Application of silver nitrate colorimetric method to non-steady-state diffusion test

NT build 443, or profile fitting method, is often used to measure the diffusion coefficient of chloride in concrete. However, this method is quite laborious and needs special equipment. Colorimetric method is a quick and simple method to measure the penetration depth of chloride by spraying 0.1 mol/L silver nitrate solution. The objective of this work is to study the possibility of the use of colorimetric method in the calculation of non-steady-state diffusion coefficient. Twelve concrete mixtures with different supplementary cementitious materials and water-to-cement ratios of 0.35, 0.48 and 0.6 were used for study. According to NT build 443, the concrete specimens were immersed in 165 g/L NaC1 （2.8 mol/L） solution for 42 d. Both water-soluble （convert to free chloride） chloride and acid-soluble chloride at different layers of specimens were measured. The results show that the mean value of free chloride concentration at the color change boundary Cd was 0.306 mol/L. The surface free chloride concentration cs was obtained by profile fitting method, which was 40% lower than the chloride concentration of exposure solution after an immersion period of 42 d. Chloride diffusion coefficients obtained by the colorimetric method was not well correlated with those obtained by profile fitting method.

New Colorimetric Method for Lipases Activity Assay in Microbial Media

A simple, rapid and precise method has been developed for determination of lipase activity in microbial media. The method is based on using phenyl acetate as substrate for lipase and determination of liberated phenol by Folin Ciocalteu reagent. Reaction mixture containing substrate 2.4 ml of phenyl acetate 165 μM in Tris HCl buffer, 0.1 M and pH 7, with 1% (v/v) Triton X-100) and 0.1 ml lipase is incubated at 40?C during 10 minutes and the absorbance was measured at 750 nm. Linearity was observed in the concentration range 0-0.8 g/L lipase.

Assessment of the Presence of Chlorides in Mortar through the Silver Nitrate Colorimetric Spraying Method

This study aims to evaluate the presence of free chlorides by the silver nitrate colorimetric spraying method in mortars made with Portland cement CP II Z-32. In order to make an assessment beyond the qualitative analysis, a calculation of the contaminated areas by free chlorides was performed by measuring the regions using a computer image analysis software （IMAGEJ）. The experimental part of the research involved samples of 5 cm x 10 cm of mortar and 0.1 M solution of silver nitrate in distilled water. The mortar samples were made with cement CP II Z-32 with the following concentrations of chloride incorporated into the mixing water： 0%0, 0.4%, 0.6%, 0.8%, 1.0% and 2.0%, in relation to the mass of cement, totaling 108 samples. The average of percentage results from the contaminated area of the series of samples was respectively 0%, 14.9694%, 19.7444%, 46.0239%, 62.3311% and 96.0083% in relation to the total area, concluding that the method of silver nitrate spraying is applicable and that the white color indicates the presence of chloride ions and other possible aggressive salts to the structure or the concrete.

Automatic Measurement of LED Colorimetric Parameters Based on LabVIEW

In order to accurately and automatically measure the light emitting diode(LED) colorimetric parameters,the design of a measurement system by adopting a high-performance spectrometer and looking-up table method was presented based on the LabVIEW.First,the data of the LED relative spectral power distribution(SPD) were read by the spectrometer to measure LED chromaticity coordinate,and the slopes table were formed by the LED chromaticity coordinate and the equal stimulus point.Then,the CIE1931 chromaticity diagram was divided into 4 different regions to ensure the slopes table that had the character of monotonic decreasing.Finally,the LED dominant wavelength and purity were automatically calculated using the LabVIEW programs.The data of LEDs' colorimetric parameters have demonstrated that the measurement method in this paper can achieve higher precision result.

