• Bulletin of the Korean Chemical Society
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• v.21 no.5
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• pp.471-476
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• 2000

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface (LC/APCI/MS) is evaluated for the simultaneous determination of carbamate pesticides and organophosphorus pesticides in a single chromatographic analysis. APCI mass spectra of those compounds were obtrained to study their ionization characteristics. APCI provided abundant ions such as protonated molecules and characteristic fragment ions for carbamate pesticides and organophosphorus pesticides. To evaluate the feasibility of the LC/APCI/MS for a routine quantitative analysis, the linearity and repeatability of LC/APCI/MS were examined by measuring standard solution mixtures of five carbamate pesticides and four organophosphorus pesticides over the range of 1 to 100 ㎍/mL. Teh peak areas in chromatograms of characteristic ions for those compounds showed less than 3% of variation from run to run. The standard calibration curves for the nine pesticides show good linearity in the concentration range. The detection limits of the LC/APCI/MS system for those compounds range from 0.006 to 0.2 ng.

• Analytical Science and Technology
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• v.16 no.2
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• pp.125-133
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• 2003

In order to determine the contents of trans-resveratrol in red wine, which was mainly consumed in Korea, both LC/MS-ESI and LC/MS-APCI methods were used after solid-phase (Sep-Pak $C_{18}$-cartridges) extraction. The contents of trans-resveratrol obtained by LC/MS-ESI were detected in the range of $0.06-4.31{\mu}g/mL$. The recoveries were ranged from 88.4 to 97.9%. The values of relative standard deviation were ranged from 0.6 to 4.6% and the detection limit was $0.001{\mu}g/mL$. The contents of trans-resveratrol obtained by LC/MS-APCI were detected in the range of $0.09-4.02{\mu}g/mL$ and the detection limit was $0.005{\mu}g/mL$.

• Bulletin of the Korean Chemical Society
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• v.29 no.9
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• pp.1847-1849
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• 2008

• Analytical Science and Technology
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• v.30 no.2
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• pp.102-111
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• 2017

Here we reported a methodology for identification of triacylglycerols (TAGs) and diacylglycerols (DAGs) in coix seed by preparative thin layer chromatography (prep-TLC) and non-aqueous reversed-phase liquid chromatography (NARP LC)-atmospheric pressure chemical ionization (APCI) tandem mass spectrometry (MS/MS). Lipid components were extracted from coix seed by reflux extraction using n-hexane for 3 hr. TAGs and DAGs in coix seed extract were effectively purified and isolated from matrix interferences by prep-TLC and then analyzed by LC-APCI-MS and MS/MS for identification. TAGs were effectively identified taking into consideration of their LC retention behavior, APCI-MS spectra patterns, and MS/MS spectra of $[DAG]^+$ ions. In MS/MS spectra of TAGs, diacylglycerol-like fragment $[DAG]^+$ ions were useful to identify TAGs with isobaric fragment ions. Based on an established method, 27 TAGs and 8 DAGs were identified in coix seed extract. Among them, 15 TAGs and 8 DAGs were for the first time observed in coix seed. Interestingly, some of TAGs isolated by prep-TLC were partly converted into DAGs through probably photolysis process during storing in room temperature. Thus, degradation phenomenon of TAGs should be considered in the quality evaluation and nutritional property of coix seed. LC-APCI-MS/MS combined with prep-TLC will be practical method for precise TAG and DAG analysis of other herbal plants.

• 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.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.280.2-280.2
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• 2003

The applicability of liquid chromatography-atmospheric-pressure chemical-ionization mass spectrometry (LC-APCI-MS) for the determination of 13C-urea in 13C-urea/PEG capsules has been studied. It is essential to assess the stability of a newly developed low-dose (38 mg) 13C-urea/PEG capsule. which will be used for 13C-urea breath test (13C-UBT) to detect Helicobacter pylori infection. (omitted)

• Analytical Science and Technology
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• v.16 no.6
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• pp.488-498
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• 2003

By LC/MS/MS, the analytical method of sildenafil and its analogues (homosildenafil, vardenafil and tadalafil) used as used medical treatment of impotence was established. electrosprary ionization (ESI) and atmospheric pressure chemical ionization (APCI) as a ionization method were applied. Several parameter were varied and the sensitivity and reproducibility were compared. In LC/ESI-MS method, capillary voltage, cone voltage, extractor, entrance and RF lens to create appropriate productr ions for multiple reaction monitoring (MRM) were variable parameter, but the formation of the other product ions except the precursor ion could not detect. And the value of entrance, collision energy, exit, corona voltage, cone voltage, extractor, RF lens, cone gas, and desolvation gas in APCI mode were varied, only the creation pattern of fragment ions by the change of RF lens value were detected, and the limit of detection was decreased due to the increase of S/N. Ten millimole ammonium formate (pH 4.8):acetonitrile=70:30 by isocratic elution in HPLC system was shown the maximum sensitivity in MS, the detection limit of sildenafil, homosildenafil, vardenafil and tadalafil obtained by ESI-MRM were 0.10, 0.025, 0.025, and $0.25{\mu}g/mL$ at S/N>5, respectively.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1333-1341
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• 2009

