3,3′-二氨基联苯胺的电化学聚合及其电催化性能

运用循环伏安法在玻碳电极表面制备了３，３′－二氨基联苯胺（ＤＡＢ）聚合膜修饰电极．研究了实验条件对膜生长过程的影响和ＤＡＢ聚合膜修饰电极的电化学行为，讨论了该修饰电极对亚硝酸根和过氧化氢的电催化还原作用．结果表明：亚硝酸根和过氧化氢在ＤＡＢ聚合膜修饰电极上具有很好的电流响应，催化峰电流与底物浓度分别在１×１０－５ｍｏｌ／Ｌ～４×１０－３ｍｏｌ／Ｌ和３．０×１０－３ｍｏｌ／Ｌ～１．９×１０－１ｍｏｌ／Ｌ的范围内呈良好的线性关系，有望用于实际样品的分析．     

电流法快速测定鲜奶中蛋白质含量

采用电流法快速测定了鲜奶中蛋白质含量,该方法是利用Ｃｌａｒｋ氧电极监测在戊二醛与鲜奶中蛋白质或氨基酸的氨基反应中所消耗的氧来间接测定蛋白质含量。该方法快速、准确、便利,样品不同需要前处理。标准曲线线性范围为２．０＊１０＾－３－５．５＊１０＾－２ｍｏｌ／Ｌ。变异系数为５．７％。用本法与经典的凯氏定氮法对照测定市售３种鲜牛奶中蛋白质含量,对结果进行统计分析,得出Ｐ〉０．０１,说明两种方法无性区别。该方     

快速测定食盐中微量碘的新方法

对用亚铁盐作还原剂还原含碘盐中ＫＩＯ３进行了研究，提出了测定食盐中微量碘的新方法，使含有０．１～０．５ｍｏｌ／Ｌ的亚铁盐的酸性淀粉溶液与含碘盐作用产生蓝色吸附配合物，以示食盐中碘的存在，再根据反应显色时间的长短和颜色的深浅作用初步的定理分析，该法灵敏度高，可检测至１０＾－８ｇ，显色时间短，定性检测一个样品只需１～２ｓ，定量检测最长时间也在１０ｓ以内，且稳定性高。     

Zn—KSCN—次甲基兰—OP—PVA的吸光光度法研究和应用

研究在混合表面活性剂ＯＰ－ＰＮＡ存在下，Ｚｎ－ＫＳＣＮ一次甲基兰显色体系水相光度法测定微量锌的新方法。该缔事物最大吸收波长为５５０ｎｍ，表现摩尔吸光系数∑５５０＝１．９１×１０＾５．Ｌ．．ｃｍ＾－１．ｃｍ＾－１．ｍｏｌ＾－１，锌含量在０－８μｇ／２５ｍｌ内遵守Ｂｅｅｒ定律，方法灵敏度高，选择性好，操作方便，用该法直接测定食品中的微量锌获得满意结果。     

磁性载体对菠萝蛋白酶吸附分离和固定化的研究

以聚乙二醇为分散剂和稳定剂,用氧化低价铁盐的方法制成具有磁响应性的微球,用１．３３％浓度的该磁性微球吸附分离菠萝皮汁中的蛋白酶,回收率达６１．９６％,酶活性３．８×１０￣４ｕ／ｇ。固定化后成为具有磁响应性的磁性菠萝蛋白酶,回收方便。固定化的最佳条件为：戊二醛浓度０．１９％,ＰＨ４．３,温度２５°Ｃ。最适反应温度６０°Ｃ,最适ｐＨ值８．８～９．７,往碱性偏移,酪蛋白底物的ｋ＿ｍ值为１．１×１０＿－５ｍｏｌ／Ｌ,比游离酶的８．Ｉ×１０＿－５ｍｏｌ／Ｌ大。固定化磁性菠萝蛋白酶的热稳定性有显著的提高,常温下的半衰期为２８天左右。等电聚焦电泳图谱表明,菠萝皮计中有６种同工酶组份,均可被磁性微球团载,固定化后６种酶组份的等电点保持不变。     