Direct Colorimetric Detection of Hydrogen Peroxide Using 4-Nitrophenyl Boronic Acid or Its Pinacol Ester

A colorimetric method for the direct determination of hydrogen peroxide in aqueous solution is described. H2O2 stoichiometrically converts 4-nitrophenyl boronic acid or 4-nitrophenyl boronic acid pinacol ester into 4-nitrophenol, which can be quantified by measuring the absorption at 400 nm in neutral or basic media. The reactions proceed fast under basic conditions and complete in 2 minutes to at pH 11 and 80?C. The linear range for the colorimetric method extends beyond 1.0 to 40 μM H2O2, and the limit of detection is ~1.0 μM H2O2. This method offers a convenient and practical process for rapid determination of hydrogen peroxide in aqueous media. Compared to many other techniques in H2O2 detection, this process is a direct measurement of H2O2, and is relatively unaffected by the presence of various salts, metal ions and the chelator EDTA.

基于二氧化铈/羟基氧化铁纳米酶的比色分析法快速检测泡椒凤爪中过氧化氢

采用水热法合成二氧化铈(CeO_(2))修饰的羟基氧化铁(FeOOH),得到纳米材料CeO_(2)/FeOOH。CeO_(2)/FeOOH具有类过氧化物酶活性,可以催化过氧化氢(H_(2)O_(2))分解产生羟自由基(·OH)和超氧阴离子自由基(O2-·),将3,3’,5,5’-四甲基联苯胺(3,3’,5,5’-tetramethylbenzidine,TMB)氧化为蓝色的氧化TMB(oxidized TMB,ox-TMB)。基于此,构建基于CeO_(2)/FeOOH纳米酶的H_(2)O_(2)比色传感器。结果表明:该比色传感器对H_(2)O_(2)显示出高灵敏度响应,检测限为3.92μmol/L,检测范围为10~1000μmol/L。此外,该传感器可用于泡椒凤爪中H_(2)O_(2)的快速检测,其中,H_(2)O_(2)加标回收率为90.59%~93.42%,相对标准偏差≤4.25%,具有灵敏、准确、快速和简便等优势。

Species analysis methods for hydrolysis polymerization of aluminum

Al Ferron timed complex colorimetric method (AFM) and 27 Al NMR spectroscopy method(ANM) were discussed. For the former, the different colorimetric reagent preparation methods' results indicate that there are some differences beteween them, and the combined method can be used as a simplified procedure. For the latter, the small tube method is more accurate. Eventually, the Al 13 (ANM) was compared to the Al b (AFM).

Extraction Optimization of Polysaccharides from Rhizoma Polygonati by Response Surface Methodology and Content Determination

[Objectives]This study aimed to investigate the water extraction-alcohol precipitation technology and content determination method of polysaccharides in Rhizoma Polygonati.[Methods]Taking the content of polysaccharides in the extract as the indicator,the extraction process was optimized using single-factor tests and Box-Behnken Design.The content of polysaccharides extracted was determined by the anthrone-sulfuric acid method.Among the three factors in the test design,the solid/liquid ratio and extraction time had a significant effect(P<0.05,P<0.01),while the extraction temperature had no effect on the content of polysaccharides extracted(P>0.05).[Results]The optimal extraction process for polysaccharides in Rhizoma Polygonati was as follows:liquid/solid ratio 20∶1(mL/g),extraction time 2 h,and extraction temperature 85℃.Under the optimal extraction process,the content of polysaccharides in the extract reached 12.50%.[Conclusions]The extraction process optimized by response surface methodology for polysaccharides in Rhizoma Polygonati is reliable and has practical value,and can be used to guide production practices.

Enzymatic Method for Rapid Determination of Oxalic Acid in Bleaching Filtrates from the Pulp and Paper Industry

Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry. Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method. Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching fiRrates from the pulp and paper industry, The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.

