 1 Ω·cm. The related analysis for the complex refractive index of Si samples in THz range will be discussed.

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HarmoniX^TM — Nanoscale Material Property Mapping [ 下載 PDF ]

Yen-Fu Chen, Cliff Tseng, J. J. Hsieh, Mark Chang

HarmoniX is one of surface material property measurement technology based upon tapping mode AFM. While scanning the surface topography, it captures elasticity and adhesion simultaneously. Comparing with other technology, HarmoniX has advantages of non-destructive, real time, high resolution and quantitative measurement. By measuring torsional multiple harmonics, the frequency-domain signals could be transformed into force curve signal, and the surface property mapping of elasticity and adhesion could be reconstructed. Special-designed probes are also used to increase the S/N ratio. Comparing with phase image, which is also based upon tapping mode AFM, HarmoniX provides quantitative result of viscoelasticity at the same resolution, and the image contrast remains the same while applying different measuring force.

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Gamut Boundary Description (GBD) of Multi-Primary Color Displays [ 下載 PDF ]

Mang Ou-Yang, Ting-Wei Huang, Yi-Ting Kuo

The display of color images needs the color reproductions of real object color. The multi-primary color displays can demonstrate easily more colors of human visual perception. However, color images transforming between different devices require an appropriate color mapping for displaying colors, and the first step of color mapping is the construction of color volume boundary of device. The paper proposes the color gamut boundary of multi-primary color devices, and the color points on the color volume boundary of multi-primary color devices can be obtained by setting appropriate digital information. The construction of color volume boundary based on these color points is quick and effective.