• Archives of Pharmacal Research
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• v.22 no.2
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• pp.189-193
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• 1999

Reversed-phase high-performance liquid chromatography/mass spectrometry (HPLC/MS) with an eletcrospray ionization (ESI) interface was applied to the identification of metabolites of IY81149 in the rat plasma. Fragments obtained using collision-induced dissociation (CID) in both positive and negative modes were utilized to elucidate the structure of metabolites. The eluent from the conventional HPLC column was split and directly introduced into an ESI-mass spectrometer for the identification of the structures. the CID technique allowed the sensitive identification of sulfonyl-IY81149 and hydroxy-IY81149 from the rat plasma.

• Journal of Applied Biological Chemistry
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• v.56 no.1
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• pp.43-48
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• 2013

In this study, methanol extracts from 25 indigenous Korean corals were prepared and their carotenoid constituents were analyzed by high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (HPLC-APCI-MS). Among them, extracts from nine species showed detectable peaks in the HPLC chromatogram at 450 nm and the ultraviolet/visible spectra exhibiting carotenoid-specific characteristics were chosen. The mass data of carotenoid peaks revealed that only peridinin could be identified based on literature comparison and suggested the potential presence of novel carotenoid structures. This is the first reported investigation of indigenous Korean coral carotenoids and further work is needed to explore the carotenoids and their potential roles in the ecosystem of indigenous Korean corals.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1221-1227
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• 2011

Ethyl pyruvate (EP) is known as a scavenger of reactive oxygen species (ROS) in the body through its role in the donation of diketone groups to metals to form an EP-metal complex. In order to develop a method for the quantification of EP in biological media, a sensitive and specific, high-performance liquid chromatographyelectrospray ionization-mass spectrometry (HPLC-ESI/MS) method is used to determine the EP-alkali metal ion binding species. The analyte was separated on a ZORBOX SB-C8 ($3.5{\mu}m$, $30mm{\times}2.1mm$ I.D.) column and analyzed in selected ion monitoring (SIM) mode with a positive ESI interface using the m/z 255 $[2M + Na]^+$ ion. The method was validated over the concentration range of $0.5-60.0\;{\mu}g$/mL under 1/9 (v/v) of acetonitrile/methanol solvent system with flow rate 0.05 mL/min. The limit of quantification (LOQ) was $0.5{\mu}g$/mL.

• Proceedings of the Korean Society of Toxicology Conference
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• 2006.11a
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• pp.65-74
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• 2006

Modem drug discovery requires rapid pharmacokinetic evaluation of chemically diverse compounds for early candidate selection. This demands the development of analytical methods that offer high-throughput of samples. Naturally, liquid chromatography / tandem mass spectrometry (LC-MS/MS) is choice of the analytical method because of its superior sensitivity and selectivity. As a result of the short analysis time(typically 3-5min) by LC-MS/MS, sample preparation has become the rate- determining step in the whole analytical cycle. Consequently tremendous efforts are being made to speed up and automate this step. In a typical automated 96-well SPE(solid-phase extraction) procedure, plasma samples are transferred to the 96-well SPE plate, internal standard and aqueous buffer solutions are added and then vacuum is applied using the robotic liquid handling system. It takes only 20-90 min to process 96 samples by automated SPE and the analyst is physically occupied for only approximately 10 min. Recently, the ultra-high flow rate liquid chromatography (turbulent-flow chromatography)has sparked a huge interest for rapid and direct quantitation of drugs in plasma. There is no sample preparation except for sample aliquotting, internal standard addition and centrifugation. This type of analysis is achieved by using a small diameter column with a large particle size(30-5O ${\mu}$m) and a high flow rate, typically between 3-5 ml/min. Silica-based monolithic HPLC columns contain a novel chromatographic support in which the traditional particulate packing has been replaced with a single, continuous network (monolith) of pcrous silica. The main advantage of such a network is decreased backpressure due to macropores (2 ${\mu}$m) throughout the network. This allows high flow rates, and hence fast analyses that are unattainable with traditional particulate columns. The reduction of particle diameter in HPLC results in increased column efficiency. use of small particles (<2 urn), however, requires p.essu.es beyond the traditional 6,000 psi of conventional pumping devices. Instrumental development in recent years has resulted in pumping devices capable of handling the requirements of columns packed with small particles. The staggered parallel HPLC system consists of four fully independent binary HPLC pumps, a modified auto sampler, and a series of switching and selector valves all controlled by a single computer program. The system improves sample throughput without sacrificing chromatographic separation or data quality. Sample throughput can be increased nearly four-fold without requiring significant changes in current analytical procedures. The process of Bioanalytical Method Validation is required by the FDA to assess and verify the performance of a chronlatographic method prior to its application in sample analysis. The validation should address the selectivity, linearity, accuracy, precision and stability of the method. This presentation will provide all overview of the work required to accomplish a full validation and show how a chromatographic method is suitable for toxirokinetic sample analysis. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method developed to quantitate drug levels in dog plasma will be used as an example of tile process.