基于茚三酮比色法测定闽产细叶石仙桃总氨基酸含量

目的:优化溶剂回流提取-茚三酮比色法测定福建省不同产地细叶石仙桃中总氨基酸含量。方法:以甘氨酸为对照品,采用茚三酮比色法测定细叶石仙桃中总氨基酸含量;考察不同影响因素对茚三酮法测定细叶石仙桃总氨基酸含量的影响,确定最佳检测条件;在单因素实验基础上,采用L9(34)正交试验考察溶剂用量、溶剂浓度、提取时间及提取次数对细叶石仙桃中总氨基酸提取工艺的影响,并以其为考察指标,优化筛选最佳提取工艺。结果:最佳检测条件为测定波长568 nm、2%茚三酮溶液用量3.0 mL、缓冲液pH值6、缓冲液用量2.0 mL、水浴加热温度80℃、水浴加热时间40 min;最佳提取条件为乙醇浓度85%,乙醇用量35.0 mL,提取时间60 min,提取2次。在所收集到的福建省4个产地的细叶石仙桃中总氨基酸含量由高到低依次为永泰县、上杭县、屏南县、永春县。结论:优选的提取工艺稳定可行,建立含量测定方法简便、准确、重复性好,为细叶石仙桃的质量评价和进一步开发利用提供依据。样品中以永泰县所产的细叶石仙桃质量最佳。

电感耦合等离子发射光谱法与钒钼黄比色法在有效磷含量测定中的应用比较

在农业生产过程中需要对土壤中的有效磷含量以及肥料中的有效磷含量进行检测,为配方施肥提供重要依据,有效磷检测方法的准确性是评判肥料质量高低、实现配方施肥的关键。研究对电感耦合等离子发射光谱法与钒钼黄比色法这两种有效磷检测方法的灵敏度和准确度进行了比较,明确了电感耦合等离子发射光谱法在213.6 nm条件下的磷检出限为0.05 mg/L,钒钼黄比色法在400 nm检测波长的灵敏度最高,检出限为0.32 mg/L。对两种检测方法的检测准确度进行比较,结果表明电感耦合等离子发射光谱法对不同浓度的有效磷检测准确度均高于96%,其准确度受磷浓度的影响小;传统的钒钼黄比色法检测准确度受磷浓度、检测波长影响较大,对磷含量低于5 mg/L的样品检测准确度下降,且低于电感耦合等离子发射光谱法的检测准确度。研究结果认为对于未知浓度范围的样品,钒钼黄比色法在400 nm波长检测条件下的检测结果较为理想。

土壤有效硼提取及测定方法比较

本文提出一种沸水浴提取–ICP-OES测定土壤有效硼的方法,并着重比较分析沸水提取–姜黄素比色法、沸水提取–ICP-OES法、沸水浴提取–ICP-OES法和沸水浴提取–姜黄素比色法对土壤有效硼的测定结果。通过讨论4种方法的测定下限、方法检出限和测定精密度及正确度,及对来自不同地区高中低有效硼含量的6种土壤有效态成分标准物质和4种实际土壤样品的测定比较,探讨4种方法分析测定的关键因素、方法相关性。结果表明,沸水浴提取–ICP-OES法操作简单便捷,方法的检测下限低、干扰因素少、重复性好,可适用于各类型批量样品分析及研究。本研究可为实验室开展土壤有效硼测定方法研究提供借鉴,也可为承担“第三次全国土壤普查”土样检测的实验室在土壤有效硼测定的方法选择、效率提升和质量保证上提供技术支撑。

海南10种市售灵芝水分及指标成分比较研究

目的:研究海南常见的10种市售灵芝质量差异,为地方药材标准起草奠定基础,为进一步开发灵芝提供参考。方法:购买海南常见的10种市售灵芝共30批,分别进行外观性状描述,再参考中国药典(2020版)灵芝标准项下的检验方法,适当优化后,测定灵芝中的水分、三萜和甾醇含量,作为评价灵芝质量的主要指标。结果:方法精密度RSD为1.9%,低、中、高浓度的加标回收率分别为96.4%、95.2%、98.3%,测定灵芝供试品,有1批水分超过17.0%,有4批三萜及甾醇含量低于0.50%。结论:中国药典标准只收录了紫芝和赤芝,其他市售灵芝品种起草标准时可参考药典标准适当修改限度范围。政府应加强监管,逐步规范灵芝市场,修订完善地方药材质量标准,以便于进一步开发和利用灵芝资源。

