• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.387-395
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.309-317
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• 2015

BACKGROUND: An analytical method was developed using GC-ECD/MS to precisely determine the residue of fipronil, a phenylpyrazole insecticide used to control a wide range of foliar and soil-borne pests.METHOD AND RESULTS: Fipronil residue was extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, Kimchi cabbage, green pepper, and apple. The extract was diluted with saline water, and fipronil was partitioned into n-hexane/dichloromethane (20/80, v/v) to remove polar co-extractives in the aqueous phase. Florisil column chromatography was additionally employed for final purification of the extract. Fipronil was separated and quantitated by GC-ECD using a DB-17 capillary column. Accuracy of the proposed method was validated by the recovery from crop samples fortified with fipronil at 3 levels per crop in each triplication.CONCLUSION: Mean recoveries ranged from 86.6% to 106.0% in five representative agricultural commodities. The coefficients of variation were less than 10%. Limit of quantitation of fipronil was 0.004 mg/kg as verified by the recovery experiment. A confirmatory technique using GC/MS with selected-ion monitoring was also provided to clearly identify the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of fipronil in agricultural commodities.

• Journal of Ginseng Research
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• v.20 no.3
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• pp.284-290
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• 1996

To Identify phenolic components known to exist in Korean ginseng (Panax ginseng C.A. Meyer) by GC/MS, three derivatization methods were employed for their analyses. First, phenolic components in ether soluble acidic fraction prepared from Korean red ginseng powder were taimethylsilylated. Secondly, phenolic acids in the same fraction were esterified with diazomethane followed by trlmethylsilylation. Thirdly, acidic components in ginseng powder were extracted and esterified concurrently by methanolic sulfuric acid, followed by fractionation of phenolic components with Silica Sep-Paka and trimethylsilylatlon. All phenolic components found in ginseng except gen tisic acid were identified by retention times and mass spectrums of standards. Besides, 5 phenolic components including salicyl alcohol and 1-H-indole-2-carboxylic acid were first identified from Korea an red ginseng by GC/MS.

• Toxicological Research
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• v.7 no.1
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• pp.29-35
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• 1991

Barbiturates are commonly abused tranquilizer and a rapid method to determine these drugs in biological samples is needed. In this study, was screened barbiturates in urine specimens by the fluorescence polarization immunoassay method(FPIA) and the positive samples were confirmed and identified by the more definitive GC/MS method. Fifteen positive smples which have barbiturate values higher than 0.5 ng/ml were analyzed by the GC/MS method. Eight samples were identified as phenobarbital and five samples were identified as crotilbarbitone.

• Journal of Food Hygiene and Safety
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• v.14 no.2
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• pp.140-145
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• 1999

Analytical method for preservatives in food was developed using gas chromatography/mass spectrometry (GC/MS). Propionic acid, sorbic acid, benzoic acid, ethyl salicylate, ethyl p-hydroxy benzoate, iso-propyl p-hydroxy benzoate, n-propyl p-hydroxy benzoate, iso-butyl p-hydroxy benzoate, n-butyl p-hydroxy benzoate, p-hydroxy benzoic acid and dehydro acetic acid were extracted from cooling beverage with diethyl ether. The polar hydroxyl and carboxyl groups of food preservatives were derivatized with N-methyl-N-tert-butyldimethylisilyl-trifluoroscetamide (MTBSTFA) to form the corresponding tert-bytyldimethyl-silylated derivatives, and submitted to GC/MS analysis. The mass spectra of the derivatives were investigated for the selection of monitoring ions for multi-residue analysis of 11 preservatives by GC/MS. The macro program was also developed for the qualitative analysis of these preservatives in food.

• Analytical Science and Technology
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• v.26 no.1
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• pp.80-85
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• 2013

The sixty nine accident preparedness substances (APS) having high probability of chemical accident are controlled under the Toxic Chemicals Control Act (TCCA). Around the world, there has been a growing interest in the analysis of chemical warfare agent (CWAs). When a chemical accident occurs, it is generally required to detect and identify APS. However, the quantitative analytical data remain limited in Korea. In this study, an analytical method using GC/MS for volatile organic chemicals was established and a quantitative analysis method was studied. The calibration curve for 25 chemicals were obtained and 21 chemicals showed higher coefficient of determination ($r^2$ >0.998).

• YAKHAK HOEJI
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• v.26 no.2
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• pp.129-132
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• 1982

A GC/MS method was developed to analyze phenolic acid extract from tobacco leaf. Extracted acids were converted to their methyl esters by refluxing with 3M hydrogen chloride in methanol, and the esters were reacted with his (trimethylsilyl) trifluoroacetamide plus 10% trimethylchlorosilane to silylate the phenolic groups. Derivatives of standard salicylic, p-hydroxybenzoic, vanillic, gentisic, p-coumaric, syringic, ferulic, and sinapic acids prepared by this procedure were analyzed by GC/MS on $20m{\times}0.2mm$ column of SE-54 glass capillary. GC/MS analysis of the extract from tobacco leaf revealed the presence of salicylic, p-hydtoxybenzoic, vanillic, gentisic, protocatechuic, p-coumaric, syringic, gallic, ferulic, caffeic, sinapic, and quinic acids, respectively. The quantitative analysis of these phenolic acids were achieved by using multiple ion selection technique.

