• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.236-243
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• 1987

The optimum resolution condition of 11 organophosphorus pesticides by gas-liquid chromatography was studied using a capillary column. The injection modes and types of vaporization tubes were evaluated in relation to pesticide analysis. The best reproducibility of peak heights of pesticides was obtained by the split mode with the vaporization tube packed with quartz wool. A 25m SE-30 capillary column provided better resolution than SE-54 column for their optimum resolution. The column at $200^{\circ}C$ initially was heated by $5^{\circ}C/min\;to\;230^{\circ}C$ followed by $10^{\circ}C/min\;to\;270^{\circ}C$ and the temperatures were held constant for 5 minutes at $230^{\circ}C\;and\;270^{\circ}C$, respectively. The relative standard deviations of their retention times were less than 0.19%.

• Analytical Science and Technology
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• v.31 no.1
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• pp.23-30
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• 2018

Twenty-two allergy-induced aromatics in children were analyzed using a gas chromatography flame ionization detector (GC-FID) and gas chromatography mass spectrometer (GC-MSD). Analytes were extracted using an automatic Soxhlet extractor and centrifuged for 10 min in a fast freezing centrifuge, and the supernatant was transferred into a 2 mL vial and injected in split mode. Under the established conditions, the calibration curve showed linearity with a correlation coefficient of 0.996 or more. A wide range of sensitivity of 6.7 to 1,859,839 depending on the device characteristics and detector used was shown. The detection limit of the device was 0.0032 to $0.0335{\mu}g/mL$, and the maximum detection limit was less than $0.1{\mu}g/mL$. The detection limit of the method ranged from 0.0033 to $0.1161{\mu}g/mL$. In addition, the limit of quantification ranged from 0.0100 to $0.5422{\mu}g/mL$, with a level of precision ranging from 0.21 % to 4.89 % and a degree of accuracy ranging from 89 % to 111 %. The analytical method developed in this study was applied to commercial products.

• Analytical Science and Technology
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• v.12 no.5
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• pp.408-414
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• 1999

A selective and sensitive method for the derivatization of total homocysteine (Hcy) and the related compounds in plasma by gas chromatograph (GC)-electron capture detector (ECD) has been developed. To determine total homocysteine, cysteine (Cys), and methionine (Met) in human plasma using GC-ECD, analytes were reduced and converted into their N(O,S)-ethylearbonyl pentafluoropropyl (PFP) ester by derivatization with ethyl chloroformate and pentafluoropropyl alcohol (PFP-OH) in plasma. The best derivatizing agent N(O,S)-ethyl carbonyl PFP ester, was chosen by comparing the sensitivity of derivatized analysis in GC-ECD. The derivatized analytes in plasma were extracted by chloroform, and subsequently back-extracted with hexane and analyzed by GC-ECD. The calibration carves ($R^2$ > 0.990) were linear over the range $5-50{\mu}mol/L$ of Hcy and Met, $40-400{\mu}mol/L$ of Cys spiked in plasma. The detection limit observed by the established method was below $0.5{\mu}mol/L$. This method is highly sensitive and specific in the analysis of Hcy, Cys, and Met. Therefore, we suggest that this method is appropriate in the analysis of trace concentration of Hcy, Cys, and Met in biological fluids.

• Journal of the Korean Chemical Society
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• v.39 no.2
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• pp.94-102
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• 1995

S-Hydroxypropyl(PH) ${\beta}$-cyclodextrin(hydrophilic), dialkyl(DA)-cyclodextrin(hydrophobic), trifluoroacetyl(TA) ${\gamma}$-cyclodextrin(intermediate) stationary phases were used for gas chromatographic separation of racemic alcohols and their derivatives. All the alcohols used for this experiment were derivatived by using trifluoro acetic anhydride, acetic anhydride, or trichloro acetic anhydride. It is apparent that the enantioselectivity of the enantiomeric pairs was very dependent on the type of acylation reagent. The best experimental condition of optical resolution of the alcohols and their derivatives was different on the polarity of the solute molecules. The chiral separation was also studied depending on temperature, polarity of the column, and hydrogen bonding ability and steric effect between the alchols and CD stationary phase. The chiral recognition mechanism is dependent not upon the kinds of the chiral stationay phases but upon the derivatization of the racemic alchols.

• Journal of the Korean Chemical Society
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• v.29 no.5
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• pp.503-509
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• 1985

Sixteen organochlorine pesticides extracted out from the crops and cleaned by solvent-solvent partitioning and Florisil column chromatography were determined by gas-liquid chromatography. The majority of the pesticides were well separated by being eluted through 5% QF-1 column and some of them through 3% OV-17 column and 2.596 DC-200/2.5% QF-1 column, and the eluted pesticides were detected by $^{63}Ni$ electron capture detector. The linear calibration curves were obtained for the most of pesticides while some curves were slightly deviated from the linearity. In the determination of 16 pesticides added to thirteen kinds of crops, the recoveries were showed over 85% for the most cases and the relative standard deviations of 5 analyses were less than 12.1%. The results were within the criteria of the AOAC method.

