• Analytical Science and Technology
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• v.10 no.1
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• pp.9-17
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• 1997

Nitrophenols are a group of important priority pollutants classified by the US Environmental Protection Agency. Reverse-phase liquid chromatographic method combined with mass spectromethy employing atmospheric pressure chemical ionization(APCI) interface is utilized to determine a mixture of nitrophenols in water matrix without any pretreatment. The sensitivity and selectivity for the identification of different kind of nitrophenols is enhanced by the use of selected ion monitoring and cone voltage fragmentation. The fragmentation patterns of nitrophenols are compared with those obtained from the collision induced dissociation(CID) MS/MS technique.

• Journal of Pharmaceutical Investigation
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• v.33 no.3
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• pp.195-199
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• 2003

The objective of this study is to investigate the pharamacokinetic parameters of decursinol following oral administration in Sprague-Dawley rats. The plasma concentration of decursinol was determined by LC/MS with APCI positive mode. The m/z value of decursinol was observed at 247. Following oral administration of decursinol extract, the apparent clearance was $5.3{\pm}2.7\;ml/hr/rat$, the absorption half life was $2.5{\pm}0.41\;hr$, the elimination half life was $3.05{\pm}1.57\;hr$, and the apparent volume of distribution was $21{\pm}12\;ml/rat$. The LC/MS method was successfully applied to the pharmacokinetic study of decursinol.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1170-1178
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• 2011

In the present study, the approach of high accuracy mass measurements for phospholipid identifications was evaluated using a 7 T ESI-FTMS/linear ion trap MS/MS. Experiments were carried out for porcine brain, bovine liver, and soybean total lipid extracts in both positive and negative ion modes. In total, 59, 55, and 18 phospholipid species were characterized in the positive ion mode for porcine brain, bovine liver, and soybean lipid extracts, respectively. Assigned lipid classes were PC, PE, PEt, PS, and SM. In the negative ion mode, PG, PS, PA, PE, and PI classes were observed. In the negative ion mode, for porcine brain, bovine liver, and soybean lipid extracts, 28, 34, and 29 species were characterized, respectively. Comparison of our results with those obtained by other groups using derivatization-LC-APCI MS and nano-RP-LC-MS/MS showed that our approach can characterize PC species as effectively as those methods could. In conclusion, we demonstrated that high accuracy mass measurements of total lipid extracts using a high resolution FTMS, particularly, 7T FTMS, plus ion-trap MS/MS are very useful in profiling lipid compositions in biological samples.

• Analytical Science and Technology
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• v.36 no.6
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• pp.281-290
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• 2023

Zidovudine is an antiretroviral agent prescribed for the prevention and treatment of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). It is typically recommended to be used in combination with other antiretroviral drugs. Zidovudine has the potential to generate N-nitrosodimethylamine (NDMA) in the presence of dimethylamine and nitrite salt under acidic reaction conditions during the drug manufacturing process. NDMA is a potent human carcinogen that may be detected in drug substances or drug products. An analytical method was developed to determine NDMA in pharmaceuticals including zidovudine using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The analysis involved reversed-phase chromatography on a Kinetex F5 column with a mobile phase comprising water-acetonitrile mixtures. The detection of positively charged ions was conducted using atmospheric pressure chemical ionization (APCI). The calibration curve demonstrated excellent linearity (r = 0.9997) across the range of 1-50 ng/mL with a highly sensitive limit of detection (LOD) at 0.3 ng/mL. The developed method underwent thorough validation for specificity, linearity, accuracy, precision, robustness, and system suitability. This sensitive and specific analytical method was applied for detecting NDMA in zidovudine drug substance and its formulation currently available in the market, indicating its suitability for drug quality management purposes.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.285-294
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• 2011

Glucosinolate (GSL) contents were investigated (i) at 1~7 days after sowing (DAS) in seed sprouts and (ii) at 3-7 weeks after sowing for the time-course. Moreover, (iii) They were compared with five different cultivars of rocket salad (Eruca sativa). Seventeen GSLs were separated by HPLC analysis, and 10 GSLs among them were identified as glucoraphanin, sinigrin, glucoalyssin, diglucothiobeinin, glucobrassicanapin, glucoerucin, glucobrassicin, dimeric, 4-mercaptobutyl GSL, 4-methoxy glucobrassicin, gluconasturttin by using LC-APCI-MS analysis, but 7 compounds were not identified. (i) The total GSL content in seed sprouts initially increased up to 3 DAS and then decreased according to their seedling growth. In particular, glucoraphanin known as a strong anti-cancer reagent was found the highest level (5.05 ${\mu}mol/g$ dry wt.) at 3 DAS. The most abundant GSL was glucoerucin ranged from 26.0~49.6 ${\mu}mol/g$ dry wt. (ii) In the time-course, the total GSL contents increased dramatically from 3-week (5.91 ${\mu}mol/g$ dry wt.) to 7-week after sowing (32.2 ${\mu}mol/g$ dry wt.). The major GSLs were glucoraphanin, glucoerucin and 4-methoxy glucobrassicin. (iii) By comparing GSL contents with five different cultivars, the total GSL contents increased from 4-week to 6-week after sowing, regardless of cultivar. In 4-week-old, the order with the total GSL content was "Rucola" > "Rocket Herbs" ${\geqq}$ "Odyssey" > "Takii" > "Herb", but in 6-week-old it is changed as "Takii" > "Herb" > "Odyssey" > "Rucola" > "Rocket Herbs" even there was almost no significantly difference between them.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.277-281
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• 2011

A rapid and very sensitive high-performance liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry method to detect ethylenethiourea (ETU) fungicide residues in fruits was developed. Methylene chloride was used as the surface extraction solvent for the target component. Recovery rates improved when cysteine hydrochloride and sodium carbonate were added to product prior to fortification. The limits of detection and quantification were approximately 0.006 and 0.02 mg/kg, respectively, from mandarin oranges. Recoveries from mandarin oranges, oranges, bananas, and pears, spiked in the range of 0.05-0.5 mg/kg, averaged 80-100%. The proposed method was used to monitor the presence of ETU in commercial fruits purchased from different markets in Seoul, Korea. ETU was found in four orange peels and in three mandarin orange peel samples. The highest ETU residue levels were $73.6{\mu}g/kg$ and $29.8{\mu}g/kg$.