气相色谱-质谱法分析啤酒中的风味物质

采用乙醚直接萃取和蒸馏-乙醚萃取2种方法提取,以气相色谱一质谱法对啤酒的风味物质进行定性分析,从啤酒中共分离鉴定出37种成分,其主要成分是甲酸异戊酯、甲酸异丙酯、苯乙醇、异戊醇、2-乙氧基丙醇等酯类和醇类物质,它们的含量约占总量的70%以上.     

菠萝挥发性成分的GC-MS分析

采用同时蒸馏萃取法,提取菠萝果实中的香气成分,经气相色谱-质谱联用仪对菠萝挥发性香味化合物进行分离和鉴定,确认其中的44种成分,占总质量分数的90.06%,并用面积归一化法测定各种成分的质量分数,其主要成分为:6-十八烯酸(21.49%),十六酸(16.99%),3一甲硫基丙酸甲酯(5.75%),硬脂酸乙酯(5.44%),硬脂酸(5.00%),辛酸甲酯(3.72%),己酸甲酯(3.19%),5一乙酰基-己酸乙酯(1.53%),糠醛(1.5%)等.     

芒果中香气成分的GC-MS分析

采用同时蒸馏萃取法，提取芒果果实中的香气成分，经气相色谱-质谱联用仪对芒果挥发性香味化合物进行分离和鉴定，确认了其中的68种成分，占总质量分数的96．51％，并用面积归一化法测定了各种成分的质量分数，其主要成分为：异松油烯（44．86％），3-蒈烯（7．06％），棕榈酸（6．04％），亚麻酸（3．44％），4-蒈烯（3．14％），柠檬烯（2．44％），α-水芹烯（2．95％）等。     

DETERMINATION OF ETHYL CARBAMATE IN COMMERCIAL PROTEIN BASED CONDIMENT SAUCES BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Commercially obtained protein based condiments, including soy sauces, were analyzed for the presence of ethyl carbamate (urethane) using combined gas chromatography-mass spectrometry (GC-MS). Samples were spiked with 100 parts-per-billion (ppb) of t -butyl carbamate internal standard, extracted with methylene chloride and concentrated prior to GC-MS analysis. For quantitation, the ratio of the pseudomolecular ions produced during isobutane chemical ionization (CI) at m/z 90 (ethyl carbamate) and m/z 118 ( t -butyl carbamate) were monitored by mass chromatography. Response factors for ethyl carbamate versus the internal standard were determined in both the electron ionization (EI) and chemical ionization modes. The CI mode was used for quantitation as it was more sensitive and interference free. Samples testing positive by CI-MS were subsequently scanned by EI-MS for confirmation of identity as the CI spectra did not contain fragment ions necessary for adequate specificity. This method proved simple and reliable with detection limits less than 1 ppb. Limits of confirmation were 10 ppb. The recovery of internal standard was 86.7%± 5.6%. Only fermented products were found to contain ethyl carbamate.     

GAS CHROMATOGRAPHY AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF SOFT RESINS AND RELATED COMPOUNDS

The α-acids, β-acids, iso-α-acids, hulupones and humulinic acid have been separated by gas chromatography utilising the cool on-column injection technique on various bonded phase capillary columns. The α-acids were separated into cohumulone and humulone; the β-acids into colupulone and lupulone; and the hulupones into cohulupone and hulupone. Iso-α-acids were separated into four peaks; cis-isocohumulone, trans-isocohumulone, cis-isohumulone and trans-isohumulone. Flame ionization detection (FID) and chemical ionization mass spectrometry (CIMS) were used for chromatographic detection. Best results were achieved by employing a DB-1 fused silica capillary column with isooctane as the sample solvent .     

葡萄柚精油的气相色谱-质谱分析

采用水蒸汽蒸馏法提取葡萄柚精油,经气相色谱和质谱联机分析,同时依据各成分的保留指数,鉴定出63种挥发性物质,其中有21种碳氢化合物,32种含氧化合物.在碳氢化合物中以柠檬烯、γ-萜品烯为主要成分;而在含氧化合物中主要是沉香醇、α-萜品醇、百里酚以及一些脂肪族醛.     

密蒙花挥发油成分气相色谱-质谱分析

研究密蒙花中的挥发性化学成分.采用水蒸气蒸馏,用气相色谱-质谱法进行分析,按峰面积归一化法求出挥发性化学成分的相对含量.分离出48个峰,鉴定了30个化合物.结论:已鉴定的化合物包括酮、酸、烷烃、酯、醇、烯烃、联苯及杂环等8类化合物.其中酮类化合物占总色谱流出峰面积的21.52%.酸类占14.83%,烷烃类占12.24%,酯类占10.55%,醇类占10.18%.其主要组分有6,10,14-三基-2-十五烷酮(18.18%),n-十六酸(13.13%),二十八烷(4.25%),邻苯二甲酸丁基2-乙基己基酯(3.74%),3,4-二乙基-1,1-联苯(3.4%),三十五烷(3.39%),(-)-匙叶桉油烯醇(3.25%).     

