Al3+荧光增敏快速检测酸奶和乳酸菌饮料中的胭脂虫红酸（英文）

研究溶剂、浓度、pH值以及金属离子对胭脂虫红酸荧光性能的影响,表明胭脂虫红酸在pH 4且其物质的量浓度为2.0×10^-4 mol/L的水溶液中荧光最强;而胭脂虫红酸对金属离子选择性识别的结果显示,Al^3+能使胭脂虫红酸的荧光强度显著增强从而提高检测的灵敏度。以Al^3+(2.0×10^-3 mol/L)为标准溶液检测样品中胭脂虫红酸含量时,胭脂虫红酸的物质的量浓度在1.0×10^-5~8.0×10^-5 mol/L范围内与其荧光强度呈良好的线性关系,检测限为5.0×10^-6 mol/L。实际应用结果表明,用荧光法检测不同酸奶和乳酸菌饮料中添加的胭脂虫红酸的含量,样品回收率在96.6%~110.5%之间,相对标准偏差小于5.9%。本研究为快速、有效、定量地检测食品中的胭脂虫红酸提供了一种有效的方法。     

紫胶色酸A的荧光性质及其在检测中的应用

考察紫胶色酸A的荧光性质和影响因素,探索其对金属离子的识别作用以及在实际检测中的应用。结果表明,溶剂的化学特性和极性、其自身浓度以及溶液的pH值都会影响紫胶色酸A的荧光强度和发射波长;Cu2＋、Fe3＋、Fe2＋和Pb2＋使紫胶色酸A的荧光猝灭,而Zn2＋和Al3＋使其荧光增强,其中Al3＋体现出显著增强紫胶色酸A荧光强度的特异性,其他金属离子对其荧光强度几乎没有影响。在Al3＋（0.04?mol/L）存在的条件下,紫胶色酸A的荧光强度与其浓度呈良好的线性关系。应用实验结果表明,以Al3＋为标准液,用荧光法检测两种不同饮料中添加的紫胶色酸A的含量,样品回收率在95.0%～109.3%之间,相对标准偏差在1.9%～5.4%之间。本实验开发了一种新的检测紫胶色酸A的方法,该方法具有实际应用价值。     

高效液相色谱法测定食品中胭脂虫红的含量

本文建立了食品中胭脂虫红的高效液相色谱检测方法。样品用磷酸水提取,经微孔滤膜过滤,采用C_(18)色谱柱分离,在乙腈-0.5%H_3PO_4溶液流动相下分离,检测波长为275 nm。结果表明:胭脂虫红在0.5~50 mg/kg范围内,具有较好的线性关系;方法定量限为0.1 mg/kg;加标回收率为89.3%~98.8%,相对标准偏差为1.58%~3.12%。该方法简便、准确度高,适于食品中胭脂虫红含量的测定。     

固相萃取-高效液相色谱法测定食品中痕量花粉红染料

本实验建立了测定食品中痕量花粉红色素的高效液相色谱方法.样品经正己烷等溶液提取,经过中性氧化铝柱净化,以甲醇和水溶液为流动相进行色谱分离,在激发波长550 nm,发射波长580 nm的荧光条件下检测.花粉红的浓度在0.5～10.0 μg/ L 范围内与其色谱峰面积的线性关系良好( r=0.999),在1、5、10 μg/kg添加水平时的回收率为56.3 %～80.1%,RSD为2.8 %～5.7%.方法的定量检出限为1.0 μg/kg.     

胭脂虫中洋红酸的C18-HPLC-PDA检测

目的:建立一种对胭脂虫中的洋红酸进行定性、定量分析的C18-HPLC方法,对我国四川西昌地区产胭脂虫中的洋红酸含量进行初步评估。方法:(1)用pH=9的0.0125 mol/L的Na2CO3溶液萃取洋红酸;(2)最终HPLC分离条件:固定相:SUPERIDREX ODS C18色谱柱(39 mm×15 cm,4μm);流动相A:甲醇-水(2:8v,/v),用磷酸调pH为5;流动相B:甲醇;线性梯度洗脱:B在15 min内由0增至100%;流速:0.8 mL/min;PDA波长收集范围为250～630 nm;色谱图检测波长:533 nm;进样量:20 mL。(3)用外标法测定样品中洋红酸的含量。结果:我国西昌地区产胭脂虫中洋红酸的含量为307.02 mg/g。     

