1-(4-偶氮苯基苯)-3-丙基-三氮烯键合硅胶修饰碳糊电极溶出伏安法测定饲料中镉的研究

以1 - (4 - 偶氮苯基苯) - 3 - 丙基 - 三氮烯键合硅胶(ABPT - SG)为修饰剂,液体石蜡为粘合剂,制备了ABPT - SG修饰碳糊电极.在pH8.0、浓度为0.2 mol/L的氨性缓冲底液中,于-1.2 V(Vs.SCE,下同)的电位下富集,将Cd2+以Cd - ABPT - SG络合物的形式吸附在电极上,用阳极溶出伏安法测定.在-0.60 V处Cd有一灵敏的阳极溶出峰,峰电流与Cd2+的浓度在5.0×10-6～1.0×10-3 mol/L范围内呈良好的线性关系,测定饲料中的镉,检出限为1.0×10-8 mol/L.     

二氧化钛纳米管修饰电极测定食醋中镍含量

在pH 8.0的NH4Cl-NH3·H2O缓冲液中,-1.10V富集3min后,Ni 2+在阳极溶出扫描过程中会产生灵敏度高的特征溶出峰,据此建立了基于二氧化钛纳米管修饰电极线性扫描阳极溶出伏安法测定食醋中镍含量的新方法。优化了分析底液、富集电位与时间以及修饰剂用量等测定参数。在优化条件下,溶出峰电流与Ni 2+在3.0×10-7~5.0×10-5 mol/L浓度区间有较好的线性规律,检出限为1.0×10-7 mol/L(S/N=3)。运用本方法测定了食醋中的镍含量,结果满意。     

电化学还原石墨烯修饰电极测定酱油中铅含量

在玻碳电极表面电化学还原氧化石墨烯制备石墨烯修饰电极,通过优化支持电解质及pH值、修饰剂用量、富集电位及时间等测定条件,建立了基于该电极测定酱油中铅含量的线性扫描阳极溶出伏安分析法.在pH 4.5的NaAc-HAc缓冲液中,-1.10 V富集5 min后,pb2+的浓度在1.0×10-8 ～4.0×10-5 mol/L区间内与溶出峰电流呈线性,检出限为3.0×10-9 mol/L.对5.0×10-6 mol/L Pb2+溶液平行测定10次的RSD为2.6％.将该方法用于酱油中铅含量的测定,平均回收率在95.8％～104.6％之间,结果满意.     

线性扫描溶出伏安法测定豆瓣酱中镉的研究

利用石墨烯修饰玻碳电极,通过优化支持电解质及pH值、修饰剂用量、富集电位及时间等测定条件,建立了测定豆瓣酱中镉的线性扫描阳极溶出伏安分析法.在pH4.2的NaAc-HAc缓冲液中,-1.10 V富集5 min后,溶出峰电流与Cd2+浓度在1.0×10-8～5,0×10-5 mol/L范围内呈良好的线性关系,检出限为3.0×10-9 mol/L.对5.0×10-6 mol/L Cd2+溶液平行测定10次的RSD为2.8％.将该方法用于豆瓣酱中镉的测定,平均回收率在96.7％～105.0％之间,结果满意.     

1—（4—偶氮苯基苯）—3—丙基—三氮烯键含硅胶修饰碳湖电板溶出伏安法测定饲料中镉的研究

以1-(4-偶氮苯基苯)-3-丙基-三氮烯键合硅胶(ABPT-SG)为修饰剂,液体石蜡为粘合剂,制备了ABPT-SG修饰碳糊电极。在pH8.0、浓度为0.2mol/L的氨性缓冲底液中,于-1.2V(Vs.SCE,下同)的电位下富集,将Cd2+以Cd-ABPT-SG络合物的形式吸附在电极上,用阳极溶出伏安法测定。在-0.60V处Cd有一灵敏的阳极溶出峰,峰电流与Cd2+的浓度在5.0×10-6～1.0×10-3mol/L范围内呈良好的线性关系,测定饲料中的镉,检出限为1.0×10-8mol/L。     

碳纳米管修饰电极差分脉冲伏安法测定微量Pb2+

以碳纳米管(CNT)修饰玻碳电极为工作电极,于-1.0V吸附富集后差分脉冲伏安法测定水中微量铅离子,实验优化了支持电解质、pH、CNT用量。从富集电位正向扫描至0V,在-0.58V处产生铅的阳极溶出峰,溶出峰电流值与Pb2+浓度在0.005～1μg/mL范围内呈良好的线性关系,线性方程为y=16.0911x-0.2284(r=0.9962),检测下限为0.005μg/mL,回收率为95.4%～105.5%,6次重复测定RSD为1.69%。碳纳米管显著改善了铅离子检测信号,所提出的检测方法简单、灵敏、快速、选择性好,能应用于实际样品测定。     

