电感耦合等离子体原子发射光谱法测定氮化钒铁中8种杂质元素

提出了电感耦合等离子体原子发射光谱法测定氮化钒铁中8种杂质元素(铝、铬、镁、锰、磷、钾、钠、硅)的含量。利用X射线荧光光谱法对氮化钒铁进行半定量分析,根据所得结果进行基体匹配,配制标准溶液,制作工作曲线,并用ICP-AES对样品中上述8种元素进行定量测定。试验选择此8种元素的分析线依次为236.705,205.560,285.213,279.079,213.618,769.896,330.298,256.611nm。方法用于生产样品的分析,测定值的相对标准偏差(n=10)在0.29%~4.5%之间。加标回收率在96.0%~105%之间。     

红色花岗石的光谱分析

用电感耦合等离子体原子发射光谱法、Ｘ荧光光谱法测定了印度红、中国红、石棉红等红色花岗石和芝麻白、珍珠白等花岗石的组成，测定了它们的Ｘ射线衍射谱及红外光谱。在中国红、印度红、石棉红、芝麻白和珍珠白花岗石中，含量差别较大的元素有：Ｆｅ、Ａｌ、Ｔｉ、Ｐｂ、Ｃａ、Ｓ、Ｐ、Ｍｇ、Ａｓ、Ｍｎ。中国红、印度红、石棉红花岗石的红色是由于它们含有Ｆｅ的红色矿物而产生的。     

地球化学样品中钒检测方法的对比

地球化学样品中钒的测定方法主要有原子吸收光谱法、等离子体发射光谱法(ICP-AES)、电感耦合等离子体质谱法(ICP-MS)和X射线荧光光谱法.选用国家一级标样,分别用4种方法测定样品含量值,依次对方法检出限、准确度、精密度、加标回收率作比较.经对比,4种方法测定值与推荐值都基本吻合.等离子体发射光谱法检出限低,线性范围更宽,准确度与精密度更好,更适用于地球化学样品中钒批量的测试.     

镍-铬-铁-铌合金中5种元素的测定方法研究

采用电感耦合等离子体原子发射光谱法(ICP-AES)测定Ni-Cr-Fe-Nb合金中Mo、Co、Cu、Mn、Ti等5种微量元素。并对样品溶解方法,基体和共存元素的影响进行了研究。当样品溶液为2.5 mg/mL时,方法标准加入回收率在98.0%~104.5%之间,相对标准偏差10%(n=6)。     

电感耦合等离子体原子发射光谱法测定石墨烯增强铝合金中13种元素

建立测定石墨烯增强铝合金中Mg、Cu、Si、Mn、Zr、Zn、Ga、Ni、Cr、Ti、Fe、V、Be的电感耦合等离子体原子发射光谱方法。称取0.200 0 g样品,用盐酸溶液和硝酸溶液溶解,定容后用中速滤纸过滤掉黑色残留物,在优化的仪器工作条件下对基体匹配的混合标准工作溶液进行测定。13种元素的质量分数在0%～0.100%范围内与光谱强度具有良好的线性关系,相关系数均不小于0.993,检出限为0.000 01%～0.015%。测定结果的相对标准偏差为1.76%～10.21%(n=6),样品加标回收率为95.0%～110.0%。该方法适用于石墨烯增强铝合金中多种元素的测定。     

电感耦合等离子体原子发射光谱法直接测定一种低醇发酵饮料中的微量元素

本文用ICP-AES法,以Sc作内标,不经化学处理直接测定一种低醇发酵饮料中Zn、Ni、Mg、Mn、Fe、Sr、Cu、Ba、Ca和Si等元素,结果与干灰化法或湿消化法基本相符。     

