人体气味稳定性的研究

对2位男性个体的手部人体气味分别于同一天、半年后、一年后和15个月后采样,运用SPME-GC/MS法进行分析,通过比较所得样品色谱图和样品中共有成分相对峰面积比的异同并使用相似度分析法对人体手部气味的稳定性进行了研究.结果表明,同一个体的人体手部气味具有稳定性,不同个体的人体手部气味差异明显.     

气-质联用鉴别人体气味

使用顶空固相微萃取结合气相色谱质谱联用法对5位个体的腋窝部人体气味进行了采样分析,通过比较气味样品中共有成分的相对含量的差异和样品中的非共有成分的不同,结合使用相似度软件,对来自于5位个体的腋窝部人体气味样品进行了鉴别,样品得到了有效地区分。     

不同个体足部人体气味的鉴别研究

运用SPME-GC/MS法对5位个体的足部人体气味进行了采样分析,通过比较气味样品中共有成分的相对峰面积比的差异和样品中的非共有成分的不同,并使用斯皮尔曼秩相关法对来自5位个体的足部人体气味样品进行了鉴别,样品均得到了有效地区分。     

应用主成分分析SPME/GC-MS法鉴别人体气味的研究

运用SPME/GC-MS法鉴别来自8位个体的16个腋窝部人体气味样品,得出各样品均含有7种共有成分.以7种共有成分为分析变量,运用主成分分析法对16个样品进行鉴别区分,壬酸、环十二醇和5,9-十一烷酸内酯的含量是决定第1主成分的关键因素,庚醛和己醛的含量是决定第2主成分的关键因素.十八烷和1-茨醇的含量是决定第3主成分的关键因素.     

顶空-气相色谱-质谱指纹图谱应用于烟用香精中主成分测定北大核心CSCD

在平衡温度为80℃,平衡时间为30min下,采用顶空分离进样,气相色谱-质谱法对9个不同批次的烟用香精的成分进行分离和鉴定。根据方法的精密度试验结果,建立了烟用香精的指纹图谱。对上述9个样品所得18个共有峰以及所建立的标准指纹图谱的数据进行比较,并利用相关系数法、夹角余弦法和欧式距离比值法计算不同样品之间的相似度。3种方法计算出的相似度变化趋势一致,均能判断出样品是否合格。     

GC-MS及主成分分析法用于咖啡香精的指纹图谱分析和微差样品的识别

采用正己烷溶剂萃取法提取咖啡香精中的挥发性和半挥发性成分,并通过气相色谱-质谱法建立了咖啡香精的色谱指纹图谱,共定性了22个组分,占总量的87％,采用共有峰率、组分含量的相对标准偏差及相似度等几个指标对6个不同批次的样品进行了评价,结果表明它们之间具有很大的一致性,通过相似度比较和主成分分析的投影显示法区分微差样品。该色谱指纹图谱可用作咖啡香精的质量控制。     

气相色谱-质谱法在人体气味分析中的应用进展

气相色谱-质谱法（GC-MS）是目前分析人体气味的主要技术手段，其不但可以分析人体气味的组成成分，还可以比较不同个体气味之间的差异。该文首先介绍了人体气味的提取和样品前处理的手段，随后对GC-MS在人体气味的采集及储存、成分分析及差异性研究、用于个体识别和健康表征等方面进行了综述，最后对GC-MS在人体气味分析中的发展趋势进行了展望。     

王老吉广东凉茶颗粒的超高效液相色谱指纹图谱研究

建立了适用于王老吉广东凉茶颗粒质量控制的超高效液相色谱指纹图谱分析方法。样品采用甲醇超声萃取30 min,萃取液用超高效液相色谱法进行指纹图谱分析。色谱柱采用Waters ACQUITY HSS T3 C18(3.0mm×150 mm,1.8μm),以0.5%甲酸-乙腈为流动相进行梯度洗脱,流速为0.8 mL/min,柱温35℃。28个共有峰在18 min内得到良好分离,通过对照品对其中4个峰进行了确证。对王老吉广东凉茶颗粒样品进行了相似度分析,23个批次样品的相似度均达到0.95以上;以28个共有峰的相对峰面积进行主成分分析,23批次样品均落在同一区域。相似度评价和主成分分析结果均表明,王老吉广东凉茶颗粒的产品质量稳定性好。该方法快速、高效、稳定,可用于王老吉广东凉茶颗粒的质量控制。     

运用色谱指纹图谱与化学计量学方法对灵芝进行分类

采用95%乙醇为提取溶剂,运用高效液相色谱(HPLC)指纹图谱技术与化学计量学方法,对11个不同灵芝菌株子实体进行分类。通过相似度分析分别获得提取样品指纹图谱的13个共有峰及每个样品之间的相似度;以相对共有峰面积为分析参数,运用化学计量学方法包括聚类分析(HCA)、主成分分析(PCA)及判别分析(DA)对其进行分类,结果分为紫芝、赤芝和美国大灵芝3类。实验结果表明,用化学计量学的方法对灵芝样品的指纹图谱数据进行分析,是一种可用于其分类的科学方法。     