抗坏血酸在聚对苯二酚/铜复合膜修饰电极上电催化氧化行为的探究

利用电沉积法制备了聚对苯二酚/铜(PHQ/Cu)复合膜修饰电极,并采用循坏伏安法探究了抗坏血酸(AA)在该电极上的电催化氧化行为。结果表明,与裸电极、PHQ修饰电极相比,PHQ/Cu复合膜修饰电极对AA具有更好的催化作用,表明两种修饰剂对AA的电催化氧化有良好的协同催化作用;在0.1 mol/L磷酸盐缓冲溶液(pH=4.35)中,AA的氧化峰电流与其浓度在5×10-4~1.0×10-1 mol/L范围内呈良好的线性关系,线性方程为lgI=0.7364lgc+1.6932,R2=0.9959,检出限为2.0×10-5 mol/L。该复合膜修饰电极在冰箱内贮存9 h,其电化学信号基本保持不变,且共存物几乎不干扰AA的测定,表明电极具有良好的稳定性和较强的抗干扰能力,可以用于饮料中AA含量的测定,回收率在95.5%~109.1%之间。     

基于铁基金属有机骨架电化学传感器检测食品中的Cd2+和Pb2+

制备铁基金属有机框架（Fe-HHTP）负载于多壁碳纳米管修饰玻碳电极（Fe-HHTP-MWCNT/GCE）传感器,用来同时检测食品中的Cd2+和Pb2+。经过一系列的条件优化,实验结果表明Cd2+和Pb2+在pH=5.75的醋酸盐缓冲液、富集电位为-1.0 V、富集时间为180 s、修饰涂层为3层的时候,有比较明显的效果。在优化条件下,发现Cd2+和Pb2+的溶出峰电流的变化趋势和浓度有关,并形成了良好的线性关系。Cd2+的线性范围为5～500 ng/mL,（R2=0.9993）,检出限为0.538 ng/mL;Pb2+的线性范围为5～500 ng/mL,(R2=0.9997),检出限为0.592 ng/mL。该法可用于检测粮食、饮料、生活饮用水中Cd2+和Pb2+的含量,结果较为满意。     

可再生电化学传感器同步检测贝类中痕量铅和镉

目的：针对贝类中高毒重金属铅（Pb）和镉（Cd）,开发一种可再生、廉价、快速、灵敏的电化学传感器。方法：以自制离子液体/石墨烯电极（IL/GNs HME）为工作电极,采用微分脉冲阳极溶出伏安法（DPASV）原位镀铋,根据得到的溶出峰电流,实现对Pb2+和Cd2+的同步测定。结果：在铋离子质量浓度500 μg/L,富集时间420 s,搅拌速度600 r/min,富集电压-1.1 V,缓冲体系HAc-NaAc pH 4.2的条件下,利用电化学传感器测得的Pb2+和Cd2+的线性范围均为1.0~45.0 μg/L,检测限分别达0.5 μg/L和0.8 μg/L。采用IL/GNs HME电化学传感器同时检测扇贝、褶牡蛎、长竹蛏、菲律宾蛤子中Pb2+、Cd2+含量时,所得结果均与电感耦合等离子体质谱（ICP-MS）检测结果相符。结论：基于IL/GNs HME构建的电化学传感器操作简便、灵敏度高,可实现对贝类中Pb2+、Cd2+含量的快速、同步测定。     

Pt—Fe(Ⅲ)/MWCNTs修饰电极伏安法测定食品中的亚硝酸根

采用滴涂法和电化学沉积法构建Pt—Fe(Ⅲ)/多壁碳纳米管(MWCNTs)修饰玻碳电极(Pt—Fe(Ⅲ)/MWCNTs/GCE),研究该修饰电极对NO2-的电催化作用,并优化试验条件,在该基础上建立一种差分脉冲伏安法(DPV)测定NO2-的新方法。NO2-的氧化峰电流与其浓度在3.0×10-7~2.0×10-3 mol/L范围内呈良好的线性关系(r=0.999 3),检测限为1.0×10-7 mol/L,将该方法用于食品中NO2-的测定,效果满意。     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

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.     

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.     

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.     

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.