罗布麻苷提取和检测条件优化及其年限累积效应分析

为优化罗布麻中罗布麻苷的提取和检测条件,明确种植年限对罗布麻苷累积的影响,本试验利用超声波法提取罗布麻苷,用3,5-二硝基苯甲酸-氢氧化钠显色法测定其含量,用铁离子还原/抗氧化能力法(FRAP)和1,1-二苯基-2-三硝基苯肼(DPPH)法检测其抗氧化能力。结果表明:罗布麻苷标准品显色反应液在540 nm下的吸光度与其含量呈良好的线性关系,线性范围为0~1.0 mg/mL(R^(2)=0.992),样品回收率为99.218%,相对标准偏差(RSD)为1.909%。在考察范围内,对提取试剂乙醇浓度、超声时间和料液比进行分析发现,待测样品与95%乙醇的料液比为1∶10(g/mL)、超声提取30 min时,罗布麻苷含量最高,达到639.34μg/g。种植3、7、10年的罗布麻不同部位罗布麻苷含量差异显著,依次为7年叶>3年叶>10年叶>3年茎>7年根>10年根>3年茎>7年根>10年茎。年限间比较,种植7年的罗布麻具有较高的罗布麻苷含量,为626.25μg/g,抗氧化能力表现为7年>3年>10年,且3个种植年限间均有较强的DPPH自由基清除能力。相关性分析表明,种植7年的罗布麻中罗布麻苷含量与抗氧化能力呈正相关。本研究结论可为罗布麻苷提取及相关功能性产品开发提供依据。

激光打印制备可便携检测Cu^(2+)的纸基微流控比色传感器

现场检测水环境中的铜离子浓度需要一种快速便捷且灵敏度高的方法.该研究基于激光打印方法将碳粉印制在定性滤纸上构建微流控通道,使用双环己酮草酰二腙功能化定性滤纸,组装为纸基比色传感器可用于水环境中铜离子的检测.实验表明,通过智能手机与开发的颜色信息提取程序,纸基微流控比色传感器在饮用水中Cu^(2+)的检出限(LOD)为0.11 mg·L^(-1),定量限(LOQ)为0.35 mg·L^(-1).传感器成功应用于河水样品检测,对大于定量限的样本回收率在84.00%~110.73%之间.所制备的比色传感器制造步骤简便,具有较好的稳定性,实现了低成本的快速检测,显示其在现场环境监测的应用潜力.

不同熟化方式下甘薯果胶含量与质构相关性分析

目的比较分析不同品种的甘薯在不同熟化方式下果胶含量的差异以及与质构指标的相关性。方法采用咔唑比色法对甘薯中的可溶性果胶含量和原果胶含量进行测定,并测定了生、熟薯块的质构指标。结果不同甘薯品种的生、烤和蒸薯中均含有可溶性果胶和原果胶,且各品种的果胶含量存在差异。在生薯的果胶含量中,原果胶含量最高;在烤薯和蒸薯的果胶含量中,可溶性果胶含量最高。参试品种的生薯、烤薯和蒸薯的质构指标间差异性较大。在生薯中,冀元2号的硬度最高,冀元1号的黏附性最大,冀元2号的胶黏性最大;烤薯中冀薯9号的硬度最大,慧谷2号的弹性最大,普薯32号的内聚性最高;蒸薯中慧谷2号的硬度最大,哈密的弹性最大,冀元1号的胶黏性最大。相关性分析结果表明,质构指标与可溶性果胶含量、原果胶含量之间存在着较好的相关性:生薯的原果胶含量与干物率呈极显著正相关,与黏附性呈极显著负相关;烤薯可溶性果胶含量与原果胶含量之间呈显著负相关;蒸薯的可溶性果胶含量与弹性呈显著正相关,原果胶含量与回复性呈显著负相关。结论该研究结果可为甘薯品种适宜加工方式的选择和评价,以及后续甘薯新品种的选育提供参考。