• Analytical Science and Technology
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• v.26 no.6
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• pp.357-363
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• 2013

Selenium-containing proteins were separated from selenium-enriched yeast (SEY) using Trizol$^{(R)}$ reagent followed by anion exchange (AE) chromatography. This method is simpler and less time consuming than electrophoresis. Five selenium containing proteins were identified by on-line AE HPLC-ICP/MS (high performance liquid chromatography-inductively coupled plasma/mass spectrometry). Each protein was enzymatically hydrolyzed to seleno-amino acids and separated with RP (reverse phase) HPLC for the identification of selenoproteins.

• Analytical Science and Technology
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• v.36 no.1
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• pp.22-31
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• 2023

As the use of e-liquid cigarettes is rapidly increasing worldwide, it multiplies the potential risk undisclosed to the health of non- and smokers. To reduce the hazard, each country has its own set of regulations for controlling e-liquids. In Korea, the narrow definition of tobacco makes it difficult and have been steadily occurring tax evasion exploiting the difference in natural and artificial nicotine. Therefore, it is very important to distinguish source of nicotine for their regulation. To find biochemical discriminant markers, this study established analysis methods based on high-performance liquid chromatography coupled with diode array detector (HPLC-DAD) and high-performance liquid chromatography coupled with triple Quadrupole mass spectrometry (HPLC-MS/MS) for nicotine enantiomers and tobacco alkaloids targeted using the difference in pathways of nicotine biosynthesis and chemical synthesis. The method was validated by experimenting linearity (R² > 0.999), recovery (80.99-108.41 %), accuracy (94.11-109.73 %) and precision (0.04-8.27 %). Then, the results for discrimination of the nicotine obtained from analysis of 65 commercial e-liquid products available in Korean market was evaluated. The method successfully applied to the e-liquids and one sample labelled 'synthetic nicotine' for tax exemption was found to contain a natural nicotine product. This method can be used to determine whether an e-liquid product uses natural or artificial nicotine and monitor non-taxable e-liquid products. The method is more scientific than the existing one, which relies only on field evidence.

• Korean Journal of Poultry Science
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• v.31 no.3
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• pp.137-143
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• 2004

