• Mass Spectrometry Letters
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• v.3 no.2
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• pp.29-38
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• 2012

A new approach of volatile compounds analysis is proposed using a linear ion trap Orbitrap mass spectrometer coupled with gas chromatography through an atmospheric pressure photoionization interface. In the proposed GC-HRMS/MS approach, direct chemical composition analysis is made for the precursor ions in high resolution MS spectra and the structural identifications were made through the database search of high quality MS/MS spectra. Successful analysis of a complex perfume sample was demonstrated and compared with GC-EI-Q and GC-EI-TOF. The current approach is complementary to conventional GC-EI-MS analysis and can identify low abundance co-eluting compounds. Toluene co-sprayed as a dopant through API probe significantly enhanced ionization of certain compounds and reduced oxidation during the ionization.

• Mass Spectrometry Letters
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• v.7 no.3
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• pp.69-73
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• 2016

High-resolution quadrupole-Orbitrap mass spectrometry (HRMS), with high-resolution (> 10,000 at full-width at half-maximum) and accurate mass (< 5 ppm deviation) capabilities, plays an important role in the structural elucidation of drug metabolites in the pharmaceutical industry. ML106, a derivative of imidazobenzimidazole, decreased melanin content and tyrosinase activity in a dose-dependent manner. Here, we investigated the phase 1 metabolic pathway of ML106 using HRMS in human liver microsomes (HLMs) and recombinant cDNA-expressed cytochrome P450 (CYP). After the incubation of ML106 with pooled HLMs and recombinant cDNA-expressed CYP in the presence of NADPH, five phase 1 metabolites, including three mono-hydroxylated metabolites (M1-3) and two di-hydroxylated metabolites (M4 and M5), were investigated. The metabolite structures were postulated by the elucidation of protonated mass spectra using HRMS. The CYP isoforms related to the hydroxylation of ML106 were studied after incubation with recombinant cDNA-expressed CYP. Here, we identified the phase 1 metabolic pathway of ML106 induced by CYP in HLMs.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.409-419
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• 2013

In this study, the analytical method for 27 residual pharmaceuticals in raw water was developed. Online sample preconcentration/extraction and analysis with high resolution Orbitrap mass spectrometry (LC-ESI/Orbitrap MS) were performed. The calibration curves showed good linearities (above $r^2$ = 0.998) in the range of 5 ~ 1,000 ng/L. The method detection limit and the limit of quantification were 1.1 ~ 10.0 ng/L and 3.4 ~ 31.7 ng/L, respectively. Recoveries of the target compounds were between 70.1% and 115.8% (except cefadroxil, cefradine, vancomycin, and iopromide (50.2 ~ 67.0%)). The optimized analytical method can be useful to determine the residual pharmaceuticals in raw water.

• Korean Journal of Environmental Agriculture
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• v.36 no.4
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• pp.269-278
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• 2017

BACKGROUND: The objective of this study was to evaluate screening method of residual multi pesticides in dead birds by Orbitrap high resolution mass spectrometry (HRMS) to identify the cause of death for birds. METHODS AND RESULTS: Extraction and clean-up method of residual pesticides in liver of dead birds was used QuEChERS (Quick Easy Cheap Effective Rugged and Safe) and method validations was conducted using liquid chromatography and gas chroamtography with triple-quadrupole mass spectrometer (LC/MS/MS and GC/MS/MS) Also, we were evaluated screening method for the determination of residual pesticides in liver of dead birds by LC and GC Orbitrap Mass Spectrometry. Results of method validations, Correlation coefficients of the matrix matched calibration curves were >0.978, and the method detection limits (MDLs) and limits of quantitation (LOQ) were 2.8~72.1 ng/g (18.4 ng/g on average) and 9.0~230 ng/g (58.5 ng/g on average). The accuracy ranged from 69.1%to 130% (103% on average), and the precision values were less than 14.8%(3.8%on average). The screening of residual pesticides in liver of dead birds by LC and GC Orbitrap HRMS was detected monocrotophos, carbofuran, carbosulfan, deltametrin, benfuracarb, carbofuran, phosphamidon, prochloraz in investigated samples. CONCLUSION: This results showed that accurate mass were extraction of residual pesticides in dead birds by Orbitrap HRMS. It suggested that this screening method is applicable to the residual pesticide analysis for the cause of death as a main tool.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.172-178
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• 2021

HYIpro-3-1 is an adjuvant for preventing or treating inflammatory growth diseases. In this study, we identified the metabolic pathway of HYIpro-3-1 in human liver microsomes (HLMs) by quadrupole-orbitrap high-resolution mass spectrometry (HR-MS) and characterized the major human cytochrome P450 (CYP). Ten metabolites were identified, including one O-demethylation (M1), two O-demethylation and monohydroxylation (M2 and M3), and seven monohydroxylation metabolites (M4-M10). Based on the HR-MS² spectra, the metabolites are divided into two groups of monohydroxylated metabolites according to the hydroxylation position. We verified that HYIpro-3-1 is metabolized by CYP in HLMs, CYP2B6 is mainly involved in O-demethylation, and various CYPs are involved in the monohydroxylation of HYIpro-3-1.