• Analytical Science and Technology
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• v.19 no.1
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• pp.107-114
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• 2006

Early diagnosis and medical intervention are critical for the treatment of patients with metabolic disorders. A rapid analytical method was developed for simultaneous quantification of organic acids and amino acids in urine without labor-intensive pre-extraction procedure showing high sensitivity and specificity. A new method consisted of simple two-step trimethylsilyl (TMS)-trifluoroacetyl (TFA) derivatization using GC/MS-selective ion monitoring (SIM). Filter paper urine specimens were dried under nitrogen after being fortified with internal standard (tropate) in a mixture of distilled water and methanol. Methyl orange was added to the residue as indicator reagent. Silyl derivative of carboxylic functional group was followed by trifluoroacetyl derivative for amino functional group. N-methyl-N-(trimethylsilyl-trifluoroacetamide) and N-methyl-bistrifluoroacetamide were consecutively added and heated for 15-20 min at $65^{\circ}C-70^{\circ}C$, for TMS-TFA derivative, respectively. This reactant was analyzed by GC/MS-SIM. Linear dynamic range showed 0.001-50 mg with the detection limit of (S/N=3) 10-200 ng, and the quantification limit of 80-900 ng in urine. Correlation coefficient of regression line was 0.994-0.998. When the method was applied to the patients 'urine, it clearly differentiated the normal from the patient with metabolic disorder. The study showed that the developed method could be the method of choices in rapid and sensitive screening for organic aciduria and amino acidopathy.

• Journal of Applied Biological Chemistry
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• v.63 no.1
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• pp.29-33
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• 2020

The objective of this study was to develop a fast and accurate method of variety discrimination and geographical discrimination origin of Korean angelica (Korean variety, Angelica gigas Nakai) by using TDU-GC/MS. Two peaks of decursin and decursinol, which are coumarin derivatives were identified in the range of Total Ion Chromatogram (TIC) RT 26.9-27.2 of the Korean angelica by GC/MS analysis at the time of condensation in a refrigerated condensation system after thermal desorption of sample extracts. In case of Chinese angelica (Chinese variety), ligustilide peak was detected at the RT 17.2. In order to investigate the difference of volatile components according to the geographical origin of Korean variety, the mass spectra were measured by TDU-GC/MS at the range of m/z 40-400 amu. The TIC of domestic cultivation and Chinese cultivation of the Korean variety, Angelica gigas Nakai showed the same tendency as a whole. However, in partial scans of TIC, two peaks detected at 15.54 and 16.05 of RT showed different peak patterns between Korean angelica (Korean variety) cultivated in Korea and in China. The ratio of Peak A (RT 15.54) and B (RT 16.05) was 0.0-0.2 for domestic cultivation and 0.5-2.8 for Chinese cultivation, confirming the possibility of discriminating origin by comparing the TIC peak pattern of TDU-GC/MS.

• Analytical Science and Technology
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• v.33 no.1
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• pp.23-32
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• 2020

Methamphetamine (MA) is the most common and available drug of abuse in Korea and its primary metabolite is amphetamine (AP). Detection of AP derivatives, such as MA, AP, phentermine (PT), MDA, MDMA, and MDEA by the use of immunoassay screening is not reliable and accurate due to cross-reactivity and insufficient specificity/sensitivity. Therefore, the analytical process accepted by most urine drug-testing programs employs the two-step method with an initial screening test followed by a more specific confirmatory test if the specimen screens positive. In this study, a gas chromatography-mass spectrometric (GC-MS) method was developed and validated for confirmation of MA and AP in human urine. Urine sample (500 µL) was added with N-isopropylbenzylamine as internal standard and ethyl chloroformate as a derivatization reagent, and then extracted with 200 µL of ethyl acetate. Extracted samples were analysed with GC-MS in the SIM/ Scan mode, which were screened by Cobas c311 analyzer (Roche/Hitachi) to evaluate the efficiency as well as the compatibility of the GC-MS method. Qualitative method validation requirements for selectivity, limit of detection (LOD), precision, accuracy, and specificity/sensitivity were examined. These parameters were estimated on the basis of the most intense and characteristic ions in mass spectra of target compounds. Precision and accuracy were less than 5.2 % (RSD) and ±14.0 % (bias), respectively. The LODs were 3 ng/mL for MA and 1.5 ng/mL for AP. At the screening immunoassay had a sensitivity of 100% and a specificity of 95.1 % versus GC-MS for confirmatory testing. The applicability of the method was tested by the analysis of spiked urine and abusers' urine samples.