A novel colorimetric method for field arsenic speciation analysis

Accurate on-site determination of arsenic （As） concentration as well as its speciation presents a great environmental challenge especially to developing countries. To meet the need of routine field monitoring, we developed a rapid colorimetric method with a wide dynamic detection range and high precision. The novel application of KMnO4 and CHaN2S as effective As（III） oxidant and As（V） reductant, respectively, in the formation of molybdenum blue complexes enabled the differentiation of As（III） and As（V）. The detection limit of the method was 8 ~tg/L with a linear range （R2 = 0.998） of four orders of magnitude in total As concentrations. The As speciation in groundwater samples determined with the colorimetric method in the field were consistent with the results using the high performance liquid chromatography atomic fluorescence spectrometry, as evidenced by a linear correlation in paired analysis with a slope of 0.9990- 0.9997 （p 〈 0.0001, n = 28）. The recovery of 96%-116% for total As, 85%-122% for As（III）, and 88%-127% for As（V） were achieved for groundwater samples with a total As concentration range 100-800 μg/L. The colorimetric result showed that 3.61 g/L As（III） existed as the only As species in a real industrial wastewater, which was in good agreement with the HPLC-AFS result of 3.56 g/L As（Ⅲ）. No interference with the color development was observed in the presence of sulfate, phosphate, silicate, humic acid, and heavy metals from complex water matrix. This accurate, sensitive, and easy-to-use method is especially suitable for field As determination.

基于银纳米簇比色传感器快速检测水果维生素C的方法

为提升水果品质分析效率,建立了基于银纳米簇比色传感器快速检测水果维生素C的方法。该方法以偏磷酸溶液萃取水果中的维生素C,以石墨化炭黑吸附干扰物质。以硝酸银水溶液和聚甲基丙烯酸钠水溶液混合加热搅拌4 h制备聚甲基丙烯酸修饰的银纳米簇材料,银纳米簇为球形,银纳米簇的平均直径为1 nm,加入维生素C以后,维生素C还原银离子从而增大了银纳米簇的尺寸并改变了银纳米簇溶液的光学性能,通过溶液颜色在感观上深浅变化和RGB色彩模式下蓝色值变化可实现维生素C含量的裸眼半定量分析和手机定量分析。在优化得到最佳检测条件后,结果表明,该检测方法可检出的维生素C最小含量为0.03 mg/kg,可定量的维生素C最小含量为0.1 mg/kg;该检测方法对葡萄糖、果糖、蔗糖、钙离子、锌离子、钾离子、叶酸等物质表现出了较好的抗干扰能力;该检测方法成功应用于橙、葡萄和梨果实维生素C的分析。将银纳米簇材料应用于水果的品质分析,有助于加快检测速度,降低检测成本,实现水果的精准快速分级。

厨余垃圾干式厌氧发酵过程中的挥发性脂肪酸测定方法研究

在厨余垃圾干式厌氧发酵过程中,挥发性脂肪酸浓度是一个重要的监测指标,通过每天测定挥发性脂肪酸浓度可以了解厌氧发酵系统的运行情况。分别采用Nordmann滴定法、气相色谱法和比色法测定了厨余垃圾干式厌氧发酵过程中挥发性脂肪酸的浓度。试验结果表明,由于比色法待测样品预处理过程较多等原因,导致采用比色法测定挥发性脂肪酸浓度的结果较不稳定。气相色谱法操作繁琐、样品预处理过程较多,单个样品试验时间较长,适用于需要测定单种挥发性脂肪酸浓度的情况。Nordmann滴定法能够克服这些缺点,兼具有操作简单、精密度高等优点,因此建议厨余垃圾厌氧发酵过程中挥发性脂肪酸的浓度优先使用Nordmann滴定法进行测定。

基于纳氏试剂比色法的印染行业污水氨氮测定与优化

为探究印染行业污水氨氮的准确测定方法,本次研究以纳氏试剂比色法为基础,参考已有研究资料对基于纳氏试剂比色法的印染行业污水氨氮测定实验流程进行了探讨,并通过实验确定了最优的实验参数组合为反应体系的pH为10,显色时间为10 min,且纳氏试剂的用量为1.0 mL。基于此实验参数组合做进一步实验后显示,其RSD和加标回收率等指标均较优,表明本次实验方法具有较高的精密度与可行性。