微分脉冲伏安法测定加碘盐中碘酸根离子

报道了运用微分脉冲伏安法测定食盐中碘酸根含量的方法。在1.0mol/LNaCl,pH=12的介质中,当脉冲振幅为70mV,脉冲周期为0.2s时,碘酸根离子在微分脉冲伏安图上出现一个灵敏的微分脉冲伏安峰,峰电位为-1.30V(vs.Ag/AgCl),峰电流与碘酸根离子浓度在2.0×10-7～1.0×10-5mol/L范围内成良好的线性关系,相关系数为0.9995,方法检出限为1.0×10-7mol/L。方法已用于加碘食盐中碘酸根含量的测定,平均回收率为100.7%。循环伏安(CV)测试表明,碘酸根在汞膜电极上电化学反应是不可逆过程。     

离子色谱-双波长紫外检测法同时测定水中碘酸盐和碘离子的含量

目的建立离子色谱-双波长紫外检测法同时测定水中碘酸盐和碘离子的分析方法。方法水样过0.22μm滤膜后直接进样测定,水中碘酸根和碘离子通过离子色谱柱分离,紫外检测器分别在200nm和226nm处检测。结果碘酸根和碘离子在0.01~1.00mg/L浓度范围内线性良好,相关系数r分别为0.99953和0.99950,检出限为0.004和0.005mg/L,相对标准偏差(relative standard deviations,RSDs)为2.8%和2.7%(n=8)。低(0.05mg/L)、中(0.10mg/L)、高(0.50mg/L)3个浓度IO_3~-和I~-加标回收率范围为94%~106%和92%~102%,精密度为1.04%~4.82%和0.75%~4.47%。结论本方法操作简单、准确度高、精密度好、线性范围宽,适用于水中碘酸盐和碘离子的测定。     

碘离子选择电极浓度直读法测定小麦中的碘含量

利用碘离子选择电极,在H2CO3NaHCO3为总离子强度调节剂、Na2SO3为还原保护剂、双液接饱和甘汞电极为参比电极的条件下,采用浓度直读法测定小麦中碘含量。结果表明:碘离子浓度在1.0×10-2～1.0×10-6mol/L范围内线性关系良好,该方法的回收率为95.4%～105.0%,相对标准偏差(RSD)<2%,可以用于小麦中碘含量的测定。     

甲酚红氧化褪色光度法测定海带中的微量碘

在硫酸介质中、在溴化钾催化条件下,碘酸根对甲酚红有褪色作用,且褪色的程度与碘酸根的量有关,碘定量测定的线性范围为20μg/25mL～50μg/25mL,检出限为6.57×10-1μg/25mL,回收率为98.1%～104.2%。该法重现性好、准确度高、操作简便,是测定海带中微量碘的一种较理想的方法。     

线性扫描伏安法测定食盐中碘含量

以多壁碳纳米管(MWCNT)修饰玻碳电极为工作电极,研究了碘离子在该修饰电极上的伏安分析特性,建立了测定食盐中碘含量的线性扫描伏安法。在优化实验条件下,氧化峰电流与碘离子浓度在1.0×10-6～1.0×10-3 mol/L范围内呈良好的线性关系,检出限为4.0×10-7 mol/L。对1.0×10-4 mol/L碘化钾溶液平行测定10次的RSD为3.2%。将该方法用于测定加碘食盐中的碘含量,结果满意。     

阻抑动力学分光光度法测定食品中痕量碘

研究了在稀H2SO4介质中,痕量碘离子对NO2-催化溴酸钾氧化甲基橙的阻抑作用,建立了测定痕量碘离子的阻抑动力学光度分析的新方法。测定碘离子的线性范围为0~0·6μg/mL,检出限为7·8×10-9g/mL。     

氧化褪色光度法测定食品中的碘

研究了在硫酸介质中,碘酸根在KBr催化作用下氧化罗丹明B,使其褪色的最佳条件,建立了测定微量碘的新方法。通过实验,测得最大吸收波长为490nm,表观摩尔吸光系数为1.5×104L·mol-1·cm-1,碘测定的线性范围为0～75μg/25mL,检测限为1.2×10-7mol/L。本方法的相对标准偏差为0.28%～1.9%;回收率为97.9%～101.2%。用于食品中碘的测定,结果令人满意。     

靛蓝胭脂红氧化褪色光度法测定食品中微量碘

基于稀硫酸介质中,在溴化钾的催化下,碘酸根对靛蓝胭脂红有明显的褪色作用,且褪色的程度与碘酸根的含量有关,建立氧化褪色光度法测定微量碘的方法.碘定量测定的线性范围为20 μg/25 mL～50 μg/25mL,方法的检出限为1.25×10-1 μg/mL,反应的表观摩尔吸光系数为1.354 L/(cm·mol).本法的灵敏度和选择性较高,重现性好,操作简便,用于测定海带或食盐等含微量碘较高的食品,结果满意.     

单扫描示波极谱法测定婴幼儿配方奶粉中的泛酸

提出了用单扫描示波极谱法测定婴幼儿配方奶粉中泛酸含量的新方法。基于在pH值为1.14,浓度为1.25×10-1mol/LHCl+1.20×10-2mol/LNaNO2+6.00×10-3mol/LNaAc底液中,泛酸的亚硝基衍生物于峰电位-1062mV左右出现一灵敏的极谱还原峰。泛酸的质量浓度在10～40mg/L范围内与峰电流有良好的线性关系,检出极限为1mg/L。将该法应用于测定婴幼儿配方奶粉中泛酸含量,结果令人满意,并用正交实验法确定了超声提取奶粉样品中泛酸的最佳条件。     

基于硅溶胶-凝胶化学修饰电极直接测定酱油中的曲酸

研究了曲酸在硅溶胶-凝胶化学修饰电极上的电化学行为,建立了测定酱油中曲酸的简易方法。在实验条件下,曲酸测定的线性范围为2×10-5～7×10-4mol/L,相关系数为0.9993,检测下限为1×10-5mol/L,连续测定8次1×10-4mol/L曲酸的相对标准偏差为0.9%。溶胶-凝胶化学修饰电极集分离与测定与一体,方法简单方便,可应用于酱油中曲酸含量的直接测定,避免了样品的前处理过程。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press