共查询到19条相似文献,搜索用时 203 毫秒
1.
不同产地黄芪的聚类分析 总被引:5,自引:0,他引:5
用ICP-AES测定15个不同产地的黄芪中的14种微量元素,以其含量为指标,进行因子分析,提取7个特征元素,并以特征指标进行样品的谱系聚类分析,把不同产地的黄芪分类,为地道性中药材的鉴别提供可靠方法。 相似文献
2.
铝灰中的氟化物是铝灰中的环境危害因子.使用X射线荧光光谱(XRF)法、X射线衍射(XRD)法对15份铝灰样品进行了元素及物相组成检测,使用SPSS 25.0对数据进行因子分析和聚类分析,将15份样品分成四类,从每类中选择1~2个样品,共选取5份样品作为代表进行后续实验.使用离子色谱法和氟离子选择电极法对铝灰浸出液中氟离... 相似文献
3.
为研究中药鳌甲中元素的分布规律及其与药材产地之间的关系,探讨鳌甲中无机元素的特征,采用电感耦合等离子体质谱法(ICP-MS)测定了10批鳖甲样本中10种无机元素含量,根据元素含量的高低分布状态建立了鳌甲药材相关的无机元素指纹图谱,运用"总体特征分布分析-主成分与系统聚类分析结合-因子分析"的三级分析方法,对选取的特征元... 相似文献
4.
波长色散X射线荧光光谱法分析小麦籽粒中矿质元素 总被引:1,自引:0,他引:1
《分析试验室》2017,(6)
采用波长色散X射线荧光光谱法(WDXRF)对小麦籽粒中Mn,Fe,Cu,Zn,Ca,Mg,P,K和S含量进行测定,讨论了不同产地小麦籽粒中矿质元素含量。运用主成分分析提取2个主成分、建立了主成分方程,利用聚类分析对小麦产地进行识别。结果表明,不同产地小麦籽粒中矿质元素含量差异明显。前2个主成分累积方差贡献率达到82.0%,黑龙江和内蒙古产地的小麦籽粒样品品质较优。在阈值为3.5的水平上将小麦籽粒样品聚为6类,可以实现小麦籽粒样品产地的初步鉴别。用WDXRF法结合化学计量学方法可揭示小麦籽粒样品中矿质元素含量差异及进行产地识别。 相似文献
5.
基于元素指纹的白术产地溯源及其与土壤的相关性研究 总被引:1,自引:0,他引:1
本研究主要采用电感耦合等离子体质谱仪(ICP-MS)等手段测定5个产地白术41种矿质元素含量和土壤41种化学成分指标, 结合聚类分析法、偏最小二乘判别分析(PLS-DA)法和Pearson相关性分析研究了不同产区白术矿质元素特征以及不同产区土壤因子的差异, 并对它们的相关性进行了探讨. 结果表明, 采用无监督的聚类分析和有监督的PLS-DA均能正确判别不同产地的白术和土壤, 其中稀土元素在浙江白术与土壤间呈正相关. 另外, Li、V、Mn、Co、Cu、Rb、Cd、Cs、Ba等微量元素是白术产地溯源的关键因素. 研究发现在白术生产实践中可以通过适量控制种植地的土壤湿度、增施特定肥料等措施调控白术矿质元素含量. 本研究将为解释道地白术的品质形成机制, 保证白术药效质量的有效性提供一定帮助. 相似文献
6.
植物类中药中微量元素的因子分析和聚类分析 总被引:40,自引:0,他引:40
尝试利用化学计量学方法探讨微量元素含量与中药药性的相关性。对105味植物类中药42种微量元素测定数据用因子分析和聚类分析进行了多因素分析。因子分析证实了一个10因子模型合理解释这些微量元素间的相关关系;样本聚类分析证明了105株中药合理地聚类成不同组; 相似文献
7.
