硫代乙醇酸修饰CdS量子点荧光猝灭法测定呋喃西林

为了对水产品中呋喃西林进行简单、灵敏分析,本论文建立了一种检测呋喃西林的荧光分析方法。以硫代乙醇酸修饰的CdS量子点(TGA-CdS QDs)为荧光探针,在pH7.0的磷酸盐缓冲溶液中,呋喃西林使TGA-CdS QDs荧光猝灭,据此建立了基于TGA-CdS QDs荧光猝灭法检测呋喃西林含量的新方法。在最佳实验条件下,检测线性范围为2.0×10-6~1.0×10-4mol/L,线性回归方程F0/F=17467 C(mol/L)+0.9918,相关系数为0.9984,检出限为7.12×10-7mol/L。方法应用于小虾呋喃西林含量的测定,回收率在95.6%~97.0%之间。     

氮硫磷氯共掺杂荧光碳点探针用于食品中胭脂红的快速检测

胭脂红（CRM）作为我国食品工业中使用最广泛的一种偶氮类色素,其致癌和致突变作用已引起人们的高度关注,建立快速、灵敏、准确的胭脂红检测方法对保障人类健康具有重要意义。该工作建立了一种基于氮硫磷氯共掺杂碳点（N,S,P,Cl-CDs）的荧光检测法用于食品中胭脂红的快速测定。以葡萄糖为碳源,乙二胺,磷酸,盐酸和硫酸作为杂原子供体,通过酸碱中和自放热法制备了蓝色荧光N,S,P,Cl-CDs。N,S,P,Cl-CDs的荧光通过静态相互作用和内滤效应（IFE）能够被CRM有效猝灭。N,S,P,Cl-CDs对胭脂红的检测展现出高选择性和高灵敏度。CRM浓度在0.01~14.0 μmol/L范围内与荧光猝灭效率F0/F呈现良好的线性关系,检测限低至9.38 nmol/L。该检测方法最终被用于食品基质中的胭脂红检测,回收率在97.8%~101.5%之间,相对标准偏差（RSDs）低于3.29%,展现出高准确性的优势。研究结果表明,该工作所建立的荧光检测方法可实际应用于食品中胭脂红的快速检测。     

荧光探针法快速检测果汁中罗丹明B残留量

建立以伊红Y为荧光探针测定罗丹明B残留量的荧光光谱法。在pH6.8的Sфrensen缓冲溶液中,一定浓度的阳离子表面活性剂溴化十六烷基三甲基铵(CTMAB)能使阴离子染料伊红Y的荧光强度显著增强,当加入一定量的罗丹明B后其荧光发生猝灭,且猝灭程度在一定范围内与加入的罗丹明B浓度呈正比。通过改变单因素,优化实验条件,获得的线性范围为0～0.9mg/L,检出限为0.0016mg/L,回收率为101.3%～113.7%,相对标准偏差为2.76%～4.98%。该方法具有简便快捷、选择性好、灵敏度高等优点,适用于果汁饮料制品中罗丹明B的检测。     

恒波长同步荧光猝灭法测定痕量亚硝酸根

在HCl介质中,Δλ=20nm,亚硝酸根对溴酸根氧化罗丹明B具有催化作用,使罗丹明B同步荧光发生猝灭,且猝灭程度与亚硝酸根浓度能形成线性关系,据此建立了恒波长同步荧光猝灭测定微量亚硝酸根的新方法。方法的检出限为1.3ng/m L,线性范围为2μg/L~52μg/L。该方法可用于火腿肠中亚硝酸根含量的测定能得到满意结果。     

氮掺杂碳量子点荧光法检测猪肉中的四环素

四环素（TC）作为一种广谱抗生素,用于预防和治疗细菌性疾病,以及作为饲料添加剂促进动物生长。本文旨在建立一种菠萝皮来源的氮掺杂碳量子点（N-CQDs）荧光猝灭法快速检测TC。以菠萝皮和二乙烯三胺为原料,通过水热法制备高量子产率的蓝色荧光N-CQDs。通过透射电子显微镜、傅里叶红外光谱、X射线光电子能谱对N-CQDs进行结构表征。结果表明,N-CQDs的平均粒径为3.53 nm,主要由C、N、O 3种元素组成,表面具有含氧和含氮基团。主要猝灭机理为静态猝灭和内滤效应。在最优试验条件下,该方法在0.3～40μg/mL范围线性良好,检出限为89.26μg/L。该检测方法被用于猪肉中四环素的检测,回收率在98.40%～106.02%之间,相对标准偏差1.29%～3.88%。     

