反相HPLC法同时测定烟草中的甲酸、乙酸和乳酸

以0.01moL/L NaH2P04-H3PO4 (pH=1.20)缓冲溶液作酸化剂,丙酮为提取剂,对溴苯甲酰甲基溴为衍生化试剂,Waters C18(3.9mm×150mm,5μm)作色谱柱(柱温35℃),乙腈、甲醇和水为流动相(梯度洗脱,流速1.0mL/min),采用反相液相色谱法同时测定(检测波长255nm)了8种烟草样品中的甲酸、乙酸和乳酸.结果表明:[1]3种有机酸的回收率为97.9%～106.5%;相对标准偏差5.17%～7.33%;检测限1.32～3.30μg/mL;[2]2种卷烟样品的乙酸含量均与6种烟叶样品的差别不大,而其甲酸和乳酸含量却远远高于烟叶样品,尤其是乳酸含量约是烟叶样品的2～8倍.     

离子色谱法同时测定烟叶中的K+、Na+、Ca2+、Mg2+和NH4+

以5%盐酸为提取剂,超声提取30min,Dionex CS12A阳离子交换柱作分离柱、IonPacCG12A为保护柱,20.0mmol/L甲磺酸溶液为流动相,流速0.25mL/min,采用离子色谱法同时测定了烟叶样品中的K 、Na 、Ca2 、Mg2 和NH4 。结果表明,该法的RSD<6.22%,回收率为90.9%~109.9%,适合批量烟样中这5种离子的快速分析。     

离子色谱法测定烟用香精香料中的硝酸根和亚硝酸根

对烟用香精香料中的NO3–和NO2–采用振荡萃取,建立了快速检测烟用香精香料中的NO3–和NO2–的离子色谱法(IC)。香精香料试样中的NO3–和NO2–在振荡条件下用水、二氯甲烷萃取,经0.22 μm滤膜净化,柱流速为1.0 mL/min,采用浓度梯度洗脱方式,IonPac AS11阴离子分析柱、电导检测器检测,并采用该方法测定了15个烟用香精香料样品。结果表明:①NO3–和NO2–的检出限、回收率、相对标准偏差（RSD）及线性范围分别为0.010和0.006 μg/mL,95.4%和90.6%,3.42%和4.61%,0.06 ~ 6.0 μg/mL和 0.02 ~ 2.0 μg/mL;② 测定的15个烟用香精香料样品中NO3–的检出率53.3%,NO2–的检出率40.0%。该方法具有快速、灵敏、简便等优点,适合于烟用香精香料样品中NO3–和NO2–的测定。      

在线固相萃取-离子色谱法测定再造烟叶浆料中的17种有机酸

为测定再造烟叶浆料中有机酸的浓度,利用过滤、离心、在线固相萃取净化和浓缩样品,通过离子色谱阀切换、二元梯度泵清洗再生净化柱,高压泵分离AS11-HC离子色谱柱中的有机酸,建立了同时测定再造烟叶浆料中17种有机酸的在线净化离子色谱法。结果表明:①17种有机酸在0.5~10.0 μg/mL范围内线性关系良好,相关系数均大于0.999,方法检出限为0.002~0.400 μg/mL,定量限为0.010~0.900 μg/mL。②在2、4、6 μg/mL 3个加标水平的平均回收率为90.5%~117.1%,相对标准偏差为0.4%~4.4%。17种有机酸日内、日间测定结果的变异系数分别在0.59%~2.57%、0.72%~4.80%之间。该方法操作简便、可靠、重复性好,可用于再造烟叶浆料中有机酸的测定。      

HPLC测定不同品种石韦中绿原酸、芒果苷、咖啡酸、芦丁含量

目的用高效液相色谱法(HPLC)测定不同品种石韦中绿原酸、芒果苷、咖啡酸和芦丁含量。方法色谱柱为Venusil XBP C_(18)(L)柱(4.6 mm×150 mm,5μm),检测波长300 nm,柱温25℃,流动相为乙腈-0.2%磷酸溶液,流速1.0 mL/min,外标法定量。结果绿原酸、芒果苷、咖啡酸和芦丁分别在0.025~0.150mg/mL(r=0.9999),0.025~0.163 mg/mL(r=0.9991),0.025~0.150 mg/mL(r=0.9979),0.025~0.188 mg/mL(r=0.9986)范围内线性关系良好,不同品种石韦绿原酸、芒果苷、咖啡酸和芦丁的含量有明显差异。结论方法简便、准确,适用于石韦药材的含量测定。     

