Optimized Automatic Noise Level Calculations for Broadband FT-ICR Mass Spectra of Petroleum Give More Reliable and Faster Peak Picking Results

Hur, Manhoi,Oh, Han-Bin,Kim, Sung-Hwan Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

A new algorithm for determining noise level is proposed for more reliability in interpreting spectral data for complex Fourier transform ion cyclotron resonance (FTICR) mass spectra of petroleum. In the new algorithm, a moving window with a fixed number of data points was adopted, instead of a fixed m/z width. In the analysis of petroleum, it was found that a moving window of 50,000 or more data points was optimal. This optimized automated peak picking performed well even with frequency-dependant noise in the mass spectrum. Additionally, this fast, automated peak picking algorithm was suitable for the analysis of a large set of samples.

Optimized Automatic Noise Level Calculations for Broadband FT-ICR Mass Spectra of Petroleum Give More Reliable and Faster Peak Picking Results

Manhoi Hur,오한빈,김성환 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11

A new algorithm for determining noise level is proposed for more reliability in interpreting spectral data for complex Fourier transform ion cyclotron resonance (FTICR) mass spectra of petroleum. In the new algorithm, a moving window with a fixed number of data points was adopted, instead of a fixed m/z width. In the analysis of petroleum, it was found that a moving window of 50,000 or more data points was optimal. This optimized automated peak picking performed well even with frequency-dependant noise in the mass spectrum. Additionally, this fast, automated peak picking algorithm was suitable for the analysis of a large set of samples.

Identification and biosynthesis of acylphloroglucinols in <i>Hypericum gentianoides</i>

Crispin, Matthew C.,Hur, Manhoi,Park, Taeseong,Kim, Young Hwan,Wurtele, Eve Syrkin Blackwell Publishing Ltd 2013 Physiologia Plantarum Vol.148 No.3

<P>Species of the genus <I>Hypericum</I> contain a rich array of unusual polyketides, however, only a small proportion of the over 450 <I>Hypericum</I> species, other than the popular medicinal supplement St. John's Wort (<I>Hypericum perforatum</I>), have even been chemically characterized. <I>Hypericum gentianoides</I>, a small annual used medicinally by Cherokee Americans, contains bioactive acylphloroglucinols. Here, we identify acylphloroglucinol constituents of <I>H. gentianoides</I> and determine a potential pathway to their synthesis. Liquid chromatography/electrospray ionization‐mass spectrometry (LC/ESI‐MS) and HPLC‐UV indicate that the level of accumulation and profile of acylphloroglucinols in <I>H. gentianoides</I> vary little seasonally when grown in a greenhouse, but do vary with development and are highly dependent on the accession, highlighting the importance of the selection of plant material for study. We identify the chemical structures of the nine prevalent polyketides, based on LC/ESI‐MS and hybrid quadrupole orthogonal time‐of‐flight (Q‐TOF) mass spectrometry; these metabolites include one monomeric phlorisobutyrophenone (PIB) derivative and eight dimeric acylphloroglucinols. Q‐TOF spectrometry was used to identify eight additional PIB derivatives that were not detected by LC/ESI‐MS. These data lead us to propose that diacylphloroglucinols are synthesized via modification of PIB to yield diverse phloroglucinol and filicinic acids moieties, followed by dimerization of a phloroglucinol and a filicinic acid monomer to yield the observed complement of diacylphloroglucinols. The metabolomics data from <I>H. gentianoides</I> are accessible in plant metabolomics resource (PMR) (<url href='http://www.metnetdb.org/pmr'>http://www.metnetdb.org/pmr), a public metabolomics database with analysis software for plants and microbial organisms.</P>

Speed Improvement of an FTICR Mass Spectra Analysis Program by Simple Modifications

Sang Hyun Jeon,장형수,Manhoi Hur,Kyung-Hoon Kwon,김현식,Jong Shin Yoo,김성환,박수진,오한빈 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.9

Two simple algorithm modifications are made to the THRASH data retrieval program with the aim of improving analysis speed for complex Fourier transform ion cyclotron resonance (FTICR) mass spectra. Instead of calculating the least-squares fit for every charge state in the backup charge state determination algorithm, only some charge states are pre-selected based on the plausibility values obtained from the FT/Patterson analysis. Second, a modification is made to skip figure-of-merit (FOM) calculations in the central m/z region between two neighboring peaks in isotopic cluster distributions, in which signal intensities are negligible. These combined modifications result in a significant improvement in the analysis speed, which reduces analysis time as much as 50% for ubiquitin (8.6 kDa, 76 amino acids) FTICR MS and MS/MS spectra at the reliability (RL) value = 0.90 and five pre-selected charge states with minimal decreases in data analysis quality (Table 3).

