• Journal of the Korean GEO-environmental Society
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• v.11 no.5
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• pp.61-67
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• 2010

In this study, Solid-phase microextraction (SPME) with GC/FID was studied as a possible alternative to liquid-liquid extraction for the analysis of chlorinated solvents (PCE and TCE) and these by-products (cis-DCE, VC, and Ethylene). Experimental parameters affecting the SPME process (such as kind of fibers, adsorption time, desorption time, volume ratio of sample to headspace, salt addition, and magnetic stirring) were optimized. Experimental parameters such as CAR/PDMS, adsorption time of 20 min, desorption time of 5 min at $250^{\circ}C$, headspace volume of 50mL, sodium chloride (NaCl) concentration of 25% combined with magnetic stirring were selected in optimal experimental conditions for analysis of chlorinated solvents and these by-products. The general affinity of analytes to CAR/PDMS fiber was high in the order PCE>TCE>cis-DCE>VC>Ethylene. The linearity of $R^2$ for chlorinated solvents and these by-products was from 0.912 to 0.999 when analyte concentrations range from $10{\mu}g/L$ to $500{\mu}g/L$, respectively. The relative standard deviation (% RSD) were from 2.1% to 3.6% for concentration of $500{\mu}g/L$ (n=5), respectively. Finally, the limited of detection (LOD) observed in our study for chlorinated solvents and these by-products were from $0.5{\mu}g/L$ to $10{\mu}g/L$, respectively.

• Analytical Science and Technology
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• v.14 no.1
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• pp.44-49
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• 2001

Solid-phase microextraction (SPME) with $85{\mu}m$ polyacrylate fiber, coupled to gas chromatography-mass spectrometry was used to analyze the plasticizers contained in balloon samples. The balloons were identified to be made of polyisoprene by IR spectroscopy. The plasticizers extracted from the balloon samples soaked in acetone-added water solvent for an hour were quantified by external standard method using nine kinds of plasticizers. The quantification method was validated for standard plasticizers in the range of $0.25-25{\mu}g/g$. The detection limits were $0.11-0.38{\mu}g/g$ for different plasticizers. The RSDs for the reproducibility of this quantitation method were 3.7-14.2%. A few of balloons included risky level of plasticizer concerned as and endocrine disrupter, and it is necessary to regulate these products.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.35-43
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• 2006

Formaldehyde is important because of their irritant and toxic properties, mutagenicity and carcinogenicity. In this study, liquid chromatography-mass spectrometry (LC-MS) is used for the analysis of formaldehyde after derivatization with 2,4-dinitrophenylhydrazine (DNPH) cartridge. Analytical parameters such as linearity, repeatability and minimum detection limit were evaluated. The linearity ($r^2$) was 0.9997 when analyte concentration ranges from 25 to $200{\mu}g/l$. The relative standard deviation (%RSD) was 1.25 % for concentration of $200{\mu}g/l$. The minimum detection limit (MDL) was 0.73 ppbv. It was shown that LC-MS method has a great potential for formaldehyde analysis. The results of formaldehyde from the survey of Ban-Woll and Shi-Hwa Industrial Complex samples, the highest level was 6.20, 3.93 ppb, respectively. The highest emission level of formaldehyde at chemical plants in the Ban-Woll' Shi-Hwa Industrial Complex was 5421.25 ppb.

• Journal of Food Hygiene and Safety
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• v.31 no.2
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• pp.94-98
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• 2016

