Publications (2)1.44 Total impact
Article: Differentiation of bacteria using fatty acid profiles from gas chromatography-tandem mass spectrometry.[show abstract] [hide abstract]
ABSTRACT: Fatty acids are essential components in cell membranes of bacteria, and they determine the different structures of lipids and lipid A. Therefore, fatty acids are good targets for development of rapid and reliable methods for differentiation of bacteria. Here we report fatty acid distributions in three different bacteria-Escherichia coli, Francisella novicida and Bacillus subtilis-studied by using gas chromatography-tandem mass spectrometry. Different fatty acid profiles were observed in the three bacteria. Hydroxyl fatty acids were observed in E. coli and F. novicida, but not in B. subtilis. Carbocyclic fatty acids were observed in E. coli but not in F. novicida or B. subtilis. Methyl-branched fatty acids were observed in B. subtilis but not in E. coli or F. novicida. Although saturated and unsaturated fatty acids were all observed in the three bacteria, their chain lengths and distribution patterns were different. The results indicate that the fatty acid profile in a given bacterium is highly specific, and gas chromatography-tandem mass spectrometry is a rapid and sensitive method for the identification or detection of bacteria.Journal of the Science of Food and Agriculture 06/2010; 90(8):1380-3. · 1.44 Impact Factor
Article: [Rapid determination of volatile flavor compounds in soy sauce using head space solid-phase microextraction and gas chromatography-mass spectrometry].[show abstract] [hide abstract]
ABSTRACT: A rapid and simple method was developed for the determination of volatile flavor compounds (VFCs) in soy sauce by head space solid-phase microextraction (HS-SPME) coupled to capillary gas chromatography-mass spectrometry (GC-MS). Five types of SPME fibers, including 85 microm PA, 100 microm PDMS, 75 microm CAR/PDMS, 65 microm PDMS/DVB, 50 microm DVB/CAR/PDMS were investigated. Three parameters for HS-SPME in terms of adsorption time, salt concentration, and extraction temperature were optimized. Adsorption time tested in this study were 20, 40 and 60 minutes; the salt concentrations were 180, 210, 250, 270 and 300 g/L; and extraction temperatures were 25, 35, 45, 55 and 65 degrees C. The concentrations of the compounds were calculated based on their relative peak areas to the internal standard of 2-octanol. An 85 microm PA fiber, adsorption time of 40 min, a temperature of 45 degrees C and NaCl concentration of 250 g/L were selected as th optimum conditions. This optimized method was applied to evaluate a real sample. As a result, 97 compounds in a soy sauce sample were isolated and identified successfully. The results showed that alcohols, carboxylic acids, esters and phenols were the major VFCs of soy sauce. The most important groups of volatile compounds in the soy sauce sample were ethanol, hexadecanoic acid, phenylethyl alcohol and 2,3-butanediol. In addition, some oxo-compounds and heterocyclic compounds were also found. The average relative standard deviation of the relative peak area was 12.1%, and the recoveries were 79.9% - 109.6%. The method is simple, fast and accurate with high reproducibility, high sensitivity and low cost.Se pu = Chinese journal of chromatography / Zhongguo hua xue hui 06/2008; 26(3):285-91.