数码比色法测定环境及生物样品中的氰化物浓度

在传统氰化物检测方法的基础上,提出了一种新的方法—数码比色法。在一定条件下,苦味酸与氰化物生成黄色化合物,用数码相机对显色溶液拍照,通过数码比色,进行灰度处理,照片的三原色值与氰化物的浓度成线性关系,可以直接分析出其氰化物的浓度。对唾液样品测定,其回收率为98.18%,对照品测定的相对标准偏差RSD为1.5%。研究结果表明,数码比色法具有准确度和精密度都比较理想,方便快速、环境友好等特点。     

数码成像比色法测定补铁剂中铁元素含量的实验研究

利用数码成像原理,使用手机拍照,并用Photoshop 7.0软件处理图片得到标准溶液图片的灰度值,绘制标准曲线,进而测定补铁剂中铁元素的含量。本实验操作简便,用时短,精确度高。在中学引入数码成像比色法,不仅可以扩展定量实验的范围,还能凸显数码分析技术在化学学科中的应用,适合高中阶段开展特色兴趣实验。     

基于智能手机的数码荧光比色法测定银离子含量*

基于STEM教育理念,通过合作学习和项目探究等方法,探索出一种基于智能手机和Color Grab软件测定银离子含量的数码荧光比色法。该方法具有较高的科学性、新颖性、准确性和简便性,也极大地拓展了比色法的适用范围。智能手机等数码产品具有广泛性、系统的协同性和操作的便捷性等优点,利用其在中学阶段开展化学教学实验及课外探究实验,能为中学化学实验教学改革提供新思路。     

“同离子效应对醋酸电离平衡的影响”趣味化及可视化实验设计*

以醋酸为例,运用液膜自然扩散法从定性角度出发,通过颜色区分度与数码技术探究同离子效应影响下的电离平衡的动态变化过程,卡通画式的液滴展现化学实验的趣味性,同时实现电离平衡过程粒子漫步化的可视化目标,实验与科技有效融合使得变化观念与平衡思想的学科素养得到完美体现,适合教师在演示实验教学中使用。但因学生对颜色感知能力有所不同,也为了更准确地判断同离子效应中浓度的影响因素,运用数码成像比色法从定量角度出发,借助智能手机和APP进行图像采集、数据处理与分析,最终实验结果以简洁的曲线图呈现,突出实验的科学性和系统性的高阶性要求。     

数码成像比色法测定水样中的总磷

在酸性介质中,磷酸二氢钾与钼酸铵、酒石酸锑钾及抗坏血酸作用,生成蓝色的络合物。随着磷酸二氢钾浓度的增加,溶液颜色加深,其数码成像的RGB值亦随着磷酸二氢钾浓度的增加而增加,由此建立数码成像比色法(DIC)测定水样中总磷的新方法。考察了DIC法的影响因素和最佳反应条件。与钼酸铵分光光度法对照,该方法简单,快速。用于实际水样的测定,相对标准偏差为1.8%~3.4%,回收率为99.7%~102.5%,结果与分光度法一致。     

[ZnN(CH2CH2NH2)2(CH2CH2N=CHC6H4O)]·Pic的合成与晶体结构

在不加任何碱的条件下,三[2-(亚水杨基胺)乙基]胺与苦味酸锌[Zn(Pic)26H2O]在乙醇中反应,得到了较为少见的多胺单缩合西夫碱配体的配合物[ZnN(CH2CH2NH2)2(CH2CH2N=CH-C6H4O)]Pic。化学式为C19H23N7O8Zn,Mr=542.81,晶体属三斜晶系,空间群为P,晶胞参数为a=0.7494(3),b=1.1917(5),c=1.3142(6)nm,a=78.111(7),b=79.093(7),g=78.577(7),V=1.1121(8)nm3,Dc=1.621g/cm3,m(MoKa)=1.167mm-1,Z=2,F(000)=560,在1.602s(I)的可观测点为2433个,最终偏离因子R=0.0555,wR=0.1139。配合物中Zn(II)与配体的4个N原子和1个O原子配位形成变形的三角双锥结构,桥头N和O为锥顶,4个配位N中桥头N与金属离子的配位作用最弱。晶体通过p-p堆积和分子内、分子间的氢键作用形成二维层状超分子结构。     