建立电感耦合等离子体质谱法(ICP-MS)测定不同产地和批次地龙药材中铅(Pb)、砷(As)、汞(Hg)、镉(Cd)、铜(Cu)5种重金属元素的含量.采用微波消解进行样品前处理,结果表明:5种重金属元素的线性关系良好(r≥0.999 6),平均回收率在92.8%~95.2%范围内,方法的检出限在0.001 0~0.092 mg/kg范围内.方法灵敏度高,重复性好,方法准确.不同产地和批次的样品中5种重金属元素均有检出.地龙药材中Pb、As、Hg、Cd、Cu这5种重金属元素需要重点监控. 相似文献
8.
9.
常见茶叶中14种元素含量分析及重金属风险评价 总被引:1,自引:0,他引:1
采集传统名茶地标产品样品各3种为实验样品,通过ICP-OES和ICP-MS对样品进行K、Ca、Mg、Mn、B、Cu、Fe、Ni、Zn、Cr、Co、Cd、As、Pb等14种元素的含量测定。利用单因素方差分析、主成分分析、污染评价等方法,对茶叶无机元素含量进行分析和污染评价,并对污染来源进行了研究。结果表明,不同产地茶叶样品中的K、Ca、Mg、Mn、Fe等元素含量差异较大;食品及茶叶安全限量元素Cd、Cr、Pb、As等实测值均未超过国家标准限值;部分元素之间具有正相关性,如Cu与Cd, Cu与Ni, As与Ni两两之间关联性较强;从主成分分析看出Cu、Cd、As和Ni为PC1代表因子,K和Fe分别为PC2和PC3的代表因子,PC1主要代表了金属冶炼、工业排放和垃圾焚烧等方面的贡献,PC2和PC3分别代表了肥料施放和茶叶加工等方面的贡献。 相似文献
10.
白卡奴鸽动脉粥样硬化模型微量元素谱的计算机多元分析 总被引:1,自引:0,他引:1
用ICP-AES测定了白卡奴鸽动脉粥样硬化模型和对照组的器官和组织中19种元素含量,通过因子分析,取得一系列因子得分图,结果表明,动脉粥样硬化和对照组样品点分布在不同区域,且可分辨。 相似文献
11.
Araújo AS da Rocha LL Tomazela DM Sawaya AC Almeida RR Catharino RR Eberlin MN 《The Analyst》2005,130(6):884-889
After just simple degassing, dilution, pH adjustment and direct flow injection, characteristic fingerprint spectra of beer samples have been obtained by fast (few seconds) electrospray ionization mass spectrometry (ESI-MS) analysis in both the negative and positive ion modes. A total of 29 samples belonging to the two main beer types (lagers and ales) and several beer subtypes from USA, Europe and Brazil could be clearly divided into three groups both by simple visual inspection of their ESI(+)-MS and ESI(-)-MS fingerprints as well as by chemometric treatment of the MS data. Diagnostic ions with contrasting relative abundances in both the positive and negative ion modes allow classification of beers into three major types: P = pale (light) colored (pilsener, pale ale), D = dark colored (bock, stout, porter, mild ale) and M = malt beer. For M beers, samples of a dark and artificially sweetened caramel beer produced in Brazil and known as Malzbiers were used. ESI-MS/MS on these diagnostic beer cations and anions, most of which are characterized as arising from ionization of simple sugars, oligosaccharides, and iso-alpha-acids, yield characteristic tandem mass spectra adding a second and optional MS dimension for improved selectivity for beer characterization by fingerprinting. Direct ESI-MS or ESI-MS/MS analysis can therefore provide fast and reliable fingerprinting characterization of beers, distinguishing between types with different chemical compositions. Other unusual polar components, impurities or additives, as well as fermentation defects or degradation products, could eventually be detected, making the technique promising for beer quality control. 相似文献
12.
