顶空固相微萃取-气相色谱/质谱联用法研究枸桔中的香气化合物

采用顶空固相微萃取-气相色谱/质谱联用法分析了湖北江汉平原的枸桔中香气化合物以及其随枸桔成熟度的变化,以D-柠檬烯、α-蒎烯、芳樟醇、α-松油醇为代表,获得了顶空固相微萃取的最佳萃取条件。气相色谱-质谱(GC-MS)联用技术结果表明:从枸桔果肉中共检测出60种香气成分,其中烃类32种,酯类10种,醇类7种,醛类11种;从果皮中共检测出37种香气成分,其中烃类27种,酯类1种,醇类3种,醛类5种,其它类1种。生长初期、中期和成熟期的枸桔果肉共有的香气成分有14种,果皮共有的香气成分有13种,其中生长初期枸桔果实中的总香气含量最高。     

气相色谱-质谱联用法分析北大仓白酒香气成分

利用溶剂萃取法进行分离和富集,采用气相色谱-质谱联用技术对北大仓白酒香气成分进行分析。从北大仓白酒的二氯甲烷萃取物中分离并鉴定了30种物质,其中酯类22种,占所有香气物质的94.847%;酸类2种,占4.659%;烷烃类2种,占0.228%;醇类2种,占0.185%;酮类1种,占0.060%;酸酐类1种,占0.021%。所含主要化合物为己酸乙酯、2-羟基丙酸乙酯和己酸,合计占总香气成分的96.396%,构成了北大仓白酒香气成分的骨架。     

氧化物与稀土磷酸盐复合陶瓷的切削加工性评价

应用模糊综合评判原理, 评价可加工陶瓷材料的切削加工性, 判断材料的切削加工性等级.通过Ce-ZrO2/CePO4复合陶瓷的材料制备、性能测试、模糊综合评判和加工实验, 研究了氧化物与稀土磷酸盐复合陶瓷的材料切削加工性.根据模糊数学提出一种可加工陶瓷材料切削加工性的综合评判方法.以陶瓷材料的力学性能参数为因素集, 选择5种切削加工性等级, 根据隶属函数计算模糊矩阵, 通过模糊变换确定出氧化物与稀土磷酸盐复合陶瓷的切削加工性.综合评判结果将所制备的几种Ce-ZrO2/CePO4复合陶瓷材料分为3个切削加工性等级, 材料的切削加工性等级随CePO4含量的增加而提高, 评判结果与钻削实验的材料去除率结果相符.Ce-ZrO2/CePO4复合陶瓷材料的钻削加工表面具有明显的塑性变形加工痕迹.还分析了含LaPO4的其它氧化物复合陶瓷材料的切削加工性等级.材料切削加工性的评价方法建立了材料性能与加工技术之间的关系, 可提供一种新的材料设计方法.     

GC-O-MS法对酒花中香气活性成分的分析

采用顶空固相微萃取气相色谱-嗅闻-质谱((HS-SPME-GC-O-MS)联用的方法研究酒花中的香气化合物的组成和风味,并与传统的同时蒸馏萃取、水蒸气蒸馏方法进行比较,定性采用质谱谱库检索结合保留指数进行验证。结果表明:3种方法测得的1号酒花中的香气活性成分存在较大的差异,HS-SPME法最为适合,该法共鉴定出71种成分,占总峰面积质量分数的97.93%,以月桂烯、β-石竹烯为主要成分的萜烯类化合物共22种,其质量分数达88.73%,醇类及酯类质量分数分别为1.98%,3.42%。采用该方法对3个不同的酒花品种定性并嗅闻,能够嗅闻到的香气活性成分共计34种,包括碳氢化合物(包括萜烯)类7种,醇(酚)类11种,酯类10种,酮类2种,未知化合物4种。嗅闻结果表明,在1号、2号、3号3种酒花中分别嗅闻到了26,23,16种香气物质,其中重要的香气活性成分为β-香茅醇、β-石竹烯、里那醇、香叶醇、α-萜品醇、β-香茅醇、橙花醇、橙花椒醇、香叶酸甲酯、辛酸甲酯、乙酸香叶酯等。     