电感耦合等离子体原子发射光谱法测定锆合金中5种元素的含量

提出了电感耦合等离子体原子发射光谱法测定锆合金中锡、铌、铁、铬、镍含量的方法。取样品0.1 g,加入5 mL水、5 mL硝酸和0.5 mL氢氟酸,于100℃加热5 min,用水定容至25 mL。设置仪器射频功率为1 300 W,雾化气流量为0.80 L·min^-1,进样量为2.0 mL·min^-1,测定5种元素在Sn 242.949 nm、Nb 309.418 nm、Fe 259.941 nm、Ni 221.648 nm、Cr 267.716 nm等分析谱线处的响应强度,基质匹配法定量。结果表明：锡、铌的质量浓度在150μg·mL^-1以内,铁、铬、镍的质量浓度在15μg·mL^-1以内分别与对应的响应强度呈线性关系;锡检出限(3s)为16μg·g^-1,其他元素检出限(3s)均低于3.0μg·g^-1;各元素方法重复性的相对标准偏差(n=10)均小于2.0%,加标回收率为99.0%～109%;采用锆合金标准物质SRM360b进行验证,测定值均在认定值的不确定度范...     

电感耦合等离子体原子发射光谱法测定紫砂壶中12种重金属元素

采用电感耦合等离子体原子发射光谱法测定真假紫砂壶中砷、钡、铋、镉、铬、铁、汞、锰、镍、铅、锑和锡等12种重金属元素。紫砂壶样品用盐酸(10+90)溶液浸泡4h,仪器高频功率为1 150 W,辅助气流量0.5L·min-1,载气流量0.5~0.6L·min-1,观察高度9mm。12个元素的质量浓度均在5.00 mg·L-1以内与其发射强度呈线性关系,方法的检出限(3s/k)在0.002~0.010mg·L-1之间。加标回收率在93.0%~105%之间,测定值的相对标准偏差(n=21)在0.24%~0.83%之间。     

微波消解-电感耦合等离子体原子发射光谱法同时测定工业锅炉水中的六种金属元素

应用微波消解,电感耦合等离子体原子发射光谱法同时测定锅炉水中的钙、镁、铜、铁、铝、锌六种金属元素.对射频功率、雾化气流量、分析线进行了优化.各元素校准曲线的相关系数均在0.999 5以上,检出限在0.000 7～0.006 0 mg/L之间.样品分析结果的相对标准偏差为0.48％～6.8％,加标回收率为94.0％～105％.     

电感耦合等离子体原子发射光谱法测定五氧化二钒中19种杂质元素

采用盐酸消解五氧化二钒样品及其中所含可溶性杂质,再以无水碳酸钾与硼酸高温熔融不可溶性杂质,然后以盐酸溶解熔块,合并溶液后以用电感耦合等离子体原子发射光谱法测定杂质元素铌、锆、钛、钨、硅、铝、钼、钴、铬、镍、铜、铅、镉、砷、磷、铁、锰、钙和镁的含量。试验了基体元素和共存元素对测定的干扰,优化各元素的分析谱线,运用同步背景校正消除基体影响。19种元素的检出限在10～225μg.L-1之间,背景等效浓度在5～150μg.L-1之间。方法用于分析五氧化二钒样品,测定结果与其它化学分析方法测定值一致;分析五氧化二钒标准样品(GSBH 42015-96)的测定值与标准值相一致。     

Electroanalytical Approach to Evaluate Antioxidant Capacity in Honeys: Proposal of an Antioxidant Index

A novel electrochemical route to estimate the antioxidant capacity in honey samples is proposed just using flow injection analysis. The analytical strategy involved the selective oxidation of polyphenolic compounds using two different target potentials, +0.8 and +0.5 V, at two different pHs. An oxidation current obtained at the fixed potential was used as an analytical guide of the antioxidant activity of the target honeys. Chemometrics (correlation and principal component analysis, PCA) demonstrated the significance of the electrochemical protocol versus the traditional spectrophotometric ones in the evaluation of antioxidant capacity and revealed the role of detection potential as a screening variable. The proposed protocol is very simple and fast. However, the most relevant merit of the electrochemical procedure is its inherent versatility which allows the evaluation of the antioxidant activity under predesigned controlled oxidation conditions. In addition, since intercept was statistically zero, its corresponding antioxidant content using just a calibration factor is proposed thus simplifying the calibration‐analysis process. As a result, an electrochemical antioxidant index (EAI) is proposed.     