UPLC-MSMS法快速检测食品中胭脂虫红酸含量的研究

文章建立了食品中胭脂虫红酸含量的超高效液相色谱-串联四极杆质谱（UPLC-MSMS）检测方法。样品采用盐酸溶液在沸水浴下提取,在酸性条件下用聚酰胺固相萃取小柱富集、净化,氨水/甲醇溶液洗脱后注入超高效液相色谱仪,由BEHC18柱（1.7μm,2.1×100mm）快速分离后进入串联四极杆质谱仪检测。本方法胭脂虫红酸检测限为0.1mg/kg。5种食品样品回收率为85.9%～109.2%,相对标准偏差（RSD）为1.7%～5.1%（n=6）,在0.2μg/mL～10μg/mL浓度范围内呈良好的线性关系,线性回归系数r=0.9985。     

一种快速检测Hg2＋的比率荧光传感器构建

以汞离子（Hg2＋）为检测对象，构建一种基于（silicon-doped carbon quantum dots，Si-CDs）-溶菌酶（lysozyme，Lys）功能化的金纳米簇的比率型荧光传感器。以发蓝色荧光的Si-CDs为参比荧光信号，发红色荧光的Lys功能化金纳米簇（Lys-AuNCs）为响应荧光信号构建比率荧光探针。基于Au＋-Hg2＋间的亲金效应，Hg2＋可高效猝灭Lys-AuNCs在670 nm波长处的荧光发射，而Si-CDs在470 nm波长处的荧光强度保持不变，其荧光强度比值（I670/I470）与Hg2＋（0～0.016 mg/L）呈良好的线性关系，线性方程为I670/I470=1.35－64.18C（Hg2＋）。对湖水、矿泉水、自来水3 个水样进行添加回收实验，其回收率均在94.3%～115.0%之间，检出限为0.001 mg/L（3σ），变异系数不大于10.3%，且并无其他金属离子干扰。     

尿素对经动态高压微射流(DHPM)诱导去折叠胰蛋白酶构象变化的影响

以牛胰蛋白酶为原料,通过紫外吸收光谱、荧光发射光谱和圆二色谱研究尿素对天然胰蛋白酶和经动态高压微射流(DHPM)诱导去折叠胰蛋白酶的构象变化。结果显示：天然胰蛋白酶构象在尿素浓度4.0～6.0mol/L之间变化最显著,紫外吸光度从0.2746降至0.1824,吸收峰从波长279nm红移至283nm,相对荧光强度从105.9降至98.27,发射峰从波长352nm红移至355nm,β-折叠含量从46.9%降至30.6%;而去折叠胰蛋白酶构象在尿素浓度2.0～4.0mol/L之间变化最显著,紫外吸光度从0.3121降至0.2159,吸收峰从波长281nm红移至283nm,相对荧光强度从108.24降至99.07,发射峰从波长353nm红移至360nm,β-折叠含量从40.6%降至38.9%。表明尿素对经DHPM处理后处于部分去折叠胰蛋白酶构象的影响更为显著。不同浓度尿素导致胰蛋白酶产生不同构象的中间体,表现出“熔球态”模型特征。     

同步荧光法结合主成分分析法鉴别橙汁品质

对鲜榨橙汁与市售某品牌橙汁进行同步荧光扫描得到其三维荧光光谱,并从光谱中提取出3 组特征峰。然后结合其中荧光物质的特性,得知这3 组特征峰对应物质分别为VB2、VB6和黄酮类物质。同时,采用主成分分析法结合于激发波长240～640 nm、发射波长与激发波长差为30 nm条件下扫描而得的同步荧光光谱数据对所有橙汁样品进行聚类并识别,效果良好。结果表明：将荧光光谱技术与光谱模式识别方法相结合,可为橙汁品质鉴别提供有力技术支持。     

壳聚糖-活性红4缔合体系的荧光猝灭与共振瑞利散射光谱分析及其在壳聚糖定量分析中的应用

在弱酸性Britton-Robinson缓冲体系中,壳聚糖对活性红4存在荧光猝灭作用,在激发波长（λEx）/发射波长（λEm）=285 nm/341 nm处,在0.050～2.00 μg/mL质量浓度范围内,其荧光猝灭程度与壳聚糖质量浓度呈良好的线性关系。线性方程为ΔF=68.78c＋2.648（c,μg/mL）,R2=0.999 2,检出限为0.039 μg/mL。在相同的介质环境中,壳聚糖-活性红4离子缔合体系于波长342 nm处产生强烈的共振瑞利散射特征峰,共振瑞利散射强度与壳聚糖质量浓度c呈良好线性关系,在0.050～6.00 μg/mL质量浓度范围内,线性方程为：ΔI=681.31c＋114.95（c,μg/mL）,R2=0.999 1,检测限为0.033 μg/mL。据此,建立以活性红4为探针定量分析壳聚糖的2 种新方法：荧光猝灭法和共振瑞利散射法。同时,将2 种方法就壳聚糖分子质量对测定结果准确性的影响进行研究。将2 种新方法应用于实际样品的定量检测,测定结果基本一致,且回收率结果令人满意。     

