• Mass Spectrometry Letters
• /
• v.12 no.4
• /
• pp.159-162
• /
• 2021

The fragmentation pattern of four hindered phenol antioxidants was investigated using ammonium and lithium ions as the additives for ionization. Due to different binding geometries and interactions, they underwent different characteristic fragmentation reactions providing useful complementary information for structural analysis of hindered phenol antioxidants. Ammonium ion adducts were fragmented successively until all t-butyl groups were lost in the form of isobutylene and allowed the estimation of the number of t-butyl groups present in the molecule. Lithium ion adducts produced fragment ions from major backbone cleavage, on the other hand, which provide more crucial information for the identification of detailed backbone structure.

• Analytical Science and Technology
• /
• v.32 no.4
• /
• pp.121-130
• /
• 2019

Alumina is one of the most important ceramic materials because of its useful physical and chemical properties. Recently, high-purity alumina has been used in various industrial fields. This leads to increasing demand for reliable elemental analysis of impurities in alumina samples. However, the chemical inertness of alumina makes the sample preparation for conventional elemental analysis a tremendously difficult task. Herein, we demonstrated the feasibility of laser ablation for effective sampling of alumina powder. Laser ablation performs sampling rapidly without any chemical reagents and also allows simultaneous optical emission spectroscopy and mass spectrometry analyses. For six alumina samples including certified reference materials and commercial products, laser-induced breakdown spectroscopy (LIBS) and laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) analyses were performed simultaneously based on a common laser ablation sampling. LIBS was found to be useful to quantify alkali and alkaline earth metals with limits-of-detection (LODs) around 1 ppm. LA-ICP-MS could quantify transition metals such as Ti, Cu, Zn, and Zr with LODs in the range from a few tens to hundreds ppb.

• KSBB Journal
• /
• v.31 no.4
• /
• pp.263-269
• /
• 2016

For decades, the microorganisms in arctic soils have been newly discovered according to the climate change and global warming. In this study, the chemical structure of a lipid A molecule from Pseudomonas sp. strain PAMC 28615 which was newly discovered from arctic soils was characterized by mass spectrometric approaches such as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and MALDI multi-stage tandem mass spectrometry (MS). First, lipopolysaccharide (LPS) from Pseudomonas sp. strain PAMC 28615 was extracted and subsequently hydrolyzed to obtain the lipid A. The parent ion peak at m/z 1632 was determined by MALDI-TOF MS, which also can validate our lipid A purification method. For detailed structural determination, we performed the multiple-stage tandem mass analysis ($MS^4$) of the parent ion, and subsequently the abundant fragment ions in each MS stage are tested. The fragment ions in each MS stage were produced from the loss of phosphate groups and fatty acyl groups, which could be used to confirm the composition or the position of the lipid A components. Consequently, the mass spectrometry-based lipid A profiling method could provide the detail chemical structure of lipid A from the Pseudomonas sp. strain PAMC 28615 as an arctic bacterium from the frozen arctic soil.

• Journal of KIISE:Software and Applications
• /
• v.34 no.10
• /
• pp.889-899
• /
• 2007

In proteomics, recent advancements In mass spectrometry technology and in protein extraction and separation technology made high-throughput analysis possible. This leads to thousands to hundreds of thousands of MS/MS spectra per single LC-MS/MS experiment. Such a large amount of data creates significant computational challenges and therefore effective data analysis methods that make efficient use of computational resources and, at the same time, provide more peptide identifications are in great need. Here, SIFTER system is designed to avoid inefficient processing of shotgun proteomic data. SIFTER provides software tools that can improve throughput of mass spectrometry-based peptide identification by filtering out poor-quality tandem mass spectra and estimating a Peptide charge state prior to applying analysis algorithms. SIFTER tools characterize and assess spectral features and thus significantly reduce the computation time and false positive rates by localizing spectra that lead to wrong identification prior to full-blown analysis. SIFTER enables fast and in-depth interpretation of tandem mass spectra.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.8
• /
• pp.1235-1240
• /
• 2005

