• Preventive Nutrition and Food Science
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• 제4권2호
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• pp.88-91
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• 1999

Aroma components of tea processed from Korean chicory roots were isolated and identified. The model system of amino-carbonyl reaction was carried out to study the formation mechanism of aroma compounds of chicory tea during manufacturing process. The concentration extracts from chicory tea and model system were analyzed and identified by gas chromatography(GC) and GC-mass spectrometry. Twenty-nine compounds, including pyrazines, furans, acids, alcohols, pyrroles and lactones were isolated and identified in chicory tea. The main compounds were pyrazines including methyl pyrazine, 2,5-dimethyl pyrazine, 2, 6-dimethyl pyrazine, 2-ethyl-6-methyl pyrazine, 2-ethyl-3-methyl pyrazine, thrimethyl pyrazine, 3-ethyl-2-5-dimenthyl pyrazine, 5-ethyl-2-3-dimenthyl pyrazine, and 2-acetyl-3-methy pyrazine and pyrroles including acethl pyrrole and formlyl pyrrole ; and furans including furfural , acetyl furan, 5-methyl furan, 5-methyl furfuralm, and furfuryl alcohol. These pyrazine compounds of a roasted and nutty aroma may be important contributors to the flavor of chicory tea. The aroma concentrate of model system also had a roasted and nutty aroma and the main compounds were methyl pyrazine, 2, 5-dimetyl pyrazine, 2, 6-dimethyl pyrazine and trimethyl pyrazine.

• 약학회지
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• 제51권3호
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• pp.206-213
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• 2007

Recently estimating the uncertainty of an analytical result has become an essential part of quantitative analysis. This study describes the uncertainty of the measurement for the determination of methamphetamine and its major metabolite amphetamine in human hair, The method consists of washing, drying, weighing, incubation and extraction with methanolic HCI solution, clean-up, trifluoroacetyl derivatization, and qualification/quantification of residues by gas chromatography/mass spectrometry (GC/MS). Traceability of measurement was established through traceable standards and calibrated volumetric equipment and measuring instruments. Measurement uncertainty associated with each analyte in real samples was estimated using quality control (QC) data. The main source of combined standard uncertainty comprised two components, which are uncertainties associated with calibration linearity and variations in QC, while those associated with preparation of analytical standards and sample weighing were not so important considering the degree of contribution. Relative combined standard uncertainties associated with the described method ranged for individual analytes from 4.99 to5.03%.

• Bulletin of the Korean Chemical Society
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• 제24권9호
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• pp.1276-1280
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• 2003

Thermal behavior of bromphenols was investigated by direct pyrolysis at high temperature. The thermal degradation products formed by the pyrolysis of mono-bromophenols (o-, m-, and p-) were identified by gas chromatography-mass spectrometry. During the pyrolysis reactions, several kinds of dioxins and furans were produced, and the relative ratio of pyro-products was dependent on the substituted position of bromine in phenolic structure due to the effect of symmetry and steric hindrance. The formation of dioxins can be explained by the phenoxy radical addition and Br atom elimination at an ortho-carbon site on phenolic structure. On the other hand, the formation of furans can be explained by the ortho-ortho carbon coupling of phenoxy radicals at unsubstituted sites to form o, o'-dihydroxydiphenyl intermediate via its keto-tautomer, followed by $H_2O$ elimination. The pyrolysis temperature has also a substantial effect on the dimerized products quantities but little effect on the type of pyro-products. Moreover, the formation mechanism of pyro-products was suggested on the basis of products identified.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.809-814
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• 2011

A method based on the TMS derivatives and acidic hydrolysis was developed for the simultaneous determination of free and conjugated steroidal hormones in surface water. A silylation of five natural and two synthetic steroidal hormones was achieved with N-methyl-N-(trimethylsilyl) trifluoroacetamide/$NH_4I$ (1000:3) under catalysis of dithioerythritol for 60 min at $80^{\circ}C$. TMS derivatives of the steroid hormones containing multifunctional groups offer a single derivative product under this condition. The accuracy of the analytes was in the range of 87 to 110% at a concentration of 20 and 50 ng/L with relative standard deviations of less than 10%. The method detection limit was in the range of 0.01 to 0.02 ng/L for surface water. Natural steroidal hormones were detected in a concentration range of 0 to 1.03 ng/L in free form and 0 to 14.6 ng/L in conjugated form, respectively. We found that most of the natural hormonal steroids exist in conjugate forms (43 to 100%) in river water.

• 한국식품영양과학회지
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• 제28권2호
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• pp.305-311
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• 1999

The volatile compounds of soybean pastes(home made soondoenjang, commercial doenjang) were classified into basic, acidic and neutral fractions by dynamic headspace method. The fractionated flavor isolates were analyzed and identified by gas chromatography mass spectrometry. Each peak area of the flavor components was quantified at its ratio to the peak area of internal standard. Sixty one compounds from home made soondoenjang, and forty three compounds from commercial doenjang were identified. The different distribution of volatile compounds between the two soybean paste samples was observed. Ten pyrazines and benzothiazole were identified in the basic fraction of home made soondoenjang. On the other hand, trimethylpyrazine was the only one of nitrogen containing compounds in the commercial doenjang, which was made from soybean(28.3%), wheat(22.2%) and alcohols. The factors which influenced the levels of these identified compounds were considered to be the starting materials of soybean paste. Alcohols, esters and aldehydes in the neutral fraction of both samples were seemed to be characterisitic soybean paste flavor and showed much higher quantities than those of the basic or acidic fractions. Furfural in the commercial doenjang was the highest content (45.28ppm) among all of the compounds identified in the samples.

