基于氢氧稳定同位素的桃果原汁掺水鉴别

以鲜榨桃汁为研究对象,利用全自动真空冷凝抽提技术,对桃汁样品中的水分进行无分馏提取,利用元素分析仪—稳定同位素质谱仪(EA-IRMS)对水样氢氧同位素进行同时测定,通过添加试验对分析方法可靠性进行评价,利用所建立的分析方法结合多重比较分析探讨桃汁掺不同比例水分后氢氧同位素比值的变化规律。结果表明:添加USGS45样品中δ2 H为(-11.10±1.39)‰,δ18 O为(-2.38±0.53)‰;添加GB04459样品中δ2 H为(-62.50±0.59)‰,δ18 O为(-7.95±0.41)‰;添加GB04460样品中δ2 H为(-142.00±3.40)‰,δ18 O为(-20.26±2.14)‰;与标准水样USGS45、GB04459、GB04460相比,3个样品的氢氧同位素比值均无显著性差异(P0.05),说明试验方法操作过程中未发生明显的氢氧同位素分馏效应。鲜榨桃汁中掺杂外源地下水后氢氧同位素均呈明显的重同位素贫化趋势,综合这两种指标,说明地下水占比自10%起便可实现桃汁掺水的鉴别。     

气相色谱-燃烧-稳定同位素比值质谱测定葡萄酒中甘油δ~(13)C的可行性探讨

气相色谱-燃烧-稳定同位素比值质谱技术(GC-C-IRMS)在单体化合物的稳定同位素组成分析中具有重要应用,探讨了应用该技术测定葡萄酒中甘油碳同位素比值的可行性并优化了分析条件。研究结果表明,该方法的分析精度可优于0.3‰,然而样品的理化特性,如乙醇含量和甘油含量均会影响结果的准确性。应用"相同处理"原则配制标准品可用于样品数据校正,但是由于不同葡萄酒中乙醇和甘油含量差异较大,使得标准品的配制过程很复杂。因此,我们认为GC-C-IRMS不适于葡萄酒中甘油碳同位素分析。     

GC-C-IRMS测定葡萄酒中6种风味物质的碳同位素比值

建立一种利用气相色谱-燃烧-稳定同位素比值质谱仪测定葡萄酒中的6种风味物质(乙醇、甘油、异戊醇、乳酸乙酯、乙酸、2,3丁二醇)的碳稳定同位素比值的方法。采用滤膜过滤,稀释或直接上机测定,优化测定方法,风味物质分离完全,分析时间小于20 min。6种风味物质标准溶液测量精度(standard deviation,SD)范围为0.064‰～0.227‰,样品测量精度为0.115‰～0.300‰。利用该技术分析部分葡萄酒样品,结果表明不同地域样品及不同组分间C同位素比值存在一定差异。     

基于稳定氢氧同位素技术的花生油掺假检测技术研究

建立了高温裂解/元素分析-稳定同位素比值质谱联用技术（TC/EA-IRMS）测定油脂稳定氢氧同位素比值（δ2H和δ18O）的方法,并根据氢氧同位素特征开展花生油掺假检测技术研究。对28个花生样品、5个大豆样品和6个油菜籽样品榨油后测定δ2H值和δ18O值,结果发现三种油的δ2H值分布范围分别为-231.50‰~-213.69‰、-183.11‰~-169.53‰和-192.17‰~-175.82‰;δ18O值分布范围为14.06‰~16.77‰、19.77‰~20.98‰和24.31‰~27.45‰;其中花生油的δ2H值与大豆油和菜籽油存在显著性差异（p＜0.01）,模拟实验表明根据氢氧同位素特征可检测花生油中掺入大豆油或菜籽油。通过对氢氧同位素比值的二维分布对比,可以更为全面的评价和鉴别花生油的掺杂掺假情况,为花生油的掺假鉴别提供了研究基础和技术支持。     