HPLC-DAD-FLD同时测定柑橘果汁中12种多甲氧基黄酮和香豆素类物质

建立高效液相色谱-串联二极管阵列检测器和荧光检测器(high performance liquid chromatography-diode array detector-fluorescence detector,HPLC-DAD-FLD)同时检测柑橘果汁中12种多甲氧基黄酮、香豆素及呋喃香豆素类物质的方法。以0.01%磷酸、甲醇、乙腈组成三元流动相进行梯度洗脱,12种物质在30 min内实现基线分离。利用DAD和FLD获得各物质的紫外和荧光光谱信息,将柑橘果汁样品组分的光谱与之比对,并结合色谱保留时间,实现样品成分的定性分析。分别以320 nm和450 nm为紫外和荧光的检测波长,研究该方法的定量性能。结果显示:标准曲线线性关系良好;荧光定量限低至μg/L级,可作为紫外定量的重要补充手段;果汁回收率的紫外和荧光检测值分别为95.2%~104.8%和94.5%~103.5%。该方法对样品定性、定量分析准确,适合柑橘多甲氧基黄酮、香豆素等能发射荧光物质的检测。     

高效毛细管电泳法测定胭脂虫提取物中胭脂红酸

建立高效毛细管电泳法(HPCE)测定胭脂虫提取物中胭脂红酸含量的方法以含5% 乙腈、5% 乙二醇的40mmol/LNa2HPO4-Na2B4O7·10H2O 混合缓冲液(pH9.434)为背景电解质,60cm × 75μm 未涂层毛细管柱为分离泳道,分离电压20kV,0.5psi × 10s 压力进样,柱温25℃,检测波长239nm,此条件下,采用峰面积内标法定量;在选定的电泳条件下,胭脂红酸质量浓度在50～500mg/L 范围内线性关系良好,线性相关系数R=0.9958,加标回收率为100.86%,方法检出限(RSN=3)为5.00μg/mL。本方法测定胭脂红酸含量试剂用量少,简便、快速、准确,可应用于实际生产中胭脂红酸的测定。     

诺邓火腿红色素的分离纯化及结构鉴定

为探究诺邓火腿红色素化学本质,采用75%丙酮溶液提取,结合C₁₈固相萃取小柱进行分离纯化,通过紫外-可见光光谱(ultraviolet spectroscopy,UV-Vis)、荧光光谱、超高效液相色谱-串联质谱(ultra-high performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)、傅里叶变换红外光谱(Fourier transform infrared,FTIR)和核磁共振(nuclear magnetic resonance,NMR)共同表征诺邓火腿红色素的化学结构。结果表明：在UV-Vis中416 nm处有1个强吸收峰,546 nm和584 nm处有2个弱对称吸收峰,符合金属卟啉特征;以420 nm激发,红色素在590 nm处有1个强荧光发射峰,644 nm处有1个弱荧光发射峰,与Zn-原卟啉IX(Zn protoporphyrin IX,ZnPP)标准品比对后高度重合,表明卟啉环中的金属离子是锌离子;在UPLC-MS/MS的正离子(m/z 625.177 9[M+...     

Application of synchronous fluorescence spectroscopy with multivariate data analysis for determination of butter adulteration

The potential of fluorescence spectroscopy for detection of butter adulteration with palm and coconut oils was investigated. Synchronous fluorescence spectra were collected in the range of 240–700 nm with wavelength intervals (?λ) of 10, 30, 60 and 80 nm. The applied technique was used to detect the addition of palm and coconut oils to butter, and the lowest limit of detection for adulteration (LOD – 5.5%) was observed after applying the wavelength interval of 60 nm. The multiple linear regression (MLR) models were used to calculate the level of adulteration with the lowest root mean square error of calibration (RMSEC) and root mean square error of validation (RMSEV) of 3.8 and 3.9%, respectively, for the measurements acquired at the wavelength interval of 60 nm.     

三聚氰胺树脂为氮源的氮掺杂碳量子点制备及光学性能

以三羟甲基三聚氰胺树脂为氮源,乙二胺、对苯二胺和1,8-二氨基萘为碳源,采用一步水热法制备了三种氮掺杂碳量子点(N-CQDs-1、N-CQDs-2和N-CQDs-3),探究了三种氮掺杂碳量子点的结构及光学性能.结果表明,N-CQDs-1、N-CQDs-2和N-CQDs-3的平均粒径分别为3.87、7.09和2.79 n...     