固相微萃取结合气-质联用分析麻椒挥发性成分

以四川广元产的麻椒为原料,利用固相微萃取技术对麻椒中的挥发性成分进行提取,分别用装有HP-5ms和HP-INNOWAXms两种色谱柱的GC-MS进行分离与鉴定;采用质谱与保留指数进行定性,共鉴定出99种成分,其中烯烃类58种、醛类15种、醇类9种、酯类7种、酮类3种、其他烃类4种、其他化合物3种。采用面积归一化法确定了它们相对含量,含量较高的有芳樟醇、D-柠檬烯、β-崖柏烯、β-水芹烯、β-月桂烯、β-蒎烯、(-)-右旋吉玛烯、石竹烯、γ-萜品烯、3-崖柏烯、(Z)-β-罗勒烯、(1R)-(+)-α-蒎烯、(+)-3-蒈烯、(Z,Z,Z)-1,5,9,9四甲基-1,4,7环-十一碳三烯、萜品油烯。从鉴定出的挥发性成分的香气特征可知,烯烃类、醇类和醛类对麻椒的香气贡献较大。     

气相色谱-质谱对天然酿造酱油与配制酱油香气成分的分析比较

利用蒸馏萃取/气相色谱-质谱(SDE/GC-MS)方法对酱油香气成分进行了分析,在4种不同工艺生产的酱油中共鉴定出51种化学成分,其中醇类12种、酚类5种、醛酮8种、酸类6种、酯类7种、杂环化合物类13种,同时发现,3种酿造酱油中的共有成分为35种.不同工艺生产的酿造酱油中醇、酚、醛酮、酯类物质的种类均比配制酱油多1倍以上,酸类物质的总含量也远大于配制酱油,但配制酱油的杂环类风味物质比较丰富,主要为体现烤香风味的吡嗪类化合物.乙醇、2-甲基丙醇、3-己醇、3-甲硫基丙醇、苯乙醇、乙烯基-2-甲氧基-苯酚、4-乙基-苯酚、α-亚乙基-苯乙醛、香草醛、2-羟基丙酸乙酯、乙酸乙酯、乙酸苯甲酯、亚油酸乙酯、5-甲基糠醇、3-苯基呋喃为酿造酱油的特有成分.构成酱油特征香气成分的4-乙基愈创木酚、糠醇、糠醛等物质的含量在配制酱油中也相对较少.这正是酿造酱油与配制酱油风味不同的原因之一.该文研究结果验证了生产酿造酱油时不同原料不同工艺会对风味物质产生影响.     

固相微萃取-气相色谱-质谱测定杨梅香气

对利用固相微萃取-气相色谱-质谱联用仪分析杨梅果汁香气成分过程中的萃取及色谱质谱条件等关键因素进行了研究.通过优化条件,确定最佳萃取条件为:8 mL果汁加入1 g NaCl,50/30 μm的DVB/CAR/PDMS纤维头在50 ℃下萃取30 min.气质分析时,采用小直径衬管,并控制合适的质谱条件,可提高痕量组分响应及匹配度.通过面积归一法,确定杨梅香气主要成分为:4种烯类物质,约占62.59%;8种醇类物质,约12.68%;2种酯类,约0.89%.     

色谱指纹图谱在苹果酒质量评价中的应用

采用反相高效液相色谱-电化学检测法研究了14种苹果酒样品的指纹图谱。以标准品绿原酸进行定位,通过对图谱分析和相对保留时间计算,确定了8个共有峰。根据共有峰的峰面积用相关系数法和向量夹角余弦法计算相似度,两种方法的计算结果一致。实验结果表明同一厂家生产的苹果酒相似度较好。该法为苹果酒的产品分析提供了有效的微观信息,为苹果酒的质量控制、新产品的研发以及苹果酒行业标准的制定提供一种可行思路。     

模糊综合评判法在台州市地表水评价中的应用

应用模糊综合评判法,以长潭等9个水库为研究对象,对台州地区水质进行厂评价：结果表明,台州地区总体水质较好,除东湖属Ⅳ类水外,其它全为Ⅲ类,适合人们生存及生产需要。根据评价提出了相心的建议     

