• Journal of the Korean Chemical Society
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• v.59 no.3
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• pp.225-232
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• 2015

A liquid chromatography-electrospray ionization-tandem mass spectrometry method (LC-ESI-MS/MS) was used for determining seven pesticides (2,4-dichlorophenoxyacetic acid, methomyl, aldicarb, 2-methyl- 4-chlorophenoxy- acetic acid, molinate, carbaryl and carbofuran) and two synthetic materials (quinoline and bisphenol-A) in surface water. The analytes were extracted using solid-phase extraction (SPE). The eluate was concentrated by nitrogen gas. 100 microliters of 30% (v/v) methanol aqueous solution were used to dissolve the residue and an aliquot of the reconstituted solution was directly injected into LC-ESI-MS/MS after the filtration using 0.2 μm polytetrafluoroethylene (PTFE) syringe filter. Under the established condition, the calibration curves of the analytes were linear with correlation coefficients of above 0.997. The quantification limit was 0.002~0.011 μg/L and the relative standard deviations were less than 16.4%. In addition, accuracy was in the range of 84~107% and the recoveries were values between 56.2 and 98.6%. In this study, the developed method was applied to the analysis of real surface water samples.

• Analytical Science and Technology
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• v.19 no.4
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• pp.290-300
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• 2006

Disinfection by-products(DBPs), such as volatile trihalomethanes and the nonvolatile organochlorine acids, created by chlorination have been extensively studied. However MX which contributes 20-50% of the mutagenic activity in drinking water began to people's attention since 1990. Its chemical name is 3-chloro-4-dichloromethyl-5-hydroxy-2(5H)-furanone. According to WHO guidelines its concentration should be controlled, but its value has not been set up. Due to analytical difficulties in measuring this compound at such a low concentrations and lack of information on toxicity to human. Because concentration (ng/L) of MX in drinking water is low traditional testing methods are ineffective. Therefore this study compared LLE and SPE and have chosen SPE to improve preconcentration. MX has been identified in chlorinated drinking water samples in several countries but not in korea Therefore this study analyzed concentration of MX in different water sources and in spring water. This study examined the causes of changing MX content. Chlorine dosage, seasons, water temperature and distance from the source was all discoverd to be relavant. MX was analyzed in various treatment to find optimum disinfection methods. The outcome was that the concentration of MX was minimized when using biological activated carbon-O3 and granular activated carbon.

• 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.

• Korean Journal of Pharmacognosy
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• v.43 no.3
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• pp.250-256
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• 2012

In order to extract the curcuminoid such as curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) in turmeric (Curcuma longa), solvent extraction methods (dipping and ultrasonic extraction method) and solid-phase extraction (SPE) were used. RP-HPLC (reverse-phase high-performance liquid chromatography) and TLC (thin-layer chromatography) were used for identification and analysis the three curcuminoid. From the experimental results, it is evident that the percentage of curcuminoid extracted from turmeric by ultrasonic extraction method was higher than dipping method. The percentage of curcumin extracted from turmeric by pure methanol was higher than any aqueous methanolic composition. Moreover, the total peak area of three curcuminoid was above 92% in RP-HPLC using solid-phase extraction. These results will form a database for investigating the constituents of natural products and the resources of pharmaceutical, nutrition, and cosmetic products.

• Journal of the Korean Chemical Society
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• v.45 no.2
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• pp.149-155
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• 2001

A new analytical method of cyanobacterial toxins, i, e, microcysins was deveeloped using supercritical fluid extraction(SFE). The microcystins mcluded in the study are sparsely soluble in neat supercritical fluid CO$_2$ However, the microcystins were successfully extracted with a temary mixture(90% CO$_2$,9.0% methanol 1.0% water) at 40$^{\circ}$C and 250 atm. The SFE method developed in this study has several advantages over solid-phase extraction(SPE) sample preparation for the analysis of microcystins. Sample handling steps are minimized thus reducing possible losses of analytes and saving analysis time. No clean-up steps are employed in this SFE method. Althouhgh many methods have been described for microcystim RR and LR, the method using solid-phase extraction with ODS cartridges is the most commonly used. However, the adsorbing power of ODS caridges for microcystins is weak, so we have attempted to use a more polar CN cartridge, to increase the adsorbing power for microcystins. Lyophilized cells(100mg) were wxtracted with 5% (v/v) acetic acid. The extract was centrifuged and then the supernatant was applied to a CN cartridge. The cartridge which contained microcystins was rinsed with 5 ml of water and 5 ml of 0.5 M acetic acid. followed by 5 ml of 5% acetonitrile in water , and were determined by HPLC. Better recoveries and chromatogram were observed than with ODS cartridge.

