• Mass Spectrometry Letters
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• v.10 no.4
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• pp.108-111
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• 2019

The hydrolysis of penicillin G, carbenicillin and ampicillin in pure water at room temperature was studied by high pressure liquid chromatography electrospray ionization mass spectrometry. Hydrolysis of ampicillin did not occur under these conditions; however, penicillin G and carbenicillin were completely hydrolyzed after seven days. A short interpretation of this difference is proposed. The mass spectrometric behaviour, namely ESI response and fragmentation pathway, of hydrolyzed penicillin G and hydrolyzed carbenicillin have been also discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.384.1-384.1
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• 2016

We reported that amorphous silicon (a-Si) thin film provide sample plate exhibiting a multimodality to measure biomolecules by secondary ion mass spectrometry (SIMS) and laser desorption/ionization mass spectrometry (LDI-MS). Kim et al.1 reported that a-Si thin film were suitable to detect small molecules such as drugs and peptides by SIMS and LDI-MS. Recently, bacterial identification has been required in many fields such as food analysis, veterinary science, ecology, agriculture, and so on.2 Mass spectrometry is emerging for identifying and profiling microbiology samples from its advantageous characters of label-free and shot-time analysis. Five species of bacteria - S. aureus, G. glutamicum, B. kurstaki, B. sphaericus, and B. licheniformis - were sampled for MS analysis without lipid extraction in sample preparation steps. The samples were loaded onto the a-Si thin film with a thickness of 100 nm which did not only considered laser-beam penetration but also surface homogeneity. Mass spectra were recorded in both positive and negative ionization modes for more analytical information. High reproducibility and sensitivity of mass spectra were demonstrated in a mass range up to mass-to-charge ratio(m/z) 1200 by applying the a-Si thin film in mentioned above MS. Principle component analysis (PCA) - a popular statistical analysis widely used in data processing was employed to differentiate between five bacterial species. The PCA results verified that each bacterial species were readily distinguished and differentiated effectively from our MS approach. It shows a new opportunity to rapid bacterial profiling and identification in clinical microbiology. More details will be discussed in the presentation.

• Mass Spectrometry Letters
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• v.3 no.4
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• pp.108-111
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• 2012

An experimental study on the nascent product of the OH heterogeneous reaction with NaCl was performed under dry and wet conditions using a bead-filled flow tube system coupled to a high-pressure chemical ionization mass spectrometer. The ozone concentration in the flow tube for the atomic hydrogen removal was varied in order to control the conversion reaction of molecular chlorine into HCl for the identification of the nascent product. The mass spectrometric observation was that the $O_3$ introduction reduced the concentration HCl, while it increased the concentration of $Cl_2$ and ClO. Based on the experimental results, we suggest that the nascent product of the titled reaction is gaseous $Cl_2$, which is followed by fast conversion into HCl in presence of H. No significant difference in the concentration profile between under dry and wet (RH = 2%) conditions was observed.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.480-507
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• 2003

A rapid and efficient method for analyzing the nonionic surfactants and silicone polymers, which control the shape and characteristics of cosmetic products and give influence on product quality, has been developed using Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI- TOF IMS). The MALDI-TOF/MS could easily and effectively determine the molecular weight distribution and monomer units of nonionic surfactants. As a result, creating a library of mass spectrum data of surfactants used in cosmetic products using MALDI-TOF/MS and analyzing surfactants extracted from the products may become a useful method for detailed structural characterization of the surfactants. Furthermore, the MALDI-TOF/MS analysis was effective in obtaining the spectrum of silicone polymers from which the molecular weight distribution could be determined. The repetition units and structural data could also be obtained through molecular mass peaks. Additionally, the monomer ratio and terminal groups as properties of silicone copolymers could be determined

• Mass Spectrometry Letters
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• v.14 no.4
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• pp.121-140
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• 2023