应用顶空气相-离子迁移谱与相对气味活度值法分析卷烟特征香气物质

为考察不同卷烟产品挥发性物质的差异,剖析不同卷烟产品香气风格特征,选取5款不同品牌市售 卷烟,基于顶空气相－离子迁移谱（HS－GC－IMS）开展卷烟挥发性物质研究,采用相对气味活度值法 （ROAV）分析不同卷烟特征香气物质。HS－GC－IMS结果表明,5款卷烟产品的挥发性有机物组分大致相同, 但不同化合物的含量之间存在较大差异;ROAV分析结果表明,主要挥发性物质为醛类、酮类、醇类和酯类, 对卷烟香气有重要贡献的物质包括糠硫醇、1-辛烯-3-酮、呋喃醇、3-甲基丁醛、乙酸异戊酯等,化合物间含 量和感觉阈值的差异影响了其对卷烟香气风格的贡献度,进而影响卷烟的风格特征。借助 HS－GC－IMS和 ROAV值可以剖析不同卷烟特征香气物质,为卷烟产品的风格分析和品质评定提供一定技术支持。     

Chemometric characterisation of Basque and French ciders according to their polyphenolic profiles

Polyphenolic compositions of Basque and French ciders were determined by HPLC-DAD following thiolysis, in order to characterise and differentiate these beverages and then develop a classification system capable of confirming the authenticities of both kinds of cider. A data set consisting of 165 cider samples and 27 measured features was evaluated using multivariate chemometric techniques, such as cluster analysis and principal component analysis, in order to perform a preliminary study of data structure. Supervised pattern recognition techniques such as linear discriminant analysis (LDA), K-nearest neighbours (KNN), soft independent modelling of class analogy (SIMCA), and multilayer feed-forward artificial neural networks (MLF-ANN) attained classification rules for the two categories using the chemical data, which produced satisfactory results. Authentication systems obtained by combining two of these techniques were proposed. We found that SIMCA and LDA or KNN models achieved 100% hit-rates, since LDA and KNN permit the detection of every Basque cider and SIMCA provides a model for Basque cider that excludes all French ciders. Polyphenolic profiles of the ciders provided enough information to be able to develop classification rules for identifying ciders according to their geographical origin (Basque or French regions). Chemical and organoleptic differences between these two types of cider are probably due to the original and distinctive cidermaking technologies used for their elaboration. Using polyphenic profiles, about 80% of French ciders could be distinguished according to their region of origin (Brittany or Normandy). Although their polyphenolic profiles did not provide enough information to achieve an authentication system for Breton and Norman ciders.Abbreviations AVI Avicularin - CQA Caffeoylquinic acid - CAF Caffeic acid - CAT (+)-catechin - CT-1, -2, -3 Unknown flavan-3-ols - DPn Average degree of polymerization of procyanidins - EC (–)-epicatechin - HCA-7 Ferulic acid - HCA-1, -2 ,-3, 4, -5, -6 Unknown hydroxycinnamic acids - HYP Hyperin - IQC Isoquercitrin - PC Total procyanidins - PCM p-Coumaric acid - PCQ p-Coumaroylquinic acid - PL Phloretin - PLG Phloridzin - PLXG phloretin-2-O-xyloglucoside - PPO Polyphenoloxidase - QCE Quercetin - QCI Quercitrin - RUT Rutin - CA Cluster analysis - KNN K-nearest neighbours - LDA Linear discriminant analysis - MLF-ANN Multilayer feed-forward-artificial neural network - PCA Principal component analysis - PC1 First principal component - PC2 Second principal component - PC3 Third principal component - RMSE Root medium square error - SD Standard deviation - SIMCA Soft independent modelling of class analogy - DAD Diode array detector - HPLC High Performance Liquid Chromatography - ND Not detected     

Elemental Characterization of Ciders and Other Low-Percentage Alcoholic Beverages Available on the Polish Market