Photochemical behaviour of hydrolysed keratin

An investigation into the influence of UV irradiation on keratin hydrolysates was carried out using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. It was found that the absorption of keratin hydrolysates in solution increased during irradiation of the sample, most notably between 250-280 and 320-410 nm. The increase in absorbance in the region 320-410 was because of the new photoproducts formed during UV irradiation of keratin hydrolysates. The fluorescence of keratin hydrolysates was observed at 328 nm after excitation at 270 nm. UV irradiation caused fluorescence fading at 328 nm, and after 60 min of irradiation, a new broad weak band of fluorescence, attributable to new photoproducts, emerged in the UV wavelength region with emission maximum between 400 and 500 nm. FTIR spectroscopy results showed degradation of keratin under UV irradiation. A slight increase in oxidized sulphur species was also observed. The results obtained suggest that UV irradiation can be used as modifying agent for preparation of keratin hydrolysates for cosmetic applications.     

Hyperspectral fluorescence imaging using violet LEDs as excitation sources for fecal matter contaminate identification on spinach leaves

Food safety in the production of fresh produce for human consumption is a worldwide issue and needs to be addressed to decrease foodborne illnesses and resulting costs. Hyperspectral fluorescence imaging coupled with multivariate image analysis techniques for detection of fecal contaminates on spinach leaves (Spinacia oleracea) was evaluated. Violet fluorescence excitation was provided at 405 nm and light emission was recorded from 464 to 800 nm. Partial least square discriminant analysis and wavelength ratio methods were compared for detection accuracy for fecal contamination. Fluorescence emission profiles of spinach leaves were monitored over a 27 days storage period; peak emission blue-shifts were observed over the storage period accompanying a color change from green to green–yellow–brown hue. The PLSDA model developed correctly detected fecal contamination on 100 % of relatively fresh green spinach leaves used in this investigation, which also had soil contamination. The PLSDA model had 19 % false positives for non-fresh post storage leaves. A wavelength ratio technique using four wavebands (680, 688, 703 and 723 nm) was successful in identifying 100 % of fecal contaminates on both fresh and non-fresh leaves. An on-line fluorescence imaging inspection system for fecal contaminant detection has potential to allow fresh produce producers to reduce foodborne illnesses and prevent against the associated economic losses.     

Characterization of fatty acid profile by FFFS

The purpose of the study was to assess potential application of front face fluorescence spectroscopy as a rapid and non-destructive technique to discriminate between fats of animal and plant origin based on their fatty acid profiles, and to predict concentration of fatty acids from fluorescence spectra. Vitamin E emission spectra (300–500 nm) of butterfat and vegetable oil samples were recorded with excitation wavelength set at 295 nm. Fatty acid composition of the samples was determined by gas chromatography. Principal component analysis and partial least squares regression analysis were applied to the gas chromatography and fluorescence spectroscopy data. The butter-fats and vegetable oils were discriminated based on the total saturated and unsaturated fatty acids respectively. Tocopherols and tocotrienols accounted for the variability among various oils. A good prediction model was established with R ² = 0.745–0.992 for saturated fatty acids. The unsaturated fatty acids were characterized by low coefficients of determination (R ² < 0.339). The fatty acid profiles predicted from fluorescence spectra did not show significant difference to those determined by gas chromatography used as references. A good association was established between the two data tables. The study demonstrated great potential of front face fluorescence spectroscopy to rapidly discriminate between fats of animal and plant origin, and predict their saturated fatty acids composition, which could in turn be used for detection of milk fat adulteration with vegetable oil.     

蛋白饮料中胭脂红酸的高效液相色谱-荧光法检测技术研究

建立了高效液相色谱．荧光法定量检测蛋白饮料中胭脂红酸的方法。样品经过8mol／LNFLOH溶液处理5min,过滤后直接进高校液相色谱。色谱条件：流动相：乙腈和1．19mol／L的甲酸（19：81,v／v）;流速0．8mL／min,进样量：20此,荧光检测的激发波长hx=470nm,发射波长hm=600nm。该方法条件下,胭脂红酸在浓度5斗g,mL-80μg/mL线性关系良好,检测限为0．1mg／kg,相对标准偏差（RSD）小于4．25％,加标回收率为90．34％-95．15％。该方法在多种人工合成红色素的存在的条件下,可以实现对胭脂红酸进行准确的定量检测。