氮掺杂碳点的开关型荧光传感器检测蔬菜中的生物硫醇

研究并建立一种开关型荧光传感器模型快速检测Hg2+和生物硫醇。以柠檬酸和尿素为前驱体,通过一锅水热法制备了氮掺杂碳点(N-CDs),并对其进行了表面形貌、紫外和荧光光谱以及表面基团表征的检测,以检测体系pH、Hg2+浓度、孵育时间(荧光猝灭和恢复时间)为单因素,优化检测生物硫醇的最佳条件,并在最优检测条件下建立相应的标准曲线。结果表明,N-CDs的最佳激发和发射峰分别是340和432 nm,量子产率(FLQY)为32.72%。优化得到谷胱甘肽(GSH)的最佳检测条件为pH=5.0,Hg2+浓度为200 μmol/L,460 s荧光猝灭和380 s荧光恢复,最佳检测半胱氨酸(Cys)条件为pH=5.6,Hg2+浓度为300 μmol/L,440 s荧光猝灭和400 s荧光恢复,在最优条件下该传感器对0~300 μmol/L的GSH和100~400 μmol/L的Cys具有线性响应,检测限(LOD)分别为2.56和3.46 μmol/L,加标回收率为80%~120%。以上结果表明该传感器对检测蔬菜中生物硫醇有较好的选择性和准确度,能为食品基质中生物硫醇的荧光快速检测提供一种新思路。     

白酒中邻苯二甲酸二(2-乙基)己酯荧光探针测定方法的构建

目的 构建一种塑化剂邻苯二甲酸二(2-乙基)己酯(di(2-ethylhexyl)phthalate,DEHP)含量测定的荧光探针检测方法。方法 基于芘分子满足激基缔合物的要求,本文选择以芘为荧光探针,设计合成了芘-聚氧乙烯蓖麻油体系(芘-EL体系)。结果 芘荧光探针在该体系中结合DEHP后収生荧光猝灭,且荧光强度的降低与DEHP的浓度之间存在线性兲系。荧光探针检测的最优条件为波长为374 nm, 400μmol/L芘-EL体系,相互作用时间30min。该方法对DEHP测定的线性范围为5～30μmol/L,线性方程为△F=-23.153+24.179C,线性相兲系数r=0.9929,检出限为0.063μmol/L,相对标准偏差为4.43%(n=6)。结论 本方法具有可视化、成本低、高灵敏度、高选择性、操作简便等优点,适用于白酒中DEHP的测定。     

新试剂4-羟基苯乙酮缩-2-氨基苯甲酸高灵敏荧光猝灭测定食品中痕量锌

合成了一种新的席夫碱荧光试剂——4-羟基苯乙酮缩-2-氨基苯甲酸。该试剂在390.4nm处有一强荧光峰,当有锌离子存在时,可与试剂形成稳定的络合物而使试剂的荧光猝灭。利用此反应建立了一个荧光测定痕量锌的新方法,测定锌的线性范围为0~130μg/L,检出限0.57μg/L,方法成功的应用于面粉、大米和矿泉水中痕量锌的测定。     

基于脱氧核酶-荧光共振能量转移效应的食品中铅离子快速检测

为实现食品中铅（Pb2+）污染的快速检测,该研究构建了一种基于Pb2+依赖型脱氧核酶（DNAzyme）及荧光共振能量转移（Fluorescence resonance energy transfer,FRET）效应的“Turn on”型铅离子检测传感器。荧光猝灭基团BHQ1可以作为FRET受体猝灭EvaGreen的荧光。当Pb2+存在时,底物链的特异性切割反应可以减弱BHQ1对EvaGreen的猝灭效果,BHQ1随底物链的断裂而释放,远离供体EvaGreen,因此FRET效应减弱,供体EvaGreen的荧光得以保留。该研究利用Pb2+诱导的FRET效应的减弱及EvaGreen荧光信号的增强可以对铅离子进行定性、定量分析。当脱氧核酶臂长为15 nt~5 nt、EvaGreen浓度为1×、底物链与酶链的浓度分别为400 nmol/L与100 nmol/L时,探究了该方法的检出限及线性范围。该反应可在室温条件下3 min内完成,同时对铅离子具有高度的特异性,可以区分不同的金属离子,并且成功应用于新鲜鸡蛋及自来水中的铅离子定量分析,加标回收率为86.79%~113.32%。该研究设计的“Turn on”型铅离子检测传感器可于室温条件下进行一管混反应,无需扩增,反应迅速,为检测食品中的铅污染提供了一些思路。     

基于荧光探针的白酒中邻苯二甲酸二丁酯(DBP)检测方法的研究

以荧光桃红作为荧光探针,设计合成了荧光桃红-十二烷基硫酸钠荧光探针体系(荧光桃红-SDS体系),构建一种塑化剂邻苯二甲酸二丁酯(Dibutyl phthalate,DBP)含量测定的荧光探针检测方法。荧光桃红荧光探针在该体系中结合邻苯二甲酸二丁酯(DBP)后发生荧光猝灭,且荧光强度的降低与DBP的浓度之间存在线性关系。结果表明,波长为468 nm,10μmol/L荧光桃红-2400μmol/L SDS体系,相互作用时间15 min,电压为800 V,搅拌时间为0 min,PBS缓冲溶液pH7,体系不人为加入乙醇,是荧光探针检测的最优条件。该方法对DBP测定的线性范围为3～30μmol/L,线性方程为:△F=4.845C+71.587,线性相关系数r=0.9983,检出限为0.214μmol/L,相对标准偏差为4.38%(n=6)。本方法成本低、灵敏度高、选择性好、操作简便,适用于白酒中塑化剂DBP的快速检测。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.