Antioxidant and antimicrobial study of Schefflera vinosa leaves crude extracts against rice pathogens

Plant extracts are one of the best possible sources of bioactive molecules, and are being used globally as an antioxidants and natural antimicrobial compounds. In current study, Schefflera vinosa leaves extract was prepared through Soxhlet extraction procedure using methanol and chloroform as solvents. The extract was investigated for total antioxidant, phenolic and flavonoid contents, free radical scavenging and antimicrobial activities. The free radical scavenging activities were evaluated through 2,2- diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-3-ethylbenzotiazolin-6-sulfonic acid (ABTS) and Ferric-reducing/ antioxidant power (FRAP) assay. The antimicrobial activity of extract was determined through poisoned food method. The methanolic extract has exhibited high antioxidant, phenolic, and flavonoid activities compared to chloroform extract. Similarly, free radical scavenging activities (ABTS, DPPH and FRAP) were higher in methanolic extract. Further, Fourier-Transform Infrared Spectroscopy (FTIR) used to determine the functional group and Gas chromatography-mass spectrometry (GC–MS) to elucidate volatile composition of the crude extract. Different functional group like N-H, O-H, C-O, C-N, C-H, C=O, C≡C and C-O-H presence indicate the existence of many metabolites in the extracts. GC–MS study identified 61 compounds and subsequently, these molecules were screened virtually using DockThor. Furthermore, antimicrobial study was confirmed against rice pathogens like Magnaporthe oryzae (M. oryzae) and Xanthomonas oryzae pv. oryzae (Xoo). Molecular docking study further suggested that phytomolecules (3-Isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris (trimethylsiloxy) tetrasiloxane, and 2-Methoxy-5-methylthiophene) targets Histone Deacetylase (HDAC) of M. oryzae and Peptide Deformylase (PDF) of Xoo, which could inhibit their growth. Hence, this study indicated that Schefflera vinosa extracts could be an important ingredient as an antioxidant as well as antimicrobial agent against rice pathogens.     

氧化石墨的谱学表征及分析

采用改进的Hummers法,通过改变氧化剂用量获得不同氧化程度的氧化石墨,用X射线衍射(XRD)、红外光谱(FTIR)和拉曼光谱(Raman)对产物进行结构和谱学特性的表征,并结合数学分析软件对部分红外和拉曼数据进行分峰拟合。结果表明,石墨经氧化后形成了含有C-OH、-COOH和C-O-C等官能团的石墨层间化合物;氧化剂用量较少时,石墨片层插层氧化不完全,产物的结构中仍存在未被氧化的原石墨周期性结构;随着氧化剂用量的增加,氧化石墨产物的XRD图中原石墨(002)衍射峰逐渐消失,结构中含氧官能团的量逐渐增加,产物的亲水性也逐渐增强;通过对红外光谱的拟合发现,氧化石墨样品在3 198 cm^-1附近有一个红外吸收峰,应归属于C-OH中OH的伸缩振动;随着氧化剂用量的增加,所得氧化石墨产物的拉曼光谱中D峰与G峰的强度积分比R(I_D/I_G)逐渐增大,产物结构中sp²平面域的平均尺寸逐渐减小。     

光电化学技术应用于抗氧化分析的研究进展

在新陈代谢过程中,机体会产生大量以自由基为主要形式的氧化活性物质,而抗氧化剂可以通过电子转移的方式捕获并中和自由基,从而有效抵御自由基引起的细胞损害,以保障和维护人体健康.食品作为人体外源性抗氧化剂的重要来源可以有效补充因体内代谢及体液排出而损失的抗氧化物质,因此对食品中抗氧化物质消除自由基的能力即抗氧化能力的测定和评价具有重要意义.光电化学技术作为一种简单快捷、低成本、低背景且高灵敏度的测定方法,能够有效克服光学法、色谱法和电化学法等传统测试手段在抗氧化容量分析中的不足.本文综述了基于半导体及其复合材料的光电化学传感平台的构建及食品体系抗氧化容量分析的研究进展,评论了多种检测体系的特点并对其研究前景进行了展望.     