数码成像比色法探究反应物浓度对化学反应速率的影响

利用数码成像比色法探究反应物浓度对化学反应速率的影响,采用紫红色溶液互补光"绿"通道的亮度值-时间的曲线变化表征反应物浓度与化学反应速率的关系。同时也利用分光光度计研究反应物浓度与反应速率的关系,测出透光率-时间的曲线变化。从实验结果比较分析,用数码成像比色法探究反应物浓度对化学反应速率的影响是非常简便可行的方法,同时让学生使用随身所带的电子产品开展实验研究,不仅使实验教学具有趣味性和科学性,而且能更好地培养学生的创新潜质。     

手机数码比色法测定土壤中总磷含量

基于在酸性介质中,磷酸二氢钾(KH2PO4)与钼酸钠及抗坏血酸作用,生成蓝色的络合物,溶液的颜色随着KH2PO4浓度的增加而逐渐变浅,并呈现一定颜色梯度的原理,提出了使用手机数码比色法测定土壤中总磷含量的分析新方法。方法的相对标准偏差(RSD)为1.2%,对样品进行加标回收实验,加标回收率在102%~103%。方法方便快捷,成本低,适合现场分析,是一种农民自行测定土壤中总磷含量的新方法。     

氰化物分析研究进展

介绍氰化物常用的场外分析和现场检测方法,对实验室(场外)常用分析方法如化学滴定法、分光光度法、色谱法、波谱法等以及现场快速检测方法如目视比色法、分光光度计法等进行了综述,并结合实际需求,总结了不同方法的特点,展望了氰化物检测方法的未来发展趋势。     

[Mn(SCZ)3](PA)2·H2O的晶体结构及热分解机理

制备得到了新配合物[Mn(SCZ)3](PA)2H2O,用元素分析和FT-IR对其结构进行了表征。用X-射线单晶衍射对其结构进行了测定,采用MoKa射线、l=0.071073nm,收集到5054个独立衍射点,其中的3812个可观测衍射点用于结构计算和修正。晶体属三斜晶系,P空间群,化学式C15H21N15O18Mn,Mr=754.41。晶体学参数a=0.7991(2),b=1.2968(3),c=1.4791(2)nm,a=72.78(1),b=84.36(1),g=81.80(2),V=1.4466(5)nm3,Z=2,Dc=1.732g/cm3,F(000)=770,S=1.07,m(MoKa)=0.565mm-1。最终偏离因子R=0.0634,wR=0.1292。中心Mn2+为六配位畸变八面体构型,它同时与3个SCZ分子配位,形成3个稳定的平面畸变五员环。苦味酸根阴离子通过静电引力和氢键与配位阳离子结合。分子间通过大量氢键在整个空间构成无限延伸的三维网状结构。[Mn(SCZ)3](PA)2H2O的热分解有2次剧烈的放热质量损失过程,热分解最终产物为MnO。     

DDTC-Na-based colorimetric chemosensor for the sensing of cyanide in water

Sodium diethyldithiocarbamate (DDTC-Na) was demonstrated to be a new colorimetric cyanide chemosensor by utilizing an indirect trick. First, some copper ions were added to the colorless aqueous solution of DDTC-Na. Then, the resultant brown solution was studied upon the addition of different anions, including Cl⁻, I⁻, IO₃⁻, SO₄²⁻, NO₂⁻, Br⁻, H₂PO₄⁻, F⁻, SCN⁻, HSO₄⁻, ClO₄⁻ and CN⁻. It was observed by naked eyes that the brown solution changed to colorless immediately after the addition of the trace cyanide, but there were no changes towards other anions, making DDTC-Na a good selective cyanide chemosensor in pure water. Supported by the National Natural Science Foundation of China (Grant Nos. 20674059 & 20402011)     

A highly sensitive and selective fluorescent probe for cyanide based on the dissolution of gold nanoparticles and its application in real samples

We report a simple fluorescence method for detection of cyanide sensitively and selectively based on the dissolution of polymer-coated gold nanoparticles by cyanide. The lowest concentration for quantification of cyanide ions was 3.0×10(-7) M, and other common anions nearly have no influence. Furthermore, several real water samples spiked with cyanide, including local groundwater, tap water, boiled water, and lake water, were analyzed, and the experimental results demonstrated that our sensing system worked well in the above water samples, with a good linear correlation.     