This study was conducted to establish the simultaneous analysis method for veterinary drug residues in honey by high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS). The eleven targeting veterinary drugs with honey test method in Korean Food Standards Codex were divided into Group 1 (streptomycine dihydrostreptomycine, neomycine) and Group 2 (oxytetracycline, enrofloxacin, ciprofloxacin, cymiazole, chloramphenicol, amitraz, coumaphos, fluvalinate) to be analyzed simultaneously. From the results, the retention time (RT) of the targeting drugs was within 15 min, the range of detection limits was 0.0056 to $0.0643{\mu}g/g$ and the range of quantification limits was 0.0169 to $0.1948{\mu}g/g$. The coefficients of determination ($R^2$) for Group 1 ($0.05{\sim}1.0{\mu}g/mL$) and Group 2 ($0.01{\sim}1.0{\mu}g/mL$) were 0.9917~0.9987 and 0.9923~1.000 respectively, and showed the good linearity. The recovery rates for Group 1 (final conc. $0.25{\mu}g/g$) and Group 2 (final conc. $1.0{\mu}g/g$) were 65.1~80.6% and 64.2~90.3% respectively. Also, the analysis results of inter day (n = 3) and intra day (n = 6) RSD (%) for area and retention time showed that the RSD (%) for area and retention time was below 10.92% and 1.57%. Therefore, the simultaneous analysis method of this study is evaluated to be a good test method for veterinary drug residues in honey.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.4
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• pp.459-464
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• 2017

Biphenyl is used as an intermediate in the production of crop protection products, a solvent in pharmaceutical production, and as a component in the preservation of citrus fruits in many countries. Biphenyl is not authorized for use and also does not have standards or specifications as a food additive in Korea. National and imported food products are likely to contain biphenyl. Therefore, control and management of these products is required. In this study, a simple analytical method was developed and validated using HPLC to determine biphenyl in food. These methods are validated by assessing certain performance parameters: linearity, accuracy, precision, recovery, limit of detection (LOD), and limit of quantitation (LOQ). The calibration curve was obtained from 1.0 to $100.0{\mu}g/mL$ with satisfactory relative standard deviations (RSD) of 0.999 in the representative sample (orange). In the measurement of quality control (QC) samples, accuracy was in the range of 95.8~104.0% within normal values. The inter-day and inter-day precision values were less than 2.4% RSD in the measurement of QC samples. Recoveries of biphenyl from spiked orange samples ranged from 92.7 to 99.4% with RSD between 0.7 and 1.7% at levels of 10, 50, and $100{\mu}g/mL$. The LOD and LOQ were determined to be 0.04 and $0.13{\mu}g/mL$, respectively. These results show that the developed method is appropriate for biphenyl identification and can be used to examine the safety of citrus fruits and surface treatments containing biphenyl residues.

• Journal of Pharmaceutical Investigation
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• v.41 no.1
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• pp.25-30
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• 2011

Recently, Korean Food and Drug Administration (KFDA) has focused on developing quality control guidelines for all commercial products in Korea to enforce regulations, improve the quality control, and protect consumers by developing prevalently used and efficient analytical tools to determine and quantify target compounds. Because the Korean Pharmacopeia (KP) presents microbiological assays for biotin, which is laborious and time-consuming, this study is focused on applying HPLC-UV to detect and quantify biotin in complex drugs and dietary supplements like multi-vitamin. Biotin in complex drugs was extracted from methanol and analyzed using mobile phase with 10 mM potassium phosphate (monobasic, pH=3.0) in distilled water and acetonitrile. Gradient condition was used to successfully detect and quantify biotin within 20 minutes. Validation result for linearity was significant that average $r^2$ was 0.999 (n=3) and its relative standard deviation (RSD) was 0.0578% which was less than 2%. Using this method, quantification of biotin in complex drugs was completed successfully and recovery tests were finished that recovery percentage greater than 95% with relative standard deviation less than 2%.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.2
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• pp.201-208
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• 2006