• Journal of the Korean Chemical Society
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• v.41 no.9
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• pp.471-482
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• 1997

GC/MS was used to find an optimum experimental condition for the screening of organic acids in urine. Urinary organic acids were isolated through the liquid-liquid extraction method (LLE) to examine the influence of pH and the effect of including the back extraction and oximation processes respectively on the extraction. When pH was adjusted to 0.5 during the extraction without oximation process, relatively higher recovery rate and the smallest relative standard deviations (0.3-12.4%) were obtained. By removing the interference, the addition of back extraction made possible surer identification of organic acids with retention time of 15-16 minutes. Under this condition, we obtained the content distribution of urinary organic acids in healthy Korean children (n=16) by establishing the calibration curves for 51 standard organic acids.

• Analytical Science and Technology
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• v.9 no.2
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• pp.123-133
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• 1996

The optimum conditions for the analysis of the difenoconazole fungicide on soil and crops were investigated and the residues of that in apple and soil were identified by using the gas chromatography. The extract with acetonitrile was separated with saturated NaCl and n-hexane solution after filtered, and concentrated. Obtained fungicide residues were transfered to the florisil column and eluted with acetone and n-hexane mixed solution for the analysis by GLC(ECD). From the standard addition experiments with 0.20 and 1.0ppm, the average recoveries were 86~92% and the detection limit was 0.01 ppm. It seems to be safely used when difenoconazole is treated three times until 15 days before harvest of apple. In this case residual amounts of difenoconazole in apple was from 0.037ppm to 0.044ppm. The soil samples extracted with methanol and ammonium hydroxide mixed solution were partitioned with dichloromethane and saturated sodium chloride solution. The organic phase was concentrated and redissolved with toluene and analyzed with GLC(FID) after cleaned with Sep-Pak column. From the standard addition experiments with 0.10, 0.50 and 1.0ppm, the average recoveries were 101.2~103.7% and the detection limit was 0.025ppm.

• Journal of the Korean Chemical Society
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• v.45 no.5
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• pp.422-428
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• 2001

Retention relative times(RRTs) of PAH molecules and their derivatives in gas chromatography are trained and predicted in testing sets using a multiple linear regression(MLR) and an artificial neural network(ANN). The main descriptors of PAHs and their derivatives in QSRR are the square root of molecular weight(sqmw), molecular connectivity($^1{\chi}_v$), molecular dipole moment(D) and length-to-breadth ratios(L/B). The results of MLR shows that a heavy molecule has a propensity for long retention time. L/B closely related with slot model is a good descriptor in MLR. On the other hand, ANN which is not effected by the linear dependencies among the descriptors were exclusively based on molecular weight and molecular dipole moment. The variances which shows the accuracy of prediction for retention times in testing sets are 1.860, 0.206 for MLR and ANN, respectively. It was shown that ANN can exceed the MLR in prediction accuracy.

• Industry Promotion Research
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• v.9 no.1
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• pp.13-20
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• 2024

In this study, we conducted a compositional analysis of five darkening shampoos available in the South Korean market and evaluated their active ingredients and safety based on the analysis results. GC-MS analysis was employed to identify the main components of each shampoo, revealing discrepancies between the detected compounds and the ingredient lists provided by the manufacturers. These differences are interpreted as being due to the limitations of the GC-MS analysis and the volatility of certain compounds. Further investigations were carried out to explore compounds potentially contributing to hair darkening. However, it was not definitively concluded that these compounds are directly involved in the hair darkening process. It is speculated that they may enhance hair care product performance and offer additional benefits to hair, or improve product texture, stability, or preservation. Additionally, the GC-MS analysis identified several compounds with potential safety concerns, necessitating caution when used as cosmetic ingredients.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.311-318
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• 2015

This work investigated the plasma treatment of aqueous bisphenol A (BPA) solution and mineralization pathways. For the effective contact between plasmatic gas and aqueous BPA solution, the plasma was created inside a porous ceramic tube, which was uniformly dispersed into the aqueous solution through micro-pores of the ceramic tube. Effects of the gas flow rate, applied voltage and treatment time on the decomposition of BPA were examined, and analyses using ultraviolet (UV) spectroscopy, ion chromatography and gas chromatography-mass spectrometry were also performed to elucidate mineralization mechanisms. The appropriate gas flow rate was around $1.0L\;min^{-1}$; when the gas flow rate was too high or too low, the BPA decomposition performance at a given electric power decreased. The increase in the voltage improves the BPA decomposition due to the increased electric power, but the energy required to remove BPA was similar, regardless of the voltage. Under the condition of $1.0L\;min^{-1}$ and 20.8 kV, BPA at an initial concentration of $10L\;min^{-1}$ (volume : 1 L) was successfully treated within 30 min. The intermediates produced by the attack of ozone and hydroxyl radicals on BPA were further oxidized to stable compounds such as acetate, formate and oxalate.