条斑紫菜中四个多糖组分的提取及组成分析

利用离子交换柱层析和凝胶柱层析法对条斑紫菜热水提取物中的多糖进行了分离纯化,共获得四个不同的多糖组分,柱层析法测定它们的分子量分别为２．２＊１０＾５、２．０＊１０＾４、１．８＊１０＾５和１．５＊１０＾４。采用气相色谱及化学分析等方法测出多糖各种组成成分的含量。     

L—半胱氨酸盐酸盐的电解合成

以铅为阴极，ＤＳＡ为阳极，由Ｌ－胱氨酸电解合成Ｌ－半胱氨酸盐酸盐，阴极液为０．６６ｍｏｌ／１Ｌ－胱氨酸溶液，阳极液为２．５ｍｏｌ／Ｌ硝酸溶液，隔膜为苯乙烯磺酸膜，电流密度为７Ａ／ｄｍ＾２，电解时间为７ｈ，产率９８％电流效率为７０％。     

葡萄糖的化学发光检测法及对发酵过程糖耗曲线的测定

本文首次将葡萄糖和Ｃｕ~（２＋）的氧化反应与Ｃｕ~（２＋）催化下鲁米诺和Ｈ_２Ｏ_２的化学发光反应偶联，建立了葡萄糖的化学发光（ＣｈｅｍｉｌｕｍｉｎｅｓｃｅｎｃｅＣＬ）检测法，并成功地测定了酒精酵母发酵过程中的糖耗曲线。该方法操作简便，线性范围宽（１０~（－６）～１０~（－３）ｍｏｌ／Ｌ）。Ｆ－检验结果表明，ＣＬ法的测量精度明显高于传统的２，５－二硝基水扬酸比色法（ＤＮＳ法）。ＣＬ法的变异系数和最低检测限分别为２．６％和２．３×１０~（－６）ｍｏｌ／１（０．２ｍｌ，８３ｎｇ），均大大小于ＤＮＳ法的变异系数（５．０％）和最低检测限（１．１１×１０~（－５）ｍｏｌ／Ｌ，３ｍｌ，６μｇ）。     

Cu（Ⅱ）—甲基橙—CTMAB多元配合物显色反应的研究和应用

在非离子表面活性剂ＰＶＡ－ＯＰ存在下，铜（Ⅱ）与甲基橙和溴化十六烷基三安在水相中形成稳定的多元配合物显色体系，该配合物在５２０ｎｍ处有最大吸收峰，其摩尔吸光系数∑５２０＝８．６×１０＾４Ｌ．ｃｍ＾－１．ｍｏｌ＾－１。。铜含量在０－９μｇ／２５ｍｌ范围内服从Ｂｅｅｒ定律，用地测定莲子、麦片、豆奶等食品中的微量铜，结果满意。     

固定化增殖酵母酒精发酵新技术研究：第四报 薯类原料固定化增殖…

在前文基础上，利用Ｖ＝１１ｍ＾３传统发酵罐改造为并流型固定床反应器，进行木薯干原料固定化增殖酵母酒精发酵工业性试验。糖化醪糖化率Ｙｓ≥５０％，载体填充率８０Ｌ．ｇｅｌ／ｍ＾３反应器，发酵时间Ｔ１６．５ｈｒ，成熟醪乙醇浓度９．２２％，总糖利用率Ｕｗ＝９２．７％，糖醇化系数ＹＥ／ＳＰ＝０．４７１７，反应器容积乙醇产率ＰＶ＝４．５ｋｇ，Ｅｔ－ＰＨ／ｍ＾３．ｈｒ载体乙醇产率Ｐｃ＝５８．１８ｋｇＥｔ－ＯＨ／     

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.     

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.     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.