The fractional synthesis rates(FSR) were measured with 2l-wk and 3l-wk-old broiler breeder pullets and hens to investigate the effect of sexual maturity on FSR. The FSR were obtained from chicken tissues and blood samples using High-Performance Liquid Chromatography/Mass Spectrometry(HPLC/MS). A L-l-13C, 15N -leucine saline solution was infused by bolus injection as a tracer into broiler breeder pullets in the experiment. A rapid HPLC/MS method was developed to measure the isotopic enrichments of leucine in plasma, tissue samples, and eggs. The enrichments of stable isotope leucine incorporated into protein and the enrichments of the stable isotope free leucine were measured in liver, breast muscle and blood samples. Two sets of experiments were conducted. In experiment one, 2l-wk-old, sexually immature broiler breeder pullets were divided into groups of three and blood samples were collected at 20 or 30 min intervals until 1.5 h from initial injection. The pullets were sacrificed in groups of three at varying time intervals for 7 h after injection. The liver, breast muscle and blood samples were removed for analysis. The FSR were estimated to be 8.7l%/day for liver, 4.06％/day for breast muscle, and 5.08％/day for blood samples in 30 minutes after injection from the enrichment ratios. In experiment two, sexually matured 3l-wk-old broiler breeder hens were assorted into groups of three and blood samples were obtained at 20 or 30 min intervals for 2 h. The FSR for blood samples were determined. The broiler breeder hens were sacrificed in groups of three at various time intervals until 7 h after injection and liver, breast muscle and blood samples were removed for analysis. The FSR were calculated to be 5.96％/day for liver. Eggs were collected from five chickens daily for 10 days after large bolus injection. The average of total enrichments of stable isotope in egg albumin was increased by 0.064% at 4 days after injection and was back to normal in 7 days.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1799-1803
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• 2003

The possibility of lycopene affecting egg yolk pigmentation was studied with lycopene diets containing 0, 4, 8, and $12{\mu}g/g$ meal, respectively. The addition of lycopene above $4{\mu}g/g$ meal significantly improved yolk color after four days of supplementation. The transfer of lycopene into egg yolk was confirmed by thin layer chromatography, and high-performance liquid chromatography-mass spectrometry (HPLC-MS). The deposition rate of lycopene into egg yolk was approximately 2%, which was quantitatively determined using a HPLC with a UV detector. The result indicates that lycopene is a good candidate for egg yolk pigmentation and for making functional eggs.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.224-229
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• 2011

Zearalenone (ZEA) is an estrogenic mycotoxin mainly produced by Fusarium graminerum, a species which colonizes a wide variety of cereals, including wheat, barley and processed products. A survey of ZEA contamination was conducted on 141 dried confectioneries, 59 breads and rice cakes, 135 noodles and 101 other products, for a total of 432 commercial samples. Samples were analyzed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) after immunoaffinity clean-up and was confirmed by liquid chromatography tandem mass spectrometry (LCMS/MS). The limits of detection and quantification were 2.0 and $6.0{\mu}g/kg$, respectively. The recovery ranged from 80.2% to 98.4% in the cereal based product. ZEA was detected in 38 samples (8.8% incidence), including 3 snack, 2 biscuit and 33 other cereal products. The ZEA contamination levels were in the range of $5.38-53.76{\mu}g/kg$. Finally, LC-MS/MS analysis of the contaminated samples was conducted to confirm the detected ZEA, and all 38 samples showing ZEA by HPLC-FLD were confirmed by LC-MS/MS.

• Journal of environmental and Sanitary engineering
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• v.22 no.3
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• pp.89-96
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• 2007

To determine 8 anti-impotence drug/drug-like compounds such as sildenafil, vardenafil, tadalafil, homosildenafil, hydroxyhomosildenafil, aminotadalafil, pseudovardenafil and hongdenafil in foods, simultaneously, high performance liquid chromatography(HPLC) and liquid chromatography-mass spectrometry (LC/MS) were used. The HPLC/UV analysis was performed on a column of capcellpak $C_{18}$ with 0.1% sodium-1-hexansulfonate in 0.2M ammonium formate/acetonitrile as a mobile phase. Mass spectra of the compounds by LC/MS were investigated with SCAN mode(Mass range and Fragment voltage) and SIM(Selected Ion Monitoring) mode (Ion target and Fragment voltage). The results follow as; 1. The HPLC/UV analysis was detected from 5 out of 63 samples. The content of sildenafil was in the range of 32.80 ppm ${\sim}$ 60.13 ppm from 4 out of 5 samples. The contents of sildenafil, vardenafil, homosildenafil were in the range 47.14 ppm from 1 out of 5 samples. 2. The conformed result of LC/MS was equal of detected from 5 out of 63 samples in HPLC/UV analysis. An easily available, simultaneous determination of 8 standards in adulterated health related foods was established by using a combination of LC/MS methods.