Chiva-Blanch G Urpi-Sarda M Rotchés-Ribalta M Zamora-Ros R Llorach R Lamuela-Raventós RM Estruch R Andrés-Lacueva C 《Journal of chromatography. A》2011,1218(5):698-705
Beer is one of the most commonly consumed undistilled alcoholic beverages in many countries. In recent studies, the stilbenes resveratrol and piceid have been found in some hop varieties which are used in the production of beer. Therefore, they could be transferred to beer. The aim of the present work was to validate a method to study the potential content of trans- and cis-resveratrol and piceid in 110 commercial beers from around the world. The resveratrol and piceid contents of 110 beers were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after a solid-phase extraction (SPE) using optimized and validated procedures for the beer matrix. The beer matrix effect was also studied. Stilbenes were found in quantifiable amounts in 92 beers, while concentrations below the limit of quantification (LOQ) were found in 18 beers. Resveratrol was found in the range of 1.34-77.0μg/L in 79% of the beers analyzed, and piceid was found in the range of 1.80-27.3μg/L in only 33% of them. The mean of total resveratrol in all the beers was 14.7±20.5μg/L. The content of resveratrol has been compared with other resveratrol containing foods. A serving of beer contains similar amounts of stilbenes as berries, less than chocolate and grape products but more than pistachios, peanuts or tomatoes. Overall, beer is one of the products with the lowest levels of total resveratrol (μg/L), and despite its high consumption it should not be considered as a representative source of resveratrol. 相似文献
13.
A liquid chromatography (LC) method is described for the simultaneous analysis of iso-alpha-acids and reduced iso-alpha-acids in beer. Volatile mobile phase additives were selected to enable hyphenation to mass spectrometric (MS) operated in the atmospheric pressure chemical ionization (APCI) mode. Contrary to other recent LC optimization procedures for the same compounds, an alkaline pH was selected hereby improving peak shape and selectivity. Both UV and MS detection are sensitive enough to analyze beers without sample pre-concentration. All major bitter acids are separated within 65 min with exception of cis-dihydroisoadhumulone, which co-elutes with trans-isocohumulone. Due to the selectivity of the MS, these compounds could be differentiated according to their m/z value. The performance in terms of quantification of bitter acids by LC-UV and LC-MS are compared for standard solutions and a selection of 14 beers. 相似文献
14.
A very simple method for determination of trace amount of Cu, Mn and Fe in beer by inductively coupled plasma spectrometry
(ICP-AES) was developed. The beer was directly introduced into the plasma, without dilution or adding of reagents, via a conventional
V-groove nebulizer. The only sample preparation used was degassing of the beer to remove CO2. By optimizing the ICP-AES parameters (RF power and Nebulizer gas flow rate) and by the appropriate choice of wavelengths
for measurements, sufficient accuracy for the determination of the trace metals was obtained. Various types of beers were
analysed by the direct ICP-AES method and for comparison, also with two other methods: by GFAAS and ICP-AES after decomposition.
No significant difference was found for Cu and Mn (ANOVA, 95% confidence level) using the three methods. This was normally
also the case for Fe; only in one case did the result of Fe by the direct method deviate from the other methods (10% lower
results). The limit of detection for the direct method was estimated to 1.1, 0.3, and 1.1 ng mL−1 for Cu, Mn, and Fe, respectively. 相似文献
15.
Xavier Cetó Juan Manuel Gutiérrez Aitor Mimendia Francisco Céspedes Manel del Valle 《Electroanalysis》2013,25(7):1635-1644
This paper deals with the application of a voltammetric electronic tongue (ET) towards beers classification. For this purpose, samples were analyzed using cyclic voltammetry without performing any sample pretreatment, albeit its dilution with distilled water. The voltammetric signals were first preprocessed employing Fast Fourier Transform (FFT). Then, using the obtained coefficients, responses were evaluated using three different clustering techniques: Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS‐DA) and Linear Discriminant Analysis (LDA). In this case, the ET has demonstrated a good capability to correctly discriminate and classify the different beer samples according to its type (Lager, Stout and IPA) and manufacture process (commercial and craft). 相似文献
16.