A combination of electrospray ionization and tandem mass spectrometry was used to characterize the scavenging reactions of acrylamide (AA) in the presence of glutathione (GSH) in vitro. In the presence of GSH, AA was deactivated effectively and scavenged by reactions consuming small amount of GSH. Reaction products and structural information were identified using collision-induced dissociation (CID) in an ion trap mass spectrometer. In the mixture of GSH and AA, significant increase in abundance of fragment ion peak was observed at m/z 233, which was identified as $[Cys-Glu]^+$, formed by the elimination of glycine moiety of GSH. GSH also contributes to the AA scavenging reaction by conjugating with AA through the sulfhydryl group in cysteine moiety. The probable scavenging reaction pathway of AA in the presence of GSH has been proposed based on the CID experimental data.

• Journal of Genetic Medicine
• /
• v.4 no.1
• /
• pp.53-63
• /
• 2007

Purpose : Tandem mass spectrometry (MS/MS) is effective screening test for inherited metabolic diseases. In this study, we estimate potential costs and benefits of using tandem mass spectrometry (MS/MS) to screen new borns for inherited metabolic diseases (phenylketonuria, BH4 deficiency, citrullinemia, maple syrup urine disease, propionic aciduria, isovaleric aciduria, glutaric aciduria type 1, LCHAD deficiency) in Korea. Methods : From April 2001 to March 2004, 79,179 new borns were screened for amino acid disorders, organic acid disorders, and fatty acid oxidative disorders. Twenty-eight new borns were diagnosed with one of the metabolic disorder and the collective estimated prevalence amounted to 1 in 2,800 with a sensitivity of 97.67%, a specificity of 99.28%, a recall rate of 0.05%, and a positive preditive value of 6.38%. We calculated and compared the total costs in case when neonatal screening on pheny lketonuria, BH4 deficiency, citrullinemia, maple syrup urine disease, propionic aciduria, isovaleric aciduria, glutaric aciduria type 1, LCHAD deficiency is implemented, and when not. Results : If the neonatal screening on pheny lketonuria, BH4 deficiency, citrullinemia, maple syrup urine disease, propionic aciduria, isovaleric aciduria, glutaric aciduria type 1, LCHAD deficiency is implemented, total benefits far exceed costs at a ratio of 1.40:1. Conclusion : Although, this study only concerns the monetary aspects of the neonatal screening, tandem mass spcetrometry for neonatal screening is cost-effective compared with not screening. The study appears to support the introduction of tandem mass spectrometry into a Korea neonatal screening programme for inherited metabolic diseases.

• Mass Spectrometry Letters
• /
• v.2 no.3
• /
• pp.65-68
• /
• 2011

The effects of column length and particle size on the efficiency of separation and characterization of phospholipids (PLs) are investigated using nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS). Since PLs are associated with cell proliferation, apoptosis, and signal transduction, it is of increasing interests in lipidomics to establish reliable analytical methods for the qualitative and quantitative profiling of PLs related to biomarker development in adult diseases. Due to the complexity of PLs, the preliminary separation of PLs is necessary prior to MS analysis. In this study, length of capillary column and the particle size of reversed phase ($C_{18}$) packing materials are varied to find a reliable condition for the high speed and high resolution separation using 8 PL standard mixtures. From experiments, it was found that a capillary column of nLC-ESI-MS-MS analysis for PL mixtures can be minimized to a 5 cm long pulled tip column packed with 3 ${\mu}m$ $C_{18}$ particles without losing resolution.