Antioxidant behaviour of a nanosilica-immobilized antioxidant in polypropylene

A nanosilica-immobilized antioxidant was prepared and incorporated into polypropylene (PP) by melt compounding. It has been found that the antioxidant efficiency of the nanosilica-immobilized antioxidant was superior to the corresponding low molecular counterpart (AO), based on the measurement of the oxidation induction time (OIT) of PP/nanosilica-immobilized antioxidant and PP/AO compounds containing an equivalent antioxidant component. By paying attention to the changes of carbonyl absorption and tensile strength of PP compounds with thermal oven aging time, it was observed that the thermal oxidative stability of PP/nanosilica-immobilized antioxidant was much higher than that of PP/AO compound during the long-term accelerated thermal aging.     

Quantitative Analysis of Phases Formed During The Oxidation of Covellite (CuS)

A sample of covellite of particle size 45–90 μm was heated in air at 20°C min^–1 in a simultaneous TG-DTA apparatus. The phase compositions of the products at various temperatures were determined quantitatively by XRD and FTIR. By 500°C, 5.8% of Cu₂ O had formed, and this increased to a maximum of 44.8% at 585°C after which it decreased to zero by 750°C. 10% of CuO had formed by 680°C, and then steadily increased to 83.6% at 1000°C. 5.9% of CuO⋅CuSO₄ was found at 610°C, and increased to a maximum value of 79% after which it decomposed completely by 820°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decomposition of borax

Thermal decomposition of borax has been researched by thermal, XRD and FTIR methods as well as SEM microscopy. Study have revealed that it proceeds according to the mechanism of internal reactions in the structure of the precursor as a medium. The following stages of the process have been distinguished: (1) dehydration, (2) internal structure reconstitution—formation of tincalconite, (3) amorphization of crystal structure, (4) gradual dehydroxylation and crystallization of Na₂O·2B₂O₃ inside the amorphous matrix.     

Characterization of Japanese color sticks by energy dispersive X-ray fluorescence,X-ray diffraction and Fourier transform infrared analysis

This work comprises the use of energy dispersive X-ray fluorescence (EDXRF), X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques for the study of the composition of twentieth century traditional Japanese color sticks. By using the combination of analytical techniques it was possible to obtain information on inorganic and organic pigments, binders and fillers present in the sticks. The colorant materials identified in the sticks were zinc and titanium white, chrome yellow, yellow and red ochre, vermillion, alizarin, indigo, Prussian and synthetic ultramarine blue. The results also showed that calcite and barite were used as inorganic mineral fillers while Arabic gum was the medium used. EDXRF offered great potential for such investigations since it allowed the identification of the elements present in the sample preserving its integrity. However, this information alone was not enough to clearly identify some of the materials in study and therefore it was necessary to use XRD and FTIR techniques.     

Nanoemulsions for the Determination of the Antioxidant Capacity of Oils by an Electrochemical Method

The paper describes a rapid and simple method for the evaluation of the antioxidant capacity in oil in water nanoemulsion. This procedure does not require extensive sample treatment and, most important, does not use any organic solvent for dissolution of the fatty matrix. The nanoemulsions were directly injected in a flow injection (FI) system with an electrochemical detector equipped with a glassy carbon working electrode operating amperometrically at a potential of +0.8 V (vs. Ag/AgCl). Results obtained were compared with those obtained by the Oxygen Radical Absorbance Capacity (ORAC) assay.     

Analysis of pigments from Roman wall paintings found in Vicenza

The analysis of about 60 samples of wall paintings was carried out using different chemicophysical techniques: optical microscopy, scanning electron microscopy (SEM) equipped with an EDS microanalysis detector, X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The identified pigments were cinnabar, hematite, red ochre, celadonite, cuprorivaite (Egyptian blue), yellow ochre, goethite and carbon. Only in one case some lead white was found instead. In general, the mortar preparation did not correspond to the complex structure suggested by Vitruvius (De Architectura), but it generally showed a porous layer, with crushed grains under the pigment layer. In certain cases two superposed pigment layers were found: yellow superimposed on both red and pink, black on pink, green on black.