Insights on beer volatile profile: Optimization of solid‐phase microextraction procedure taking advantage of the comprehensive two‐dimensional gas chromatography structured separation 下载免费PDF全文
Cátia Martins Tiago Brandão Adelaide Almeida Sílvia M. Rocha 《Journal of separation science》2015,38(12):2140-2148
The aroma profile of beer is crucial for its quality and consumer acceptance, which is modu‐lated by a network of variables. The main goal of this study was to optimize solid‐phase microextraction experimental parameters (fiber coating, extraction temperature, and time), taking advantage of the comprehensive two‐dimensional gas chromatography structured separation. As far as we know, it is the first time that this approach was used to the untargeted and comprehensive study of the beer volatile profile. Decarbonation is a critical sample preparation step, and two conditions were tested: static and under ultrasonic treatment, and the static condition was selected. Considering the conditions that promoted the highest extraction efficiency, the following parameters were selected: poly(dimethylsiloxane)/divinylbenzene fiber coating, at 40ºC, using 10 min of pre‐equilibrium followed by 30 min of extraction. Around 700–800 compounds per sample were detected, corresponding to the beer volatile profile. An exploratory application was performed with commercial beers, using a set of 32 compounds with reported impact on beer aroma, in which different patterns can be observed through the structured chromatogram. In summary, the obtained results emphasize the potential of this methodology to allow an in‐depth study of volatile molecular composition of beer. 相似文献
17.
Determination of elemental fingerprint profile of 40 commercial beer samples was performed using inductively coupled plasma–mass
spectrometry combined with principal component analysis and receiver operating characteristic (ROC) analysis. Fourteen trace
elements, 51V, 52Cr, 59Co, 60Ni, 75As, 82Se, 95Mo, 111Cd, 115In, 121Sb, 133Cs, 208Pb, 209Bi, and 238U, were monitored. All 40 beer samples are distinguishable by using the proposed method. ROC analysis showed that individual
beer samples can be correctly identified via the magnitude of its correlation coefficient with respect to the other beers
with low false positive rate. The obtained results suggested that the elemental fingerprint technique is feasible for sample
differentiation and comparison. 相似文献
18.
Vera L Aceña L Guasch J Boqué R Mestres M Busto O 《Analytical and bioanalytical chemistry》2011,399(6):2073-2081
An electronic nose based on coupling of headspace (HS) with a mass spectrometer (MS) has been used in this study to classify
and characterize a series of beers according to their production site and chemical composition. With this objective, we analyzed
67 beers of the same brand and preparation process but produced in different factories. The samples were also subjected to
sensory evaluation by a panel of experts. Linear discriminant analysis (LDA) was used as the classification technique and
stepwise LDA based on Wilk’s lambda criterion was used to select the most discriminating variables. To interpret the aroma
characteristics of the beers from the m/z ions obtained, score and loading bi-plots were obtained by applying canonical variables. Because the beers analyzed were
marketed with the same name and brand, we expected to be working with the same product irrespective of its origin. However,
results from both sensory evaluation and use of the e-nose revealed differences between factories. With the e-nose it was
possible to relate these differences to the presence (and abundance) of characteristic ions of different compounds typically
found in beer. These results demonstrate that the HS–MS e-nose is not only an aroma sensor capable to classify and/or differentiate
samples but it can also provide information about the compounds responsible for this differentiation. 相似文献
19.
A flow injection analysis with integrated amperometric alcohol dehydrogenase biosensor and a handheld Mira‐DS Raman spectrometer have been compared for the determination of ethanol in different samples of alcoholic drinks. The biosensor was constructed from the commercial screen‐printed carbon electrode as amperometric transducer and covered by a thin layer comprising alcohol dehydrogenase, reduced single‐layer graphene oxide, rhodium(IV) dioxide, and glutaraldehyde. Both assemblies were tested on analysis of plum brandy, white rum, vodka, white and red wines, strong dark beer, and non‐alcoholic beer. The two principally different analytical methods were critically compared and some limitations found, especially in case of analysis of red wine and beers. Finally, some future improvements of both analytical tools under test outlined. 相似文献