Application of FT-ICR MS Equipped with Quadrupole Detection for Analysis of Crude Oil

Cho, Eunji,Witt, Matthias,Hur, Manhoi,Jung, Maeng-Joon,Kim, Sunghwan American Chemical Society 2017 ANALYTICAL CHEMISTRY - Vol.89 No.22

<P>Resolving power is a critical factor determining the quality of ultrahigh-resolving power mass spectra of crude oil. In this study, 7T Fourier-transform ion cyclotron mass spectrometry (FT-ICR MS), equipped with quadrupole detection, was applied and evaluated for crude oil analysis for the first time. Four spectra were obtained from two oil samples using two ionization methods. Resolving power of 1500000 was observed at <I>m</I>/<I>z</I> 400 with 4 s transient signal. Comparison with literature reports revealed that the achieved resolving power was comparable with or superior to those obtained from instruments using higher magnetic fields but without quadrupole detection. A total of 6000–10000 peaks with an S/N ratio of 3 or higher were observed from the obtained spectra and over 97% of the peaks could be assigned to appropriate chemical formulas with an error within 1 ppm. Double bond equivalents vs carbon number plots generated from the obtained data agreed well with those previously reported without quadrupole detection. Mass accuracy values of the assigned elemental formulas were examined and the average root-mean-square error was calculated to be only 160 ppb. Low unassignment rate of the observed peaks and strong agreement with previously reported results suggests that unwanted harmonics of reduced frequency are not significant for the data obtained with quadrupole detection. Overall, the data presented in this study show that FT-ICR MS equipped with quadrupole detection can be a powerful tool to examine complex mixtures like crude oil. To the best of our knowledge, this is the first paper reporting application of FT-ICR MS equipped with quadrupole detection for the oil analysis.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2017/ancham.2017.89.issue-22/acs.analchem.7b02644/production/images/medium/ac-2017-02644t_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ac7b02644'>ACS Electronic Supporting Info</A></P>

Extension of the Analytical Window for Characterizing Aromatic Compounds in Oils Using a Comprehensive Suite of High-Resolution Mass Spectrometry Techniques and Double Bond Equivalence versus Carbon Number Plot

Cho, Yunju,Birdwell, Justin E.,Hur, Manhoi,Lee, Joonhee,Kim, Byungjoo,Kim, Sunghwan ACS AMERICAN CHEMICAL SOCIETY 2017 ENERGY AND FUELS Vol.31 No.8

<P>In this study, comprehensive two-dimensional (2D) gas chromatography-mass spectrometry (GC-MS), atmospheric pressure photoionization (APPI) quadrupole-Orbitrap mass spectrometry (MS), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were used to study the aromatic fractions of crude oil and oil shale pyrolysates (shale oils). The collected data were compared and combined in the double bond equivalence (DBE) versus carbon number plot to obtain a more complete understanding of the composition of the oil fractions. The numbers of peaks observed by each technique followed the order 2D GC-MS < Orbitrap MS < FT-ICR MS. The class distributions observed by Orbitrap MS and FT-ICR MS were similar to each other but different from that observed by 2D GC-MS. The DBE and carbon number distributions of the 2D GC-MS and Orbitrap MS data were similar for crude oil aromatics. The FT-ICR MS plots of DBE and carbon number showed an extended range of higher values relative to the other methods. For the aromatic fraction of an oil shale pyrolysate generated by the Fischer assay, only a few nitrogen-containing compounds were observed by 2D GC-MS but a large number of these compounds were detected by Orbitrap MS' and FT-ICR MS. This comparison clearly shows that the data obtained from these three techniques can be combined to more completely characterize oil composition. The data obtained by Orbitrap MS and FT-ICR MS agreed well with one another, and the combined DBE versus carbon number plot provided more complete coverage of compounds present in the fractions. In addition, the chemical structure information provided by 2D GC MS could be matched with the chemical formulas in the DBE versus carbon number plots, providing information not available in ultrahigh-resolution MS results. It was therefore concluded that the combination of 2D GC-MS, Orbitrap MS, and FT-ICR MS in the DBE versus carbon number space facilitates structural assignment of heavy oil components.</P>

The ‘hybrid cell’: a new compensated infinity cell for larger radius ion excitation in Fourier transform ion cyclotron resonance mass spectrometry

Kim, Sunghwan,Choi, Myoung Choul,Hur, Manhoi,Kim, Hyun Sik,Yoo, Jong Shin,Hendrickson, Christopher L.,Marshall, Alan G. John Wiley Sons, Ltd. 2008 Rapid communications in mass spectrometry Vol.22 No.9

<P>A new ‘hybrid’ ion cyclotron resonance (ICR) trap is proposed and analyzed by computer simulations. The trap is basically a hybrid of a segmented end cap (Infinity) and capacitively coupled cylindrical cell, with additional electrodes placed at the center of each end cap. The new trap produces an on-axis electric field z-profile similar to that of the Infinity cell or capacitively coupled open cylindrical cell during ion excitation. Simion simulations demonstrate that, during detection, appropriate changes of the potentials applied to the two new sets of electrodes produce a radial electric field z-profile that more closely approaches that for an ideal axial three-dimensional quadrupolar potential at high post-excitation ICR orbital radius, for improved signal-to-noise ratio and resolving power, and minimal m/z-discrimination. Copyright © 2008 John Wiley & Sons, Ltd.</P>