• Mass Spectrometry Letters
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• v.4 no.4
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• pp.75-78
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• 2013

A gas chromatography/mass spectrometric (GC/MS) method was developed as a candidate reference method for the accurate determination of essential fatty acids (linoleic acid, ${\alpha}$- and ${\gamma}$-linolenic acids) in food supplemental oil products. Samples were spiked with three internal standards (stearic acid-$d_{35}$, $^{13}C_{18}$-linoleic acid, and $^{13}C_{18}$-${\alpha}$-linolenic acid). Samples were then subject to saponification, derivatization for methylation, and extraction by organic solvent. For GC/MS measurement, an Agilent HP-88 column, designed for the separation of fatty acid methyl esters, was selected after comparing with other columns as it provided better separation for target analytes. Target analytes and internal standards were detected by selected ion monitoring of molecular ions of their methyl ester forms. The GC/MS method was applied for the measurement of three botanical oils in NIST SRM 3274 (borage oil, evening primrose oil, and flax oil), and measurement results agreed with the certified values. Measurement results for target analytes which have corresponding isotope-labeled analogues as internal standard were calculated based on isotope dilution mass spectrometry (IDMS) approach, and compared with results calculated by using the other two internal standards. Results from the IDMS approach and the typical internal standard approach were in good agreement within their measurement uncertainties. It proves that the developed GC/MS method can provide similar metrological quality with IDMS methods for the measurement of fatty acids in natural oil samples if a proper fatty acid is used as an internal standard.

• Analytical Science and Technology
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• v.17 no.4
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• pp.322-336
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• 2004

The improved derivatization technique of tamoxifen metabolite in human urine is described for the acylation method that they are substituted by derivatization reagent like acyl anhydride for use of gas chromatography/mass spectrometry. The hydroxyl group of tamoxifen metabolite was derivatized by trifluoroacetic anhydride (TFAA), pentafluoroacetic anhydride (PFPA) and heptaflorobutylic anhydride (HFBA). It was investigated to the gas chromatography/mass spectrometry (GC/MS) technique use negative ion chemical ionization (NCI), positive ion chemical ionization (PCI) and electron impact (EI). In acylation of the metabolites of tamoxifen, the effective reaction temperature and time were shown to be at $50^{\circ}C$ for 30 min. The 4-hydroxytamoxifen, which is known to major metabolite of tamoxifen, was not detected in human urine, whileas the hydroxymethoxytamoxifen was detected. We thought that this result was from the single dose of tamoxifen.

• Journal of Nutrition and Health
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• v.18 no.4
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• pp.293-300
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• 1985

Volatile components of Korean horseradish roots harvested at different dates were prepared by steam distillation. Samples were examined by gas chromatography (GC) and combined gas chromatography-mass spectrometry (GC-MS). The major pungent constituent, allyl isothiocyanate was confirmed add tended to increase with delayed harvest time. Pungent principles also included allyl thiocyanate, 2-phenethyl, 2-butyl, 4- pentenyl, benzyl and 3-methylthiopropyl isothiocyanates. Infrared (IR) spectroscopy study showed that allyl isothiocyanate - thiocyanate interconversion did not occur under the condition of this study.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.106-114
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• 1963

The products from polymer pyrolysis at $450^{\circ}$ are cooled with ice, then liquid and gaseous portions are analysed by gas chromatography. Di-2-ethyl hexyl sebacate column, silicone oil column, silica gel column and tetraethyleneglycol dimethylether column, which was most effective for the separation of hydrocarbon gases, are used. Identification of isomers could be secured more effectively by gas chromatography than mass spectrometry. Elucidation of the mechanism for thermal decomposition of polymers could be done through the identification of pyrolysis products. Although more extensive work is needed, some patterns of polymer pyrolysis are discussed.

• Mass Spectrometry Letters
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• v.3 no.3
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• pp.74-77
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• 2012

Organic acid (OA) profiling analysis was performed in culture media from Lactobacillus pentosus K34 (L. pentosus K34) and Pediococcus lolli PL24 (P. lolli PL24) by gas chromatography-mass spectrometry (GC-MS) following methoxime/tert-butyldimethylsilyl derivatives. 12 OAs were positively identified in culture media. Most of OA levels from L. pentosus K34 of hetero lactic fermentation were found to be higher when compared with those from P. lolli PL24 of homo lactic fermentation, which may explain different OA metabolism in each strain. In addition, the distorted dodecagonal star patterns were readily distinguishable, and the characteristics of each strain were well represented. The present study demonstrates that the OA metabolic profiling method by GC-MS combined with star pattern recognition is useful for the monitoring study of characteristic OA metabolism in various microorganisms.