• 한국식품영양과학회지
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• 제28권2호
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• pp.312-318
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• 1999

Volatile compounds in salt fermented anchovy on the market were analyzed by vacuum simulta neous distillation solvent extraction/gas chromatography/mass spectrometry/olfactometry(V SDE/ GC/MS/O) and aroma extract dilution anlaysis(AEDA). Predominant odorants(Log3FD$\geq$8) in sample were ethyl methylbutanoate(candy like/sweet) and 2 ethyl 3,5 dimethylpyrazine(nutty/baked potato like). Besides these compounds, 6 odorants such as ethyl 3 methylbutanoate(sweet/floral/ candy like), 3 methylbutanal(dark chocolate like), (Z) 4 heptenal(rancid/fish like), (methylthio) propanal(soy sauce /baked potato like), (E,Z) 2,6 nonadienal(melon /cucumber like) and (E,E) 2,4 decadienal(fatty/cooked soybean like) were potent in odor value of salt fermented anchovy. Seven amino acids having high taste value in sample were glutamic acid, aspartic acid(sour and umami taste), lysine, alanine(sweet), histidine, valine, and methionine(bitter).

• 한국식품영양과학회지
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• 제28권2호
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• pp.319-325
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• 1999

Volatile flavor compounds in Korean salt fermented shrimp on the market were analyzed by vacuum simultaneous distillation solvent extraction/gas chromatography/mass spectrometry/olfac tometry(V SDE/GC/MS/O) and aroma extract dilution anlaysis(AEDA). A total of 32 volatile com pounds were detected by GC/O analysis. Of these, 18 were positively identified, and composed of S containing compounds(5), aldehydes(4), ketones(3), N containing compounds(3), ester(1), alcohol(1) and aromatic hydrocarbon(1). Predominant odorants(Log3FD$\geq$4) in salt fermented shrimp were 2,3 butanedione(sour/buttery), 1 octen 3 one(earthy/mushroom like), dimethyl trisulfide(cooked cabbage /soy sauce like) and 2 acetylthiazole(grainy/nutty). Predominant free amino acids were aspartic acid, glutamic acid(sour and umami taste), arginine, methionine(bitter) and lysine(sweet and bitter) in evaluation of taste value.

• Preventive Nutrition and Food Science
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• 제11권3호
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• pp.232-236
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• 2006

The essential oil of Swertia chirata Buch.-Ham. was extracted by solvent extraction (n-pentane:diethylether, 1:1) method using simultaneous distillation-extraction (SDE) apparatus and analyzed by gas chromatography-mass spectrometry (GC/MS). The yield of essential oil obtained from S. chirata was 236.47 mg/kg. Seventy seven compounds of the essential oil belonging to chemical classes of acid (4), alcohol (21), aldehyde (15), ester (3), furan (3), hydrocarbon (7), ketone (17) and miscellaneous (7) were tentatively identified. The major volatile compounds ranged in content order were as follows: undecanoic acid (28.63%), 2-buten-2-one (20.42%), camphor (18.40%), 2-heptadecanone (14.72%), and cedrol (13.07%).

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3603-3609
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• 2011

A novel sampling method of the headspace poly(dimethylsiloxane) (PDMS) mini-disk extraction (HS-PDE) was developed, optimized, validated and applied for the GC/MS analysis of spices flavors. A prototype PDMS mini-disk (8 mm outer diameter, 0.157 mm thickness, 9.4 mg weight) has been designed and fabricated as a sorption device. The technique uses a small PDMS mini-disk and very small volume of organic solvent and less sample size than the solvent extraction. This new HS-PDE method is very simple to use, inexpensive, rapid, requires less labor. Linearities of calibration curves for ${\alpha}$-pinene, ${\beta}$-pinene, limonene and ${\gamma}$-terpinene by HS-PDE combined with GC/MS were excellent having $r^2$ values greater than 0.99 at the dynamic range of 6.06~3500 ng/mL. The limit of detection (LOD) and the limit of quantitation (LOQ) showed very low values. This method exhibited good precision and accuracy. The overall extraction efficiency of this method was evaluated by using partition coefficients ($K_p$) and concentration factors (CF) for several characteristic components from nutmeg and mace. Partition coefficients were in the range from $2.04{\times}10^4$ to $4.42{\times}10^5$, while CF values were 0.88-15.03. HS-PDE was applied successfully for the analysis of flavors compositions from nutmeg, mace and cumin. The HS-PDE method is a very promising sampling technique for the characterization of volatile flavors.

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.3963-3970
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• 2012

Headspace (HS) and headspace solid-phase microextraction (HS-SPME) were studied for extracting volatile organic compounds (VOCs) from whole blood, with chemical and instrumental variables being optimized for maximum sensitivity: incubation at $60^{\circ}C$, equilibration for 30 min, pH 11, and 2 mL injection volume. Both techniques provided accurate analyses, with detection limits of 0.05-0.1 ng $mL^{-1}$ and 0.05-0.5 ng $mL^{-1}$. HS showed better sensitivity, reproducibility, and analysis times than HS-SPME. Overall levels of chloroform in whole blood were found to be 0.05-5.84 ng $mL^{-1}$; detected levels of benzene were 0.05-2.20 ng $mL^{-1}$.