• Journal of the Korean Chemical Society
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• v.37 no.6
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• pp.590-598
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• 1993

The simultaneous analysis of samples, 16 organic pesticides in water among 129 priority pollutants listed by EPA, was performed by GC-ECD (electron capture detector) and GC/MS-SIM (selected ion monitoring). Two extraction procedures, liquid-liquid extraction (LLE) and solid-phase extraction (SPE), were studied as an extraction and concentration method. Accuracy and precision of the methods were measured by the calculation of mean recovery and mean relative standard deviation. Finally, the detection limits, the experimental limitations, and prospects were discussed.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.970-975
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• 2005

Based on their biological activity, phenols from rosemary extract were evaluated for inhibition of Helicobacter pylori. Contents of total phenolic compounds and inhibition zone of water and ethanol extracts from rosemary were 24.3mg/g and 25.7mg/g, and 11mm, 14mm, and, at $200{\mu}g/mL$ phenol content, 20.9% and 78.2% inhibitory activities were observed, respectively. Electron donating abilities and 2.2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid cation radicals of water and ethanol extracts were 89.1% and 62.0% and 98.4% and 96.5%, respectively. Thiobarbituric acid reactive substances values of all extracts were lower than that of control. Ethanol extract showed 98.8% angiotensin-converting enzyme inhibitory activity. Xanthin oxidase inhibitory activities of water and ethanol extracts were very high, at 84.8%, 100%, respectively. These results indicated phenolic compounds from rosemary can be utilize as a potential antioxidant, antimicrobial, anti-hypertension and anti-gout sources.

• Analytical Science and Technology
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• v.11 no.4
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• pp.281-291
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• 1998

An analytical method for the simultaneous measurement of trace Cu, Sn, and Bi in blood and urine has been investigated by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Microwave oven was used for the pretreatment of blood samples using nitric acid and hydrogen peroxide in a closedvessel digestion system with 1 mL whole blood for 8 minutes. Amberlite IRC-718 resin was used as a solid phase in solid-liquid extraction technique for the removal of matrix interferences such as Na, S, P, and other polyatomic ion species. Detection limits for Cu, Sn, and Bi by this method were 0.000375 ng/mL, 0.000297 ng/mL, and 0.000174 ng/mL, respectively. Recoveries of 99.1% for Cu, 102.5% for Sn, and 98.4% for Bi were obtained for the standard spiked NIST SRM 955a blood sample. The developed method was applied for whole real blood and urine samples.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.75-83
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• 2013

We applied a sensitive method based on on-line solid-phase extraction (SPE) and liquid chromatography/mass spectrometry (LC/MSD) using an electrospray interface for the determination of eleven perfluorinated compounds (PFCs) in water. The on-line connection suppressed the target loss by keeping the cartridge from drying, which resulted in improvement of the recovery and saving of the analytical time. For the on-line solid-phase extraction of 10 mL water samples, recoveries were between $80.4{\pm}5.2%{\sim}109.5{\pm}1.4%$ and limit of quantification (LOQ) were 3.6~15.9 ng/L for the PFCs. The total PFCs concentrations of the tributaries and main stream of Nakdong River water samples were in the range of $8.0{\sim}678.6{\mu}g/L$.

• Analytical Science and Technology
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• v.22 no.4
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• pp.319-325
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• 2009

An effective and specific procedure for confirmation of neomycin, aminoglycoside antibiotic in honey was developed and validated. Honey was adjusted to pH 2 with 0.1M HCl and applied to weak cation-exchange SPE cartridge. Neomycin was eluted with basified methanol. Following separation by ion-pairing liquid chromatography, neomycin was analysed with positive electrospray ionization and MRM mode. Quantification was linear over the range of $5.0{\sim}250.0{\mu}g/kg$ ($r^2$ >0.9951). The precision (R.S.D.) and accuracy (as a bias) of quality control samples in honey ranged 11.5~18.7% and 10.9~20.9%, respectively. Established method can be applied to analysis of neomycin in honey.