Several carbonyl compounds are important because of their irritant and toxic properties, mutagenicity and carcinogenicity. Therefore, they are regulated in korean odor emission standard. In this study, atmospheric pressure ionization-mass spectrometry(API-MS) is used for the analysis of carbonyl compounds after derivatization with 2, 4-dinitrophenylhydrazine (DNPH) and liquid chromatographic separation. In the negative ion mode, the $[M-H]^-$ pseudomolecular ions are most abundant for the carbonyls. Analytical parameters such as linearity, repeatability and minimum detection limit were evaluated. The linearities ($r^2$) for carbonyls were $0.9977{\sim}0.9999$ when analyte concentration ranges from $25\;to\;250{\mu}g/L$(n=6). The relative standard deviations (%RSD) for carbonyls were $0.55{\sim}3.51%$ for concentration of $100{\mu}g/L$(n=5). The minimum detection limit (MDL) was $1.88{\mu}g/L$(0.27 ppb) for i-valeraldehyde. It was shown that LC-MS method has a great potential for carbonyl compounds analysis.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1297-1302
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• 2012

The interaction between carbon monoxide (CO) and a cobalt-salen complex (Co(salen)) was studied and applied to detect CO. The metal complex doped PEDOT:PSS film exhibited good sensitivity to CO and differentiate CO from other gases. The response of the composite to CO was reversible (RSD < 5%) change in resistance upon removal of CO gas from the test chamber. The effects of adding Co(salen) in the probe film on the response of the sensor were investigated using AFM, XPS, and FT-IR spectroscopy. The sensitivity of the sensor increased as the Co(salen) concentration enhanced as it increased from 0.0 to 1.5 wt. %, where the highest sensitivity ($%{\Delta}R/R_o$) of $-25.0{\pm}0.05%$ was achieved with 1.0 wt. % Co(salen). The sensor containing probe exhibited a linear response ($R^2$ = 0.983) in the range of 0.5 to 10.0% CO (v/v) $N_2$, and the detection limit was 1.74% CO (v/v) in $N_2$.

• Natural Product Sciences
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• v.22 no.2
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• pp.77-81
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• 2016

A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of three antibacterial flavonoids, artocarpanone, artocarpin, and cycloartocarpin in ethyl acetate extracts from Artocarpus heterophyllus heartwoods. Separation was achieved using a TSK-gel ODS-80Tm column ($5{\mu}m$, $4.6{\times}150mm$) at $25^{\circ}C$ with a gradient elution system of methanol and water as follows: 0-8 min, 60:40; 8-27 min, 80:20; 27-35 min, 60:40, v/v, at a flow rate of 1 mL/min, and a quantitative UV detection at 285 nm. The method was validated by measuring the key parameters, including specificity, linearity, sensitivity, accuracy, repeatability and reproducibility. A high degree of specificity and sensitivity was achieved. The calibration curves for all three flavonoids showed good linearity with a coefficient of determinations ($R^2$) of ${\geq}0.9995$. The recoveries of the method were from 98-104%, with good reproducibility and repeatability (RSD values of less than 2%) were also achieved. Ethyl acetate was the best solvent for extraction of these three flavonoids using the heat reflux conditions for 1 h. This optimized sample preparation and HPLC method can be practically used for a routine standardization process of the extracts from the A. heterophyllus heartwoods.

• Analytical Science and Technology
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• v.35 no.5
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• pp.218-227
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• 2022

A simple and fast throughput flow injection (FI) system with a merging-zone technique was designed to determine ferrous and ferric in an aqueous solution. The method is based on the direct reaction of ferrous with a Bathophenanthroline reagent (Bphen) in acidic media. The forming red complex absorbs light at 533 nm. All conditions of the flow injection system were investigated. The analytical curve of ferrous was linear in the range of 0.07 to 4 mg/L with an r² value of 0.9968. The detection and quantification limits were 0.02 and 0.04 mg/L, respectively. The molar absorptivity and Sandell's sensitivity were 4.0577 × 10⁶ L/mol cm and 25 × 10^-5 ㎍/cm², respectively. The homemade valve was low-cost with high repeatability (n = 7) at an RSD of 1.26 % and zero dead volume. The values of the dispersion coefficient were 2.318, 2.022, and 1.636 for the concentrations of 0.2, 1, and 3 mg/L, respectively. The analysis throughput of the designed flow injection unit was 57 sample per hour.