Seventy-three samples of alcoholic beverages and juices that were purchased on the Polish market and home-made were analyzed for their elemental profiles. The levels of 23 metals were determined by ICP-MS (Ag, Ba, Bi, Cd, Co, Cr, Li, Mn, Ni, Pb, Sr and Tl), ICP-OES (Al, B, Ca, Cu, Fe, K, Mg, Na, Ti and Zn) and CVAAS (Hg) techniques in twenty-five samples of ciders widely available on the Polish market; six samples of home-made ciders; two samples of juices used in the production of these ciders; and forty samples of low-percentage, flavored alcoholic beverages based on beer. The gathered analytical data confirmed that the final elemental fingerprint of a product is affected by the elemental fingerprint of the ingredients used (apple variety) as well as the technology and equipment used by the producer, and in the case of commercial ciders, also the impact of type of the packaging used was proven. These factors are specific to each producer and the influence of the mentioned above parameters was revealed as a result of the performed analysis. Additionally, the inclusion of the home-made ciders in the data set helped us to understand the potential origin of some elements, from the raw materials to the final products. The applied statistical tests revealed (Kruskal–Wallis and ANOVA) the existence of statistically significant differences in the concentration of the following metals: Ag, Al, B, Bi, Co, Cr, Cu, Fe, K, Li, Mg, Na, Ni, Ti and Zn in terms of the type of cider origin (commercial and home-made). In turn, for different packaging (can or bottle) within one brand of commercial cider, the existence of statistically significant differences for Cu, Mn and Na was proved. The concentrations of all determined elements in the commercial cider from the Polish market and home-made cider samples can be considered as nontoxic, because the measured levels of elements indicated in the regulations were lower than the allowable limits. Moreover, the obtained results can be treated as preliminary for the potential authentication of products in order to distinguish the home-made (fake) from the authentic products, especially for premium-class alcoholic beverages.     

Liquid chromatographic method for quantifying polyphenols in ciders by direct injection

An analytical method for the quantitative determination of the principal phenolic compounds (benzoic acids, hydroxycinnamic acids, 3-phenylpropionic acids, flavanols, procyanidins, dihydrochalcones, quercetin glycosides) in ciders, which successfully employs a RP-HPLC and photodiode-array detection system without prior treatment of the sample, is described. Parameters usually examined in the method validation were evaluated. Good linearity was obtained with correlation coefficients exceeding 0.999 and the detection limits ranged from 0.07 mg/L (p-hydroxybenzoic acid) to 2 mg/L (hydrocaffeic acid). Recoveries ranging between 90 and 104% and the reproducibility of the method was always < 8% (RSD). The method was applied to a set of commercial samples and the results obtained may be helpful to establish a phenolic profile in Asturian cider.     

Application of purge and trap extraction and gas chromatography for determination of minor esters in cider

The validation of a method based on the purge and trap technique combined with gas chromatography-mass spectrometry-flame ionization detection has been carried out in order to apply it to the analysis of ciders. Although 49 compounds were identified, our work was focused on the study of nine minor esters, obtaining recoveries ranging between 93% for ethyl decanoate and 117% for ethyl 3-methylbutyrate, and a precision (RSDs) ranging between 2.2% for hexyl acetate and ethyl decanoate and 10.9% for isopentyl acetate. To demonstrate the feasibility of the procedure, the method was applied to the analysis of commercial ciders.     

Enhanced recovery of Salmonella from apple cider and apple juice with universal preenrichment broth

A comparison was made of the relative efficiencies of Universal Preenrichment (UP) broth and lactose broth for the recovery of a variety of Salmonella serovars from pasteurized and unpasteurized apple cider and pasteurized apple juice. Bulk portions of juice were contaminated with single Salmonella serovars at high and low levels of 0.4 and 0.04 CFU/mL, respectively. The juice was aged for a minimum of 5 days at 2-5 degrees C. On the day analysis was initiated, each of 20 test portions (25 mL) of the contaminated juice was preenriched in UP broth and in lactose broth. The Bacteriological Analytical Manual Salmonella culture method was followed thereafter. For pasteurized apple cider, UP broth recovered significantly (p < 0.05) more Salmonella-positive test portions than did lactose broth (112 and 75, respectively). For unpasteurized apple cider, UP broth recovered significantly more Salmonella-positive test portions than did lactose broth (326 and 221, respectively). For pasteurized apple juice, UP broth recovered more Salmonella-positive test portions than did lactose broth (93 and 81, respectively). However, this difference was not statistically significant. These results indicate that UP broth should replace lactose broth for the analysis of pasteurized and unpasteurized apple cider and pasteurized apple juice.     