高效液相色谱法分析玉屏风散成分

建立玉屏风散高效液相色谱指纹图谱分析方法,探讨市售饮片对玉屏风散质量一致性的影响。用传统水煎法制备玉屏风散水煎液,采用高效液相色谱法对不同来源的单味药饮片制备的玉屏风散样品进行测定,用色谱指纹图谱相似度评价软件对指纹图谱进行分析,以对照药材制得的标准方剂为参照,评价不同批次饮片对玉屏风散成分的影响。试验结果表明,10批玉屏风散指纹图谱之间的相似度差异较大,与标准方剂的指纹图谱相比较,有6批相似度低于0.5,3批在0.5～0.8之间,1批高于0.9。10批样品指纹图谱中有22个共有峰,利用标准品对照法鉴定了其中6个成分。试验表明药材饮片的来源对玉屏风散的成分影响较大。     

Collection and identification of human remains volatiles by non-contact,dynamic airflow sampling and SPME-GC/MS using various sorbent materials

Human remains detection canines are used in locating deceased humans in diverse scenarios and environments based on odor produced during the decay process of the human body. It has been established that human remains detection canines are capable of locating human remains specifically, as opposed to living humans or animal remains, thus suggesting a difference in odor between the different sources. This work explores the collection and determination of such odors using a dynamic headspace concentration device. The airflow rate and three sorbent materials—Dukal cotton gauze, Johnson & Johnson cotton-blend gauze, and polyester material—used for odor collection were evaluated using standard compounds. It was determined that higher airflow rates and openly woven material, e.g., Dukal cotton gauze, yielded significantly less total volatile compounds due to compound breakthrough through the sorbent material. Collection from polymer- and cellulose-based materials demonstrated that the molecular backbone of the material is a factor in compound collection as well. Volatiles, including cyclic and straight-chain hydrocarbons, organic acids, sulfides, aldehydes, ketones, and alcohols, were collected from a population of 27 deceased bodies from two collection locations. The common compounds between the subjects were compared and the odor profiles were determined. These odor profiles were compared with those of animal remains and living human subjects collected in the same manner. Principal component analysis showed that the odor profiles of the three sample types were distinct.     

Chalcones in bioactive Argentine propolis collected in arid environments

The aim of this study was to assess the chemical and biological profile of propolis samples collected in arid environments of north-western Argentina. The samples were from two phytogeographical regions (Prepuna and Monte de Catamarca Province). Propolis ethanolic extracts (PEE) and chloroform (CHL), hexane (HEX) and aqueous (AQ) sub-extracts of samples from three regions (CAT-I; CAT-II and CAT-III) were obtained. All PEE exhibited antioxidant activity in the DPPH radical scavenging assay (SC50 values between 28 and 43 microg DW/mL). The CHL extract was the most active (SC50 values between 10 and 37 microg DW/mL). The antioxidant activity in the beta-carotene bleaching assays was more effective for PEE and CHL (IC50 values between 2 and 9 microg DW/mL, respectively). A similar pattern was observed for antibacterial activity. The highest inhibitory effect on the growth of human Gram-positive bacteria was observed for CHL-III and CHL-I (Monte region) with minimal inhibitory concentration values (MIC100) of 50 to 100 microg DW/mL. Nine compounds were identified by HPLC-PAD. Two of them (2', 4'- dihydroxychalcone and 2',4'- dihydroxy 3'-methoxychalcone) were found only in propolis samples from the Monte phytogeographical region. We consider that the Argentine arid region is appropriate to place hives in order to obtain propolis of excellent quality because the dominant life forms in that environment are shrubby species that produce resinous exudates with a high content of chalcones, flavones and flavonols.     

Evaluation of malodor for automobile air conditioner evaporator by using laboratory-scale test cooling bench

As one of the measures to improve the environment in an automobile, malodor caused by the automobile air-conditioning system evaporator was evaluated and analyzed using laboratory-scale test cooling bench. The odor was simulated with an evaporator test cooling bench equipped with an airflow controller, air temperature and relative humidity controller. To simulate the same odor characteristics that occur from automobiles, one previously used automobile air conditioner evaporator associated with unpleasant odors was selected. The odor was evaluated by trained panels and collected with aluminum polyester bags. Collected samples were analyzed by thermal desorption into a cryotrap and subsequent gas chromatographic separation, followed by simultaneous olfactometry, flame ionization detector and identified by atomic emission detection and mass spectrometry. Compounds such as alcohols, aldehydes, and organic acids were identified as responsible odor-active compounds. Gas chromatography/flame ionization detection/olfactometry combined sensory method with instrumental analysis was very effective as an odor evaluation method in an automobile air-conditioning system evaporator.     