Haematococcus pluvial is, a green alga, accumulates astaxanthin (3,3'-dihydroxy-$\beta$,$\beta$'-carotene-4,4'-dione) upto 2-3% on a dry weight basis. In the present study, identification of carotenoids from Haematococcus cyst cell extract by HPLC and LC-MS (APCI) and their antioxidant properties were evaluated in in vitro model systems. The extract exhibited 89% and 78% antioxidant activities in the $\beta$-carotene linoleate model and the hydroxyl radical scavenging model, at 9 ppm of total carotenoid, respectively. The extract also showed 80%, 85%, and 79% antioxidant activities against lipid peroxidation in the kidney, brain, and liver of rats. Low-density lipoprotein oxidation induced by $Cu^{2+}$ ions was also protected (45%, 64%, and 75%) by the extract in a dose-dependent manner with different carotenoid levels. Thiobarbituric acid reactive substances concentration in the blood, liver, and kidney of rats were also significantly (p<0.005) decreased in H. pluvialis-treated rats. The potent antioxidant activity is attributable to various carotenoids present in the extract.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1489-1496
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• 2009

This study was done for the determination and excretion profile of adrenosterone and its metabolites in human urine using both liquid chromatography with atmospheric pressure chemical ionization mass spectrometry and gas chromatography with mass spectrometry. Adrenosterone and its two metabolites were detected in human urine after administration a healthy volunteer with 75 mg of adrenosterone. We found that adrenosterone-M1 ($C_{19}H_{26}O_3$) was a reduction and adrenosterone-M2 ($C_{19}H_{26}O_4$) was a hydroxylation at C-ring, which did not know the exact position of the C-ring. The adrenosterone parent was detected by GC/TOF-MS, but not detected by LC/APCI/MS because of low intensity. Adrenosterone and its two metabolites were excreted as their glucuronided fractions. The recovery of this method ranged from 100.7 to 118.4% and the reproducibility and accuracy test were 85.5 to 112.0% and 1.1 to 8.4%, respectively. The excretion studies showed that adrenosterone and its metabolites were detectable in human urine during a 48 h period after oral administration, with maximum level of excretion at 4.1 h. The glucuro-/sulfaconjugated ratio of adrenosterone, M1 and M2 was 0.73 ${\pm}$ 0.03, 0.96 ${\pm}$ 0.06 and 0.89 ${\pm}$ 0.03 (n = 6), respectively. The amounts of adrenosterone excreted in urine were 14.75 ng for 48 h. Also, the maximum level of androsterone and 11$\beta$-hydroxy androsterone, which were endogenous steroids, were reached 4.1 h after the oral administration of adrenosterone.

• Journal of the Korean Chemical Society
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• v.61 no.2
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• pp.51-56
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• 2017

N-nitrosamines are the nitroso compounds which are produced by nitrosation reactions of the secondary amine and nitrite under acidic conditions. Approximately 300 species of N-nitrosamine have been tested for carcinogenicity in laboratory experiments, with 90% of them demonstrated carcinogenic effects different animal species, including higher primates. In 1978, IARC classified NDMA and NDEA as Group 2A, and NDPA, NDBA, NPIP, NPYR and NMOR as Group 2B. In this study, we established pretreatment and analytical method for N-nitrosamines (NDMA, NDEA, NMEA, NDPA, NDBA, NPIP, NPYR and NMOR) in human urine for biological monitoring of N-nitrosamines. The analytes were extracted using solid phase extraction (SPE), then quantitative analysis was performed by LC-(APCI)-MS/MS. The accuracies of the established method were between 85.8~108.7% and precisions were lower than 20%. The limit of detection (LOD) were between 0.0002 (NDBA) and 0.0793 (NDMA) ng/ml. The linearity obtained was satisfying for the 8 N-nitrosamines, with a coefficient of determination ($r^2$) higher than 0.999. The mean concentrations of N-nitrosamines in the urine were 2.645 mg/g creatinine for NDMA, 0.067 mg/g creatinine for NDEA, 0.009 mg/g creatinine for NMEA, 0.011 mg/g creatinine for NDBA, 0.271 mg/g creatinine for NPIP and 0.413 mg/g creatinine for NPYR. NDPA and NMOR were not detected. It can be used as a instrumental methodology for evaluation and risk assessment of human exposure to N-nitrosamines for the further research.