• Mass Spectrometry Letters
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• v.3 no.2
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• pp.50-53
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• 2012

After success of sildenafil for the treatment of erectile dysfunction, a large number of its analogues have been approved from FDA. Recently, the illegal dietary supplements which include sildenafil, vardenafil, tadalafil, or analogues of these drugs as ingredient have been widely distributed. Therefore, the determination of the residue of synthetic phosphodiesterase- 5 (PDE-5) inhibitors in dietary supplements is highly required due to indiscriminate and unintentional overdose caused nausea, chest pains, fainting and irregular heartbeat. In this paper, we report a rapid and sensitive analytical method for the simultaneous determination of nine phosphodiesterase-5 inhibitors by liquid chromatography-high resolution mass spectrometry. The present method was found to be accurate and reproducible with 40 ${\mu}g$/g of the limit of quantification for the nine PDE-5 inhibitors. The developed method can be successfully applied to the analysis of the seven illegal dietary supplements.

• Mass Spectrometry Letters
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• v.7 no.4
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• pp.111-115
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• 2016

Glycerol was identified and isolated from endogenous interferences during analysis of human urine using high-resolution mass spectrometry (HRMS) for doping control. Urinary sample preparation was simple; the samples were diluted with an organic solvent and then analyzed using a liquid chromatography-mass spectrometry ("dilute and shoot" method). Although the interfering ion peaks were observed at the similar retention time of glycerol, the inference could be identified by isolation with HRMS and further investigation. Thus, creatinine was identified as the endogenous interference for glycerol analysis and it also caused ion suppression resulting in the decrease of glycerol signal. This study reports the first identification and efficient isolation of endogenous interferences in human urine for "dilute and shoot" method. The information about ion suppression could be novel to prevent overestimation or a false result for antidoping analysis.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.843-850
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• 2012

Due to the fast response to algae bloom issue in drinking water treatment plant, very fast determination methodology for algal toxin is required. In this study, column switching technique based online preconcentration method was combined with high resolution full scan mass spectrometer to save sample preparation time and to obtain fast and accurate result. After parameter optimization of online preconcentration, 1mL filtered sample was directly injected to trap column with switching valve system. Next, target toxins are eluted by 98% acetonitrile and analysed with 150 - 1,100 amu scan range at 50,000 resolving power. Method detection limit (MDL) for microcystin-LR, the most toxic isomer, was 0.1 ng/mL and others such as microcystin-YR, microcystin-RR and nodularin were 0.08, 0.03 and 0.04 ng/mL, respectively. This is the best improved sensitivities with 1mL volume in the literature. Furthermore, due to the use of ultra pressure HPLC (UPLC), the whole method run was completed in 4 min. Real sample applications for 173 sample including 55 surface water and 118 treatment plant samples for raw and treated water could be done within 16 hours. In our calculation, this methodology is roughly 80% faster than the previous manual solid-phase extraction with LC-MS/MS method.

• Journal of the Korean Wood Science and Technology
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• v.51 no.3
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• pp.157-172
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• 2023

Azadirachta excelsa, is a plant belonging to the same genus as Indian neem (Azadirachta indica), and its use as a pesticide is reported by few studies. Despite being a different species, it is expected to have the same biopesticide potential as A. indica. Therefore, this study aims to investigate the anti-termite activity of n-hexane and methanol extracts of A. excelsa seed kernel at various concentrations against Coptotermes curvignathus. The methanol extract demonstrated greater termicidal activity than n-hexane at doses test of 2%, 4%, and 8%. It also showed 100% termite mortality on the third day of administering the 8% dose. According to the gas chromatography with mass spectrometry data, the putative main components of the n-hexane extract were hexadecanoic acid, ethyl ester (18.99%), 9,12-octadecadienoic acid (Z,Z)- (16.31%), and 9-octadecenal (16.23%). In contrast, the principal constituents of methanol extract were patchouli alcohol (28.1%), delta-guaiene (15.15%), and alpha-guaiene (11.93%). Furthermore, limonoids profiling of A. excelsa methanol extract was determined using Ultrahigh-performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry. The number of limonoids identified tentatively was fifteen, such as 6-deacetylnimbin, nimbolidin C, nimbolide, 6-acetylnimbandiol, 6-deacetyl-nimbinene, salannol, 28-deoxonimbolide, gedunin, nimbandiol, epoxyazadiradione, azadirone, 2',3'-dihydrosalannin, marrangin, nimbocinol, and azadirachtin. They were the same as those reported in the seed and leaves of A. indica, but its largest component in A. excelsa was 6-deacetylnimbin. As a result, the presence of these compounds may be responsible for the anti-termite activity of A. excelsa seed kernel extract. Additionally, column chromatography of methanol extract yielded 6-deacetylnimbin, which was found to be antifeedant and termiticide against C. curvignathus.