Combining different analytical approaches to identify odor formation mechanisms in polyethylene and polypropylene

In a previous study, we identified carbonyls as highly odor-active compounds in both unprocessed and processed polypropylene (PP) with higher intensities after processing, indicating a temperature-driven forming mechanism. In the presented work, we studied whether (a) these carbonyls are the major odor drivers to the overall odor of polyolefins, (b) their formation is taking place already at moderate temperatures well below the typical processing temperatures, (c) conventional antioxidants in polyolefins can prevent or reduce their formation, and (d) whether reducing the amount of oxygen present can decrease the overall odor. One polyethylene (PE) and one PP were selected, and both stabilized and unstabilized polymer powder samples were exposed to conditions differing in oxygen concentration and aging time. The changes in the volatile fraction as well as the formation of odor-active compounds were monitored using a multidisciplinary approach by combining analytical methods based on gas chromatography (GC), multivariate data analysis, and sensory methods (GC–olfactometry and a sensory panel). Both investigated materials (PE and PP) showed similar degradation products (aldehydes, ketones, carboxylic acids, alcohols, and lactones) which increased dramatically with increasing aging time and the lack of stabilization. Oxidation products, mainly carbonyl compounds, were responsible for the odor of the investigated materials. The main odor drivers were unsaturated ketones and aldehydes with a chain length between six and nine C-atoms. Interestingly, similar odor patterns were found for both stabilized and unstabilized samples, indicating that similar formation processes take place independent of the stabilization.     

Characterizing Key Volatile Pollutants Emitted from Adhesives by Chemical Compositions,Odor Contributions and Health Risks

As one of the major sources of volatile pollutants in indoor air, gaseous emissions from adhesives during interior decoration have attracted increasing concern. Identifying major volatile pollutants and the risk in adhesive gaseous emissions is of great significance, but remains rarely reported. In the present research, we assessed the major volatile pollutants emitted from white emulsion adhesive and silicone adhesive samples (n = 30) from three aspects: chemical composition, odor and health risk contributions. The results showed that a total of 21 volatile pollutants were detected. Significantly, xylene was the most concentrated compound from white emulsion adhesives, accounting for 45.51% of the total concentrations. Butanone oxime was the most concentrated compound in silicone adhesives, accounting for 69.86% of the total concentrations. The trends in odor concentration (evaluated by the odor activity value method) over time were well correlated with the total chemical concentrations. Xylene (58.00%) and butanone oxime (76.75%) showed the highest odor contribution, respectively. Moreover, from an integrated perspective of chemical emissions, odor and health risk contributions, xylene, ethylbenzene, ethyl acetate and benzene were identified as the key volatile pollutants emitted from the white emulsion adhesives, while butanone oxime, butanone, and ethanol were the key volatile pollutants emitted from the silicone adhesives. This study not only identified the key volatile pollutants but also provided characteristics of odor and health risks of gas emitted from adhesives.     

Comparison on phenolic compounds and antioxidant properties of cabernet sauvignon and merlot wines from four wine grape-growing regions in china

The antioxidant activities in the Cabernet Sauvignon and Merlot wines from four wine grape-growing regions in China were measured by different analytical assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH·), cupric reducing antioxidant capacity (CUPRAC), superoxide radical-scavenging activity (SRSA) and the contents of total phenols, total flavonoids, total flavanols and total anthocyanins were determined. The results showed that the contents of phenolic compounds and the levels of antioxidant activity in the wine samples greatly varied with cultivar and environmental factors of vine growth. The contents of phenolic compounds and antioxidant activities in Cabernet Sauvignon and Merlot wines from the Yuquanying region of Ningxia were significantly higher than other three regions, followed by the wines from Shacheng region of Hebei, and these parameters were the lowest in Cabernet Sauvignon and Merlot wines from the Changli regions of Hebei and Xiangning region of Shanxi. Taken together, a close relationship between phenolic subclasses and antioxidant activity was observed for the wine samples. Moreover, there were significant discrepancies in the individual phenolic composition and content of four regional Cabernet Sauvignon and Merlot wines, among which the individual phenolic compounds (catechin, epicatechin, cinnamic acid, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, laricitrin-3-O-glucoside and isorhamnetin-3-O-glucoside) revealed a significant correlation (p < 0.05) with the antioxidant capacity in present study, especially for catechin and epicatechin.     

A Comparative Evaluation of Nitrogen Compounds in Petroleum Distillates

Although the concentration of nitrogen compounds in crude oil is relatively low, they can become more concentrated in petroleum distillates and poison the catalysts used in refining processes. They cause undesirable deposits, color formation and odor in products; they also contribute to air pollution and some are highly carcinogenic. The poisoned catalyst becomes deactivated for hydrodesulfurization and unable to remove sulfur from middle distillates. In order to understand the effect on catalytic processes, it is desirable to identify the nitrogen compounds in various petroleum distillates. This paper compares the nitrogen species profiles in different petroleum distillates using a nitrogen chemiluminescence detector. In addition, four different petroleum distillate samples from different refineries were analyzed to find the variation in their nitrogen profiles. The nitrogen compounds in petroleum distillate samples were identified as anilines, quinolines, indoles, and carbazoles and their alkyl derivatives. Quantitation was carried out against known reference standards. The quantitative data were compared to the total nitrogen content determined by elemental analysis.