固相分散萃取-液相色谱法测定番茄酱中2-萘酚

采用固相分散萃取-高效液相色谱法测定番茄酱中的2-萘酚。无水硫酸钠作分散剂、乙腈作萃取剂,考察了2,4-二氯苯氧乙酸存在时的干扰情况。色谱条件:TOSOHC18色谱柱;甲醇-水(体积比50∶50)为流动相;流速:1.0 mL/min;检测波长:230 nm。2-萘酚在0.005μg/mL～2.00μg/mL范围内线性良好,方法检出限为1μg/g,平均回收率为75.0%,相对标准偏差为3.0%。     

超高效液相色谱法测定烟叶中的茄尼醇含量

为了更简便高效地分析烟叶中游离茄尼醇的含量,建立了一种超高效液相色谱(UPLC)快速分析方法。将烟叶样品用甲醇超声提取10 min,经膜过滤直接进行超高效液相色谱分析;在1.7μm BEH C18色谱柱上用甲醇洗脱,在5 min内实现了茄尼醇的快速分离,并用电喷雾四级杆-飞行时间质谱(Q-TOF-MS)对m/z 613.57和631.58进行了定性分析。结果表明,茄尼醇的质量浓度范围为0.765～76.5μg/mL时,峰面积与质量浓度具有良好的线性关系,相关系数为0.99924,方法的检出限7.65 ng/mL,RSD为2.62%,平均回收率为91.1%。该方法适合于烟叶中游离茄尼醇含量的快速准确测定。     

高效液相色谱法测定午时茶颗粒中厚朴酚与和厚朴酚的含量

目的建立高效液相色谱法(HPLC)测定午时茶颗粒中厚朴酚及和厚朴酚含量的方法。方法采用HPLC,色谱柱为Agilent Eclipse XDB-C_(18)柱(5μm,4.6 mm×250 mm),流动相为乙腈-水-冰醋酸(60:38:2),检测波长294 nm,柱温35℃,流速为1.0 mL/min。结果厚朴酚在1.02159~20.43184μg/mL,和厚朴酚在1.04066~20.81328μg/mL范围内线性关系良好,厚朴酚与和厚朴酚加样回收率分别为98.45%和99.37%。结论该方法简便、准确、重现性好,适于午时茶颗粒中厚朴酚与和厚朴酚的含量测定。     

高效液相色谱同时检测不同类型烟叶中的多种生物碱含量

为快捷准确地测定烟叶中生物碱的含量,本研究通过优化提取条件,建立了测定烟草中烟碱、新烟草碱、假木贼碱和降烟碱的高效液相色谱检测方法。优化后的检测步骤为：干烟叶和5%甲醇的料液比为100 mg/20 mL,在25℃下振荡提取30 min,色谱条件：C18柱（250 mm×4.6 mm,5 μm）,流动相A（90%水+10%甲醇,pH 6.8,0.15%醋酸钠）,流动相B（90%甲醇+10%水,pH 3.8）。烟碱在0.1~50 μg/mL、其余3种在0.005~2μg/mL的范围内,4种生物碱均具有较好的线性关系（R²>0.99）;烟碱检出限为0.000 65 μg/mL,平均回收率100.79%,RSD 3.11%;新烟草碱检出限0.088 4 μg/mL,平均回收率98.53%,RSD 3.75%;假木贼碱检出限0.034 8μg/mL,平均回收率98.70%,RSD 3.63%;降烟碱检出限0.150 9 μg/mL,平均回收率101.33%,RSD 4.61%。对4种不同类型烟叶共11个不同样品进行检测验证,检测结果可靠。该方法前处理简单快捷,灵敏度高,重复性较好,可以满足烟草样品中4种生物碱的检测要求。     

固相分散萃取-液相色谱法测定豆沙中的富马酸二甲酯

采用固相分散萃取技术对豆沙样品进行预处理,用高效液相色谱法测定其中的富马酸二甲酯。Diamonsil C18色谱柱,柱温25℃,甲醇-水（体积比为55∶45）作流动相,流速1.0mL/min,检测波长220nm。富马酸二甲酯在0.136μg/mL～33.5μg/mL范围内线性良好,相关系数为0.9998,方法检出限0.82μg/g,平均回收率82.5%,相对标准偏差为3.3%。市售豆沙馅中未检出富马酸二甲酯。     

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.