EXAMINATION OF AN EXTRACT OF CIDER VOLATILES USING BOTH ELECTRON IMPACT AND CHEMICAL IONIZATION GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Gas chromatographic-mass spectrometric examination of the aroma components of a cider made from a single apple cultivar using both electron impact and chemical ionization has led to the identification of 38 compounds not previously reported in ciders. In comparison with electron impact spectra, chemical ionization generally gave a clearer indication of molecular weights and also a relatively simple and more readily interpretable fragmentation. Esters of succinic, malic and lactic acid were amongst the most significant of the components identified, the origin of these and other hydroxy acids are discussed.     

THE ANALYSIS OF NON-VOLATILE CONSTITUENTS OF WINE BY GLASS CAPILLARY GAS CHROMATOGRAPHY*

A considerable amount of quantitative and qualitative information on the non-volatile constituents of wine (acids, sugars, and polyols) can be readily obtained, from small sample volumes without prefractionation, by glass capillary gas chromatography of their trimethylsilyl derivatives. A continuous check on the correct functioning of the method, and in particular on the inertness of the glass capillary and injector, is obtained by the use of two internal standards, whose trimethylsilyl derivatives vary considerably in stability. Any variation in the ratio of the peak areas of the latter derivatives indicates incorrect sample preparation or possible adsorptive/catalytic activity of the GC system. As a general method, the technique may be applied to other alcoholic beverages.     

烃类脉冲裂解产物的气相色谱分析

本文根据并联脉冲微型反应装置的特点,设计了一种带有预切反吹装置的气相色谱体系.用此体系能除去烃类脉冲裂解产物中C_5以上的重质组份,一次性分析氢和C_1—C_4烷烯烃,并能较准确地测量焦碳沉积量.分析迅速,装置简便     

DETERMINATION OF PIRIMIPHOS-METHYL IN PASTA BY GAS CHROMATOGRAPHY/CHEMICAL IONIZATION MASS SPECTROMETRY

A method for the determination of pirimiphos-methyl residues in pasta has been developed. The pesticide was extracted from pasta using the Luke procedure modified for low moisture, nonfatty food products. The extracts were analyzed by capillary column gas chromatography using an ion trap mass spectrometer in the chemical ionization mode as the detector. Quantification was performed using fluorene as the internal standard. The limit of detection was 0.005 ppm. Recoveries from spaghetti were 83.0% at the 0.100 ppm level and 93.3% at the 0.010 ppm level. Of 48 spaghetti samples analyzed, 38 contained detectable residues between trace (>0.005 ppm) and 0.180 ppm. Electron ionization (EI) was used to confirm residues as low as 0.016 ppm in more concentrated extracts.     

气相色谱-质谱联用测定纺织品中10种邻苯二甲酸酯含量的探究

建立了气相色谱-质谱联用法同时测定纺织品中10种邻苯二甲酸酯含量的快速方法。采用适宜的色谱条件对目标产物进行分离,一次进样分离只需23 min。此外,还探究了不同萃取溶剂、萃取方法以及超声萃取溶剂的温度和时间对测定结果的影响。在该方法的色谱条件下,通过测定回收率和目标产物的线性来验证方法的可行性。实验结果表明,6种邻苯二甲酸酯(DIBP、DBP、DPP、BPP、DEHP和DNOP)在0.4~10 mg/L范围内线性良好,加标回收率在85.5%~101.0%范围内,4种邻苯二甲酸酯(DMEP、DIHP、DINP和DIDP)在2~50 mg/L范围内线性良好,加标回收率在92.7%~102.1%范围内,满足ISO 14389-2014的标准要求。     

大枣中微量金属元素的原子吸收光谱法测定

本文采用干法灰化、原子吸收光谱法测定大枣中Fe,Zn,Ca,Mg,K,Pb,Cu,Ni,Cd等9种微量金属元素,回收率达90％～102％,结果令人满意。     

微波消解-原子荧光法同时测定果品中的砷和汞

建立了微波消解-原子荧光法同时测定果品中砷和汞的方法.砷、汞检出限分别为0.1145 μg/L和0.0161μg/L,相关系数达到0.999 8.用该方法进行加标回收实验,砷的回收率为99.48%,汞的回收率为94.75%;测定标准物质砷和汞的含量,均在含量标准值许可范围,相对标准偏差分别为2.59%和4.06%,准确度和精密度高.     

CLASSIFICATION OF CORN ODOR BY STATISTICAL ANALYSIS OF GAS CHROMATOGRAPHIC PATTERNS OF HEADSPACE VOLATILES

At present corn is graded organoleptically into "normal" and various "off-odor" categories. The possibility of classifying corn odor on the basis of gas chromatographic patterns of headspace volatiles was studied using 60 samples of corn and statistical step-wise discriminant and regression analyses. Three options for subdividing the patterns into variables and several transformations for quantitation of peak areas were explored. To obtain optimum odor classification, five to seven gas chromatographic features were necessary. When applied to additional samples, classification at an error probability P < 0.05 (above 95% confidence level) was obtained for some statistical models. Thus, an objective system is feasible for classification of grain odor.