电荷检测在废纸浆造纸中的应用研究

用PCD(颗粒电荷测定仪)测定聚合物的电荷密度、浆料溶胶物质的阳离子需求量,用Zeta电位仪测定浆料的Zeta电位,并将这两种方法相结合探讨了浆料电荷特性及其影响因素.结果表明:PCD可以简单、快速,准确地测定聚合物的电荷密度;浆浓对阳离子需求有影响,PH值、离子浓度和填料都会影响旧瓦楞纸(Old CorrugatedContainers)浆料体系的电荷特性.     

造纸法再造烟叶浆料的湿部化学特性

运用电荷检测的方法研究了浆浓、亚麻浆配比、填料添加量、硫酸铝用量以及阳离子瓜尔胶用量对再造烟叶浆料体系的湿部电荷特性的影响。结果表明:1%浆浓的再造烟叶浆料体系的阳离子需求量、Zeta电位和电导率分别为:0.1534mmol/L、-8.5mV、0.267mS/cm。浆料体系的阳离子需求量随浆浓的增大而增加,随亚麻浆配比的增加而减少;由于再造烟叶浆料体系呈碱性,硫酸铝对其湿部电荷特性的影响有限;而阳离子瓜尔胶能够显著降低再造烟叶浆料体系的阳离子需求量,瓜尔胶用量为0.4%时,能使浆料体系的阳离子需求量降低42.5%。     

工艺因素对硫酸盐浆Zeta电位及阳离子需求量的影响

本实验探讨了多种硫酸盐浆,如未漂浆、漂白浆及打浆至不同打浆度的浆料的Zeta电位和阳离子需求量。当浆料经过漂白最后阶段的木素脱除和溶解过程,如碱抽提或次氯酸盐漂白．所测得Zeta电位要低于未漂浆。漂白后的浆料阳离子需求量要低于未漂浆。而浆料经打浆后阳离子需求量要低于未打浆浆料,原因在于打浆会使浆料组分的比表面积增大。由于打浆可增加纤维的电负性,因此浆料的阳离子需求量伴随着打浆而增加。通过对不同打浆度浆料的Zeta电位测试发现,聚胺的用量与所测得的Zeta电位之间存在线性关系。但随打浆度的增加,直线的斜率逐渐减小。     

电导率和取代度对阳离子淀粉增强作用的影响

自行合成不同取代度的季铵型阳离子淀粉,用氯化钠调节浆料的电导率,探讨不同浆料电导率和阳离子取代度对系统Zeta电位、纸张的环压强度和耐破指数的影响.结果表明,阳离子淀粉的取代度越高,系统的Zeta电位变化越大,纸张环压指数和耐破指数提高幅度越大;电导率对添加低取代度阳离子淀粉的系统Zeta电位影响较大,对添加高取代度阳离子淀粉的Zeta电位影响较小,在取代度相同的情况下,电导率对纸张环压指数和耐破指数的影响不明显.     

造纸法再造烟叶纸机湿部环境初探

利用Zeta电位仪和PCD颗粒电荷测定仪,对造纸法再造烟叶的浆料流送系统及湿部的Zeta电位和阴离子垃圾含量进行检测。结果表明,在一个生产周期内,流浆箱内浆料的Zeta电位平均值为-7.06 mV,阳离子需求量平均值高达970μmol/L,浆料中阴离子垃圾主要来自浓白水。     

造纸法烟草薄片浆料的湿部电荷特性研究

研究烟草纤维的形态,并对烟草浆的湿部电荷特性进行研究。结果表明:烟草浆中纤维含量较少,短纤维的含量也不高,烟末和杂细胞含量较高。随着pH值的提高,烟草浆中溶胶物质的阳离子需求量随之增大,pH值由4.8升高到10.0时,阳离子需求量由0.07meq·L-1升高到0.28meq·L-1,增加了300%,但Zeta电位则由-5mV降低到-9.9mV,降低了70%;随着离子浓度、浆浓和打浆度的增加,烟草浆中溶胶物质的阳离子需求量和Zeta电位都随之增加。     

造纸法再造烟叶浆料湿部化学状态分析

利用Zeta电位仪、PCD颗粒电荷测定仪、动态滤水仪、纤维形态分析仪等对再造烟叶浆料进行检测分析,结果表明:磨浆后浆料中的Zeta电位值为-14.6 m V,加入瓜尔胶后变为-13.2m V,整饰盘磨浆的阳离子需求量为-93ueq/L,白水中的阳离子需求量为-270ueq/L,加入瓜尔胶后的上网浆阳离子需求量变为-207ueq/L,反而降低,但滤水留着实验及灰分测试表明瓜尔胶的加入会提高浆料的滤水性和留着率。上网浆阳离子需求量增大主要是白水中细小纤维含量高导致的。上网浆料中细小纤维(面积比)高达27.64%。     

不同化学品对细菌纤维素配抄针叶木浆性能的影响

研究细菌纤维素配抄针叶木浆后添加不同化学品对浆料pH值、电导率、Zeta电位、阳离子需求量等电化学性质和成纸物理强度的影响。结果表明,细菌纤维素表面呈强负电性,在加了细菌纤维素的针叶木浆料系统中加入一定量的硫酸铝或CPAM,可以调节其电化学性能,使成纸物理强度增加更为明显。     

湿部化学检测方法分析纤维吸附能力的研究

本文利用Zeta电位仪和颗粒电荷检测仪,通过检测不同目数的浆料在添加阳离子试剂前后浆料Zeta电位和浆料过滤水颗粒电荷的变化情况,分析纤维对阳离子试剂的吸附能力。实验发现,颗粒电荷检测仪能够较好的判断试剂在水介质中的溶解情况;但是Zeta电位不能真实反映纤维对阳离子试剂的吸附能力,其主要原因一方面是由于纤维会发生表面吸附和内部吸附,内部吸附部分无法通过Zeta电位仪检测;另一方面是由于不同浆浓条件下可电离基团的电离平衡常数不同,并且不同的纤维形态Zata电位和颗粒电荷会相互干扰。     

电荷测量技术用于阳离子淀粉对脱墨浆助留的研究

应用Zeta电位和CTR(胶体滴定比率)分析脱墨(旧报纸)浆料体系的电荷分布情况。研究了不同阳离子淀粉用量、pH值、电导率对浆料Zeta电位、CTR和单程留着率的影响。研究表明,浆料的Zeta电位和CTR可以说明实际电荷分布情况且与阳离子淀粉对浆料的助留作用密切相关。     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the