矿质元素与稳定同位素结合的葡萄酒产地鉴别研究

我国西北产地具有生产优质葡萄酒的能力，但仍存在风土特征不明和监管技术缺乏等问题，影响了产业发展。本研究利用电感耦合等离子质谱（ICP-MS）、液相色谱同位素质谱仪（LC-IRMS）及同位素质谱仪（EQ-IRMS）分别对新疆、河西走廊和贺兰山东麓葡萄酒样品中的24种矿质元素及3种单体稳定同位素进行测定；并利用皮尔逊（Pearson）相关性分析和单因素方差分析（one-way ANOVA）明确3个产地的指纹图谱，并结合多元分析技术评估地理起源。结果显示，在不同产地9种元素和葡萄酒中水的氧同位素具有显著性差异，各元素间相关性也显示出一定差异；葡萄酒中水的氧稳定同位素比的平均值为3.06‰，甘油碳、乙醇碳稳定同位素比的平均值分别为﹣31.78‰和﹣26.53‰。在有监督学习的逐步线性判别分析中单独使用同位素的分类正确率较低，结合元素数据，分类正确率可达95.2%，交叉验证分类结果正确率可达88.7%。综上所述，矿质元素与稳定同位素构成的多元指纹图谱是一种适合西北地区葡萄酒的有效评估方法。     

SNIF-NMR和IRMS技术在葡萄酒质量评价中的初步研究

利用SNIF-NMR和IRMS技术测定葡萄酒中稳定性同位素D/H和18O/16O的比值。结果表明,通过测定乙醇分子中甲基位(D/H)Ⅰ和次甲基位点(D/H)Ⅱ的含量,可判断葡萄酒在酿造前是否进行了加糖操作,而通过测定葡萄酒水分中18O/16O的比值,可鉴别全汁葡萄酒和半汁葡萄酒。研究结果为中国葡萄酒的质量评价提供了一种新的技术手段。     

气相色谱-质谱法测定葡萄酒中33种农药残留

本研究采用气相色谱-质谱法对葡萄酒中33种农药残留进行检测分析,考察了提取溶剂、提取方式及色谱条件对样品检测的影响。结果表明,采用丙酮/二氯甲烷超声提取结合气质联用检测技术对葡萄酒中33种农药残留进行检测,农药组分的回收率在65.2%~121.2%之间,相对标准偏差在5.9%~14.9%之间。回收率情况表明,绝大多数农药组分测试结果较好,个别项目处于可以接受的范围之内,该方法可以用于葡萄酒中33种农药的定性和定量分析。采用本方法对市场购买的47个葡萄酒样品进行检测,样品农残检出率为6.4%,检出项目有甲霜灵、嘧霉胺、氟硅唑和咪鲜胺。     

食品中高氯酸盐稳定同位素液相色谱质谱检测方法建立

建立了高氯酸盐稳定同位素液相色谱质谱的检测方法。样品加入稳定同位素内标后经提取、离心,再直接经过固定相小柱净化,过膜后直接上机测定,通过使用TorusDEA色谱中和同位素内标法优化色谱条件,解决了氯酸根和高氯酸根保留时间漂移问题,此方法简便快速,可靠性高。     

葡萄酒中乙醛气相—质谱测定方法的建立

建立气相色谱—质谱测定葡萄酒中乙醛含量的方法,并考察提取溶剂、解析pH、衍生化实际用量等因素对定量结果的影响。结果表明:该方法检测限为0.12 mg/kg,线性范围为0.2~100.0mg/kg(R~2=0.999 4),样品三水平加标回收率为89.3%~113.0%,平均相对标准偏差为1.28%~9.42%(n=6),适用于葡萄酒中乙醛总量的测定。     

气相色谱-质谱检测葡萄酒中氨基甲酸乙酯预处理方法的比较研究

目的比较液液萃取法、固相萃取法和分散式固相萃取法作为预处理方法对葡萄酒中的氨基甲酸乙酯的处理效率。方法葡萄酒样品中的氨基甲酸乙酯分别用二氯甲烷进行液液萃取,用氨基甲酸乙酯专用柱进行固相萃取,用乙腈、石墨化炭黑和N-丙基乙二胺进行分散式固相萃取,再以气相色谱-质谱联用仪测定其含量。结果 3种预处理方法的平均回收率均在70%~110%之间,相对标准偏差(n=5)均小于6%。液液萃取法处理单个样品成本小于5元,富集倍数可达5倍,可用于低含量样品的预处理和进出口企业的产品合规性检测;固相萃取法操作简便,每人每工作日可处理40个样品,可用于企业的高通量检测;分散式固相萃取法成本适中、回收率最佳、综合预处理效率高,一次预处理可同时检测葡萄酒中农药残留和氨基甲酸乙酯含量,适用于葡萄酒中多种危害物质的筛查。结论三种方法各具优势,综合考虑处理效率和实验成本,分散式固相萃取法更适合葡萄酒生产企业的日常应用。该方法已用于葡萄酒中氨基甲酸乙酯的含量测定。     

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.     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.