气相色谱-串联质谱法结合QuEChERS方法快速检测软包装饮料中8种光引发剂

建立了QuEChERS-气相色谱-串联质谱法快速检测软包装饮料(橙汁、苹果汁、桃汁、菠萝汁和凉茶)中8种光引发剂残留的分析方法。样品以乙腈快速提取,NaCl和无水MgSO4除水后,经N-丙基乙二胺(PSA)和C18粉末净化,用气相色谱-串联质谱(GC-MS/MS)分析,采用多反应监测(MRM)模式检测。在0.01,0.1和0.5 mg/kg的添加水平下,5种软包装饮料的平均回收率为60.4%～99.1%;相对标准偏差(RSD)为1.2%～15.9%;检出限(LOD)为0.2～0.8μg/L。结果表明:本方法简便、快速、安全、价格低廉,重现性良好,可用于软包装饮料中多种光引发剂残留的快速确证检测。     

Evaluation of strontium isotope abundance ratios in combination with multi-elemental analysis as a possible tool to study the geographical origin of ciders

In order to evaluate alternative analytical methodologies to study the geographical origin of ciders, both multi-elemental analysis and Sr isotope abundance ratios in combination with multivariate statistical analysis were estimated in 67 samples from England, Switzerland, France and two Spanish regions (Asturias and the Basque Country). A methodology for the precise and accurate determination of the ⁸⁷Sr/⁸⁶Sr isotope abundance ratio in ciders by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) was developed. Major elements (Na, K, Ca and Mg) were measured by ICP-AES and minor and trace elements (Li, Be, B, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Mo, Cd, Sn, Sb, Cs, Ba, La, Ce, W, Tl, Pb, Bi, Th and U) were measured by ICP-MS using a collision cell instrument operated in multitune mode. An analysis of variance (ANOVA test) indicated that group means for B, Cr, Fe, Ni, Cu, Se, Cd, Cs, Ce, W, Pb, Bi and U did not show any significant differences at the 95% confidence level, so these elements were rejected for further statistical analysis. Another group of elements (Li, Be, Sc, Co, Ga, Y, Sn, Sb, La, Tl, Th) was removed from the data set because concentrations were close to the limits of detection for many samples. Therefore, the remaining elements (Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba) together with ⁸⁷Sr/⁸⁶Sr isotope abundance ratio were considered for principal component analysis (PCA) and linear discriminant analysis (LDA). Finally, LDA was able to classify correctly 100% of cider samples coming from different Spanish regions, France, England and Switzerland when considering Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba and ⁸⁷Sr/⁸⁶Sr isotope abundance ratio as original variables.     

Comprehensive Assessment of Flow and Other Analytical Methods Dedicated to the Determination of Zinc in Water

An original strategy to evaluate analytical procedures is proposed and applied to verify if the flow-based methods, generally favorable in terms of green chemistry, are competitive when their evaluation also relies on other criteria. To this end, eight methods for the determination of zinc in waters, including four flow-based ones, were compared and the Red–Green–Blue (RGB) model was exploited. This model takes into account several features related to the general quality of an analytical method, namely, its analytical efficiency, compliance with the green analytical chemistry, as well as practical and economic usefulness. Amongst the investigated methods, the best was the flow-based spectrofluorimetric one, and a negative example was that one involving a flow module, ICP ionization and MS detection, which was very good in analytical terms, but worse in relation to other aspects, which significantly limits its overall potential. Good assessments were also noted for non-flow electrochemical methods, which attract attention with a high degree of balance of features and, therefore, high versatility. The original attempt to confront several worldwide accepted analytical strategies, although to some extent subjective and with limitations, provides interesting information and indications, establishing a novel direction towards the development and evaluation of analytical methods.     

Determination of Organic Acids in Apple and Cider by Liquid Chromatography with ordinary and narrow-bore columns. A Comparative Study

Abstract

Two narrow-bore columns packed with octadecylsilane of various particle sizes were used to compare their efficiency for the separation of organic acids in apple and cider with that of ordinary columns. The best simultaneous resolution of quinic, malic, shikimic, lactic, acetic, citric and succinic acid was accomplished by using a 100 × 2.1 mm ID, 3-μm Spherisorb ODS-2 column and a phosphate buffer as the mobile phase. This chromatographic system provided a separation efficiency comparable to that afforded by an ordinary 250 × 4.6 mm ID, 5-μm Spherisorb ODS-2 column, plus greater rapidity (30%) and economy, all of which allowed the accurate, precise determination (CV=3%) of the above-mentioned compounds. Finally, the performance of an ordinary UV detector and that of a rapid spectral detector in this type of determination were critically compared.