巯基乙酸-纳米银比色传感快速检测水样中的Pb2+

利用巯基乙酸含S配位原子,能与纳米银形成Ag-S配位键吸附在纳米银表面,防止纳米银团聚,Pb²⁺的引入导致纳米银溶胶发生团聚现象,溶液的颜色由亮黄色变灰红色,由此建立了测定痕量Pb²⁺的比色方法。在优化的实验条件下,Pb²⁺的线性范围为0.1~5.0×10^-6mol/L (R²=0.9956),裸眼检出限为0.5μmol/L。此方法用于环境中Pb²⁺的检测,其回收率在90%~110%之间,RSD <2.5%。     

A rapid responsive and highly selective probe for cyanide in the aqueous environment

A colorimetric and fluorescent cyanide probe based on 7-(trifluoroacetamino)coumarin has been prepared. This structurally simple probe displays rapid response and high selectivity for cyanide over other common anions in the aqueous solution. The sensing of cyanide was performed via the nucleophilic attack of cyanide anion to carbonyl of the probe with a 1:1 binding stoichiometry, which could be confirmed by Job’s plot, ¹H NMR, and MS studies. DFT/TDDFT calculations support that the fluorescence enhancement of the probe is mainly due to the ICT process improvement. The detection limit of the fluorescent assay for cyanide is as low as 0.3 μM in a rapid response of less than 30 s. Thus, the present probe should be applicable as a practical system for the monitoring of cyanide concentrations in aqueous samples.     

A sensitive and practical colorimetric test for polymer-supported hydroxyl and thiol groups

A new sensitive and practical colorimetric test for solid-supported hydroxyl and thiol groups is described. The assay is based on the direct labeling with low amounts of commercially available NF31 in the presence of DMAP at room temperature, resulting in easily detectable red beads.     

Thiourea based novel chromogenic sensor for selective detection of fluoride and cyanide anions in organic and aqueous media

Novel chromogenic thiourea based sensors 4,4′-bis-[3-(4-nitrophenyl) thiourea] diphenyl ether 1 and 4,4′-bis-[3-(4-nitrophenyl) thiourea] diphenyl methane 2 having nitrophenyl group as signaling unit have been synthesized and characterized by spectroscopic techniques and X-ray crystallography. The both sensors show visual detection, UV-vis and NMR spectral changes in presence of fluoride and cyanide anions in organic solvent as well as in aqueous medium. The absorption spectra indicated the formation of complex between host and guest is in 1:2 stoichiometric ratios.     

A novel label-free colorimetric assay for DNA concentration in solution

Optical devices were fabricated by sandwiching a “monolithic” poly(N-isopropylacrylamide-co-N-(3-aminopropyl) methacrylamide hydrochloride) (pNIPAm-co-APMAH) microgel layer between two semitransparent Au layers. These devices, referred to as etalons, exhibit characteristic multipeak reflectance spectra, and the position of the peaks in the spectra primarily depends on the distance between the Au surfaces mediated by the microgel layer thickness. Here, we show that the positively charged microgel layer can collapse in the presence of negatively charged single stranded DNA (ssDNA) due to ssDNA induced microgel crosslinking. The collapse results in a change in the etalon's optical properties, which can be used to detect target DNA in a complex mixture.     

A novel capillary electrophoretic method for determining methylglyoxal and glyoxal in urine and water samples

Two non-electroactive biomarkers methylglyoxal (MGo) and glyoxal (Go) in urine and environmental water samples were determined for the first time by capillary electrophoresis with amperometric detection (CE-AD) after derivatizing with an electroactive compound 2-thiobarbituric acid. Experimental conditions of derivatization and CE-AD detection were optimized. Highly linear response was obtained for these two biomarkers over three orders of magnitude with good correlation (r² > 0.999). The limits of detection (LODs) and limits of quantitation (LOQs) of MGo and Go were 0.2 μg L⁻¹ and 1.0 μg L⁻¹, 0.5 μg L⁻¹ and 2.0 μg L⁻¹, respectively. The average recovery and relative standard deviation (RSD) were within the range of 90.9–101.3% and 0.7–2.2%, respectively. The proposed CE-AD method provides a reliable and sensitive quantitative evaluation of MGo and Go in real sample matrices by employing relatively simple and inexpensive instrument.