• Food Science of Animal Resources
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• v.21 no.3
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• pp.256-264
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• 2001

Pyrolysis/GC-mass spectrometry(Hewlet-Packard 5890GC/mass selective detector, 5971 BMSD), interfaced to a CDS Pyroprobe 1500 was optimized for rapid analysis of flavour compounds in Cheddar cheese. Twenty flavour compounds, including aldehydes(4), ketones(4), fatty acids(10), alcohol(1), and hydrocarbon(1), were identified from Cheddar cheeses. In total, Twenty-three flavour compounds aldehydes(2), ketones(8), alcohols(3), fatty acids(7), lactone(1), benzene derivative(1) and amide(1) were identified from two samples of accelerated-ripened Cheddar cheese treated with the proteolytic enzymes of Lactobacillus casei LGY. In total, Twenty-one flavour compounds; aldehydes(2), ketones(5), alcohols(2), fatty acids(11), and lactone(1) were identified from enzyme-modified cheese(EMC) treated with the combination of the proteolytic enzymes of Lactobacillus casei LGY and commercial endopeptidase or lipase. However, All the flavour compounds identified by pyrolysis/GC/MS in samples of ARC and EMC were not determined whether they are recognized as typical Cheddar flavour or not. More studies were requested on the development of methods for a rapid and convienent analysis of dairy fermented products using pyrolysis/GC-mass spectrometry.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.575-578
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• 2005

Electrospray ionization mass spectrometry (ESI MS) was used, along with gas chromatography-mass spectrometry (GC-MS), to monitor Paal-Knorr synthesis of 2,5-dimethyl-1-phenylpyrrole by condensation of aniline with 2,5-hexanedione. In addition to 2,5-dimethyl-1-phenylpyrrole observed as a single spot by TLC, unexpected dimer size compounds were observed by GC-MS. Dimers and trimers were observed by ESI MS. ESI tandem mass spectrometry was used to select plausible structures for the dimer. ESI MS with or without liquid chromatographic separation is useful for observing oligomeric byproducts with low volatility produced in organic reactions.

• Journal of Environmental Science International
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• v.11 no.4
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• pp.375-382
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• 2002

The total hydrocarbon distribution of oil products obtained from the pyrolysis of four kinds of mixtures of polyethylene-polystyrene waste has been studied by multidimensional chromatography(high performance liquid chromatography followed by capillary gas chromatography)/mass spectrometry. Saturated, unsaturated and aromatic hydrocarbons in oil products were selectively pre-separated according to structural groups by HPLC and the weight fraction of each group was estimated by analysis of each component using GC-FID response factors. The hydrocarbon distribution of aliphatic fraction consists of $C_{5}$ to $C_{25}$ saturated and unsaturated hydrocarbons. And that of aromatics fraction consists of benzene, toluene, xylene, styrene, propenyl benzene, naphthalene, and some of derivatives. Pyrolysis temperature did not affect the ratio of total weight fraction of aliphatic over aromatic hydrocarbon distribution in case of PS only and PE-PS mixtures (1:1 and 1:4 wt. ratio) as a feed while affected the ratio of total wt. fraction in case of PE only. The optimal temperature for the maximum oil production was $600^{\circ}C$ for pyrolysis of PS and 1:1 and 1:4 mixtures of PE and PS. The optimal condition for aromatic recovery was $600^{\circ}C$ with 1:1 mixture of PE and PS. In this condition, aromatic was produced up to 90% of total oil product. The maximum yield of toluene, xylene, styrene, and propenyl benzene were 8.6, 8.9, 51.0 and 7.4% of feed for pyrolysis PS at $700^{\circ}C$, respectively. However, only 1.3% naphthalene was recovered at $700^{\circ}C$ with 1:1 PE:PS(by wt.).

• Mass Spectrometry Letters
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• v.4 no.1
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• pp.18-20
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• 2013

Headspace solid phase micro-extraction gas chromatography/flame ionization detection (HS-SPME-GC/FID) method was compared with headspace gas chromatography/mass selective detection (HS-GC/MS). Organic solvent-spiked urine as well as urine samples from workspace was analyzed under optimal condition of each method. Detection limit of each compound by HS-SPME-GC/FID was $3.4-9.5{\mu}g/L$, which enabled trace analysis of organic solvents in urine. Linear range of each organic solvent was $10-400{\mu}g/L$, with fair correlation coefficient between 0.992 and 0.999. The detection sensitivity was 4 times better than HS-GC/MS in selected ion monitoring (SIM) mode. Accuracy and precision was confirmed using commercial reference material, with accuracy around 90% and precision less than 4.6% of coefficient of variance. Among 48 urine samples from workplace, toluene was detected from 45 samples in the range of $20-324{\mu}g/L$, but no other solvents were found. As a method for trace analysis, SPME HS GC/FID showed high sensitivity for biological monitoring of organic solvent in urine.

• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.52-56
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• 1993

Flavor compounds formed in the ramyon fried in palm oil at $148-150^{\circ}C$ for 1 minute during storage at $65^{\circ}C$ were isolated and identified by gas chromatography-mass spectrometry. Their changes in the amount when the ramyon was stored at 20, 40 and $65^{\circ}C$ were also studied by using static headspace gas chromatography. Pentane, hexane, butanal, heptane, 1-pentanol, hexanal, and octane were formed during $65^{\circ}C$ storage of the ramyon and they were thought to be from linoleic and oleic acid present in ramyon. Formation of the flavor compounds was shown to increase with the storage temperature and/or storage time. Hexanal showed the highest correlation with the sensory score(r=0.87).