• Mass Spectrometry Letters
• /
• v.8 no.3
• /
• pp.53-58
• /
• 2017

Glycated hemoglobin ($HbA_{1c}$) has been commonly used to screen and diagnose for patients with diabetes mellitus. Here the accelerated procedure of microwave-assisted sample treatment from acid hydrolysis to enzyme digestion followed by isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) was optimized and applied to measure $HbA_{1c}$ in an effort to speed up analysis time. First, two signature peptides of $HbA_{1c}$ and hemoglobin $A_0$ were certified with amino acid analysis by setting optimized acid hydrolysis conditions to $150^{\circ}C$, 1.5 h and $10{\mu}M$ sample concentration in 8 M hydrochloric acid. Consequently, the accurate certified peptides above were used as calibration standards to implement the proteolytic procedure with endoproteinase Glu-C at $37^{\circ}C$, 700 W for 6 h. Compared to the traditional method, the microwave heating not only shortened dramatically sample preparation time, but also afforded comparable recovery yields. The optimized protocol and analytical conditions in this study are suitable for a primary reference method of $HbA_{1c}$ quantification with full SI-traceability and other similar proteins in complex biological samples.

• Mass Spectrometry Letters
• /
• v.12 no.2
• /
• pp.31-40
• /
• 2021

Probable human carcinogenic compounds nitrosamines, have been detected as by-product impurities in sartan pharmaceuticals in recent years which has drawn worries for medication safety. To provide a sensitive and effective method for the quality control of sartan pharmaceuticals, this study established a feasible gas chromatography-tandem mass spectrometry (GC-MS/MS) method for simultaneous determination of 13 nitrosamines. The target analytes were separated on a DB-WAX Ultra Inert column (30 m × 0.25 mm; i.d., 0.25 ㎛) and were then subjected to electron impact ionization in multiple reaction monitoring mode. The established method was validated and further employed to analyze authentic samples. Limits of detection (LODs) and limits of quantification (LOQs) of the 13 nitrosamines were 15-250 ng/g and 50-250 ng/g, respectively, which also exhibited intra-day and inter-day accuracies of 91.4-104.8%, thereby satisfying validation criteria. Five nitrosamines, viz., N-nitrosodiethylamine, N-nitrosodimethylamine, N-nitrosodiphenylamine, N-nitrosomorpholine, and N-nitrosopiperidine were detected at concentrations above their LODs in 68 positive samples out of 594 authentic samples from seven sartans.

• Mass Spectrometry Letters
• /
• v.14 no.4
• /
• pp.153-159
• /
• 2023

The copper ion, Cu(II), binding sites for amyloid fragment Aβ1-16 (=Aβ16 ) were investigated to explain the biological activity difference in the Aβ16 aggregation process. The [M+Cu+(z-2)H]^z+ (z = 2, 3 and 4, M = Aβ16 monomer) and [D+Cu+(z-2)H]^z+ (z = 3 and 5, D = Aβ16 dimer) structures were investigated using electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Fragment ions of the [M+Cu+(z-2)H]^z+ and [D+Cu+(z-2)H]^z+ complexes were observed using collision-induced dissociation MS/MS. Three different fragmentation patterns (fragment "a", "b", and "y" ion series) were observed in the MS/MS spectrum of the (Aβ16 monomer or dimer-Cu) complex, with the "b" and "y" ion series regularly observed. The "a" ion series was not observed in the MS/MS spectrum of the [M+Cu+2H]⁴⁺ complex. In the non-covalent bond dissociation process, the [D+Cu+3H]⁵⁺ complex separated into three components ([M+Cu+H]³⁺, M³⁺, and M²⁺), and the [M+Cu]²⁺ subunit was not observed. The {M + fragment ion of [M+Cu+H]³⁺} fragmentation pattern was observed during the covalent bond dissociation of the [D+Cu +3H]⁵⁺ complex. The {M + [M+Cu+H]³⁺} complex geometry was assumed to be stable in the [D+Cu+3H]⁵⁺ complex. The {M + fragment ion of [M+Cu]²⁺} fragmentation pattern was also observed in the MS/MS spectrum of the [D+Cu+H]³⁺ complex. The {M + [y₉+Cu]¹⁺} fragment ion was the characteristic fragment ion. The [D+Cu+H]³⁺ and [D+Cu+3H]⁵⁺ complexes were likely to form a monomer-monomer-Cu (M-M-Cu) structure instead of a monomer-Cu-monomer (M-Cu-M) structure.