It is becoming more and more clear that each cell, even those of the same type, has a unique identity. This sophistication and the diversity of cell types in tissue are what are pushing the necessity for spatially distributed omics at the single-cell (SC) level. Single-cell chemical assessment, which also provides considerable insight into biological, clinical, pharmacodynamic, pathological, and toxicity studies, is crucial to the investigation of cellular omics (genomics, metabolomics, etc.). Mass spectrometry (MS) as a tool to image and profile single cells and subcellular organelles facilitates novel technical expertise for biochemical and biomedical research, such as assessing the intracellular distribution of drugs and the biochemical diversity of cellular populations. It has been illustrated that ambient mass spectrometry (AMS) is a valuable tool for the rapid, straightforward, and simple analysis of cellular and sub-cellular constituents and metabolites in their native state. This short review examines the advances in ambient mass spectrometry (AMS) and ambient mass spectrometry imaging (AMSI) on single-cell analysis that have been authored in recent years. The discussion also touches on typical single-cell AMS assessments and implementations.

• Mass Spectrometry Letters
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• v.10 no.1
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• pp.11-17
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• 2019

Drosophila melanogaster (fruits fly) is a representative model system widely used in biological studies because its brain function and basic cellular processes are similar to human beings. The whole head of the fly is often used to obtain the key function in brain-related diseases like degenerative brain diseases; however the biomolecular distribution of the head may be slightly different from that of a brain. Herein, lipid profiles of the head and dissected brain samples of Drosophila were studied using electrospray ionization-mass spectrometry (ESI-MS). According to the sample types, the detection of phospholipid ions was suppressed by triacylglycerol (TAG), or the specific phospholipid signals that are absent in the mass spectrum were measured. The lipid distribution was found to be different in the wild-type and the microRNA-14 deficiency model ($miR-14{\Delta}^1$) with abnormal lipid metabolism. A few phospholipids were also profiled by comparison of the head and the brain in two fly model systems. The mass spectra showed that the phospholipid distributions in the $miR-14{\Delta}^1$ model and the wild-type were different, and principal component analysis revealed a correlation between some phospholipids (phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS)) in $miR-14{\Delta}^1$. The overall results suggested that brain-related lipids should be profiled using fly samples after dissection for more accurate analysis.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.947-950
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• 2006

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1590-1594
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• 2002

Liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) has been used for the determination of sulfonamides in meat. Five typical sulfonamides were selected as target compounds, and beef meat was selected as a matrix sample. As internal standards, sulfapyridine and isotope labeled sulfamethazine (${13}^C_6$-SMZ) were used. Compared to the results of recent reports, our result have shown improved precision to a RSD of 1.8% for the determination of sulfamethazine spiked with 75 ng/g level in meat.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.878-880
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• 2004

Revered-phase LC-electrospray ionization mass spectrometry was used to selectively determine enalapril from plasma with minimal sample preparation. Detection limit of the method was 1 ng/mL. Precision (within day and between days) and accuracy of the method at various concentrations were acceptable. The analytical technique was used for pharmacokinetic studies after administration of enalapril to human test subjects.

• Mass Spectrometry Letters
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• v.2 no.3
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• pp.69-72
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• 2011

Defective synthesis of the steroid hormones by the adrenal cortex has profound effects on human development and homeostasis. Due to the time-consuming chromatography procedure combined with mass spectrometry, the matrix-assisted laser desorption ionization method coupled to the linear ion-trap tandem mass spectrometry (MALDI-LTQ-MS/MS) was developed for quantitative analysis of 10 adrenal steroids in human serum. Although MALDI-MS can be introduced for its applicability as a high-throughput screening method, it has a limitation on reproducibility within and between samples, which renders poor reproducibility for quantification. For quantitative MALDI-MS/MS analysis, the stable-isotope labeled internal standards were used and the conditions of crystallization were tested. The precision and accuracy were 3.1~35.5% and 83.8~138.5%, respectively, when a mixture of 10 mg/mL ${\alpha}$-cyano-4-hydroxycinnamic acid in 0.2% TFA of 70% acetonitrile was used as the MALDI matrix. The limit of quantification ranged from 5 to 340 ng/mL, and the linearity as a correlation coefficient was higher than 0.988 for all analytes in the calibration range. Clinical applications include quantitative analyses of patients with congenital adrenal hyperplasia. The devised MALDI-MS/MS technique could be successfully applied to diagnosis of clinical samples.