荧光光度法测定白果中游离氨基酸含量

采用邻苯二甲醛(OPA)衍生法，OPA在β-巯基乙醇(β—MCE)存在下与游离氨基酸迅速反应生成1-硫代-2-烷基异吲哚，此加成物具有荧光，从而利用荧光光度法测定市售白果中的游离氨基酸总量。实验对该法的精密度、稳定性以及准确性均进行探讨。在激发波长EX为330nm、发射波长EM为470nm荧光条件下，标准直线方程为Y=0．9950X 0．2063、相关系数7=0．9999，回收率达99．10％。结果表明：白果中含丰富的游离氨基酸，其总量达0．8—1．0g／100g。     

茶叶中游离氨基酸含量的荧光光度法测定

本文采用邻苯二甲醛(OPA)衍生法，OPA在β-巯基乙醇(β—MCK)存在下与第一级氨基酸迅速反应生成1—硫代—2—烷基异吲哚，此生成物具有荧光，从而利用荧光光度法测定茶叶中的游离氨基酸含量。实验对该法的精密度，准确性以及稳定性均进行探讨。在激发波长Ex为360nm，发射波长Em为420nm时，标准直线方程为Y＝1．3303X 0．2329，相关系数γ＝0．9999。结果表明：茶叶中含有丰富的游离氨基酸，总量为2．7—3.2g／100g，回收率达99．14％。     

邻苯二甲醛荧光衍生化法测定食用海藻中还原型谷胱甘肽

用质谱和光谱测定方法研究了OPA和还原型谷胱甘肽(GSH)荧光衍生化反应,发现OPA分子苯环上相邻醛基的歧化反应,使得其与GSH发生衍生化反应时生成三环和二环结构的两种衍生化产物,其中三环结构的衍生化产物具有较强的荧光发射特性。利用OPA荧光衍生化法分别测定了马尾藻、鹿角菜、龙须菜中GSH的含量。在含OPA的PBS缓冲溶液、激发波长λex=350nm时,样品溶液在428nm处发射灵敏的荧光,检测限达3.6×10-8mol/L。用标准加入法分别测定样品中GSH含量分别为:0.0714mg/g(马尾藻),0.1183mg/g(鹿角菜),0.1970mg/g(龙须菜),方法的回收率达到99.22%～100.41%。     

荧光素钠法测定β-葡聚糖含量研究

该试验通过研究荧光素钠与β-葡聚糖、葡萄糖、乳糖、麦芽糖等结合后荧光最大激发和发射波长发生变化,探索在有多种糖存在溶液中鉴别测定β-葡聚糖含量一种方法。结果显示,荧光素钠与β-葡聚糖混合前后紫外吸收分别为436．5 nm和510．6 mn,荧光素钠与β-葡聚糖结合后荧光最大激发和发射波长发生变化,激发和发射波长分别由487．3 nm,517．6 nm变为475．9 nm和510．6 nm,而与其它糖类,如葡萄糖、乳糖、麦芽糖等结合后荧光性质不发生变化,荧光素钠与β-葡聚糖结合适合比例为6:1(百分含量比)、线性浓度范围在0．1～0．25μg／mL,回归方程为y=-2．014x+1．0757,回归系数为R2=0．9978,用此工作曲线测定青稞粗品中β-葡聚糖粗提物纯度为95％(标准酶法测定结果为96％)。     

荧光素钠法测定β-葡聚糖含量的研究

通过研究荧光素钠与β-葡聚糖、葡萄糖、乳糖、麦芽糖等结合后荧光最大激发和发射波长发生的变化，探索在有多种糖存在的溶液中鉴别测定β-葡聚糖含量的一种方法，结果显示，荧光素钠与β-葡聚糖混合前后的紫外吸收分别为436．5nm和510．6nm，荧光素钠与β-葡聚糖结合后荧光最大激发和发射波长发生的变化，激发和发射波长分别由487．3nm，517．6nm变为475．9nm和510．6nm，而与其他糖类如葡萄糖、果糖、麦芽糖等结合后荧光性质不发生变化，荧光素钠与β-葡聚糖结合适合比例为6：1（百分含量比）、线性浓度范围在0．1μg／mL～0．25μg／mL，回归方程为Y=-2．014x＋1．0757，回归系数为R^2=0．9978，用此工作曲线测定青稞粗品中β-葡聚糖粗提物的纯度为95％（标准酶法测定结果为96％）。     

山黧豆中β-ODAP及其他氨基酸的提取和HPLC分析

利用氯甲酸对硝基卞酯(PNZ-Cl)作为柱前衍生化试剂,建立了山黧豆中神经毒素β-N-草酰基-L-α,β-二氨基丙酸(β-N-oxalyl-α,β-diaminopropionic,β-ODAP)及其他游离氨基酸的同时分析法。HPLC法为色谱柱Ultimate XB-C18,流动相乙腈和乙酸-乙酸钠缓冲溶液(p H值=4.6),梯度洗脱程序0~5 minφ(乙腈)25%,5~30 minφ(乙腈)25%~90%,流速0.8 m L/min,柱温30℃,检测波长300 nm。利用该方法对山黧豆中β-ODAP及其他游离氨基酸的提取条件中乙醇体积分数、山黧豆粉的质量浓度(ρ(山黧豆粉))、提取温度等进行了优化。结果表明,在φ(乙醇)为10%,ρ(山黧豆粉)为0.025 g/m L,提取温度为60℃时,提取效率较高。     

Mo(Ⅵ)-HMPF-CTMAB光度法测定食品中微量钼

研究了三元配合物Mo(Ⅵ)-2-羟基-3-甲氧基苯基荧光酮(HMPF)-CTMAB的显色条件.最大吸收波长λmax=525.00nm,试剂最大吸收波长为λmax=465.00nm,对比度60nm,ε525=1.30×105L·moL-1·cm-1,钼的浓度0～15μg/25mL,服从比尔定律,该体系选择性好、方法简便、快速,用于食品中微量钼的测定,结果令人满意.     

反相高效液相色谱法测定荔枝果实游离氨基酸

本文以邻苯二甲醛(OPA)与9-芴基羰酰氯(FMOC-CI)作衍生剂,正缬氨酸为内标,利用二极管阵列(DAD)可变波长检测程序,采用柱前衍生RP-HPLC法测定了4个荔枝品种果实的全谱游离氨基酸。结果表明:各种氨基酸的保留时间(Rt)RSD为0.01%～3.02%、相对峰面积(Ax/AI)RSD为1.19%～7.82%,回收率为92.21%～114.24%;荔枝果实中以丙氨酸(Ala)、谷氨酸(Glu)、精氨酸(Arg)、天冬氨酸(Asp)和苯丙氨酸(Phe)为主要氨基酸,其总量超过游离氨基酸总量的60%,4个荔枝品种的总游离氨基酸含量从大到小排序为:淮枝、糯米糍、黑叶、桂味。     

高效液相色谱法测定发芽米胚芽中的γ-氨基丁酸

建立一种高灵敏度的邻苯二甲醛(OPA)柱前衍生荧光检测高效液相色谱法测定发芽米胚芽中γ-氨基丁酸(GA-BA)含量的方法。色谱柱为Shimadzu VP-ODS C18柱(250mm×4.6mm,5μm),流动相:0.05mol/L乙酸钠∶甲醇=60∶40,荧光发射波长λex 338nm,激发波长λem430nm。方法的线性范围为0.10～1.0μg/mL,检出限为0.005μg/mL。日间和日内测定的精密度分别为1.36%和2.54%,加标回收率在98.5%～99.8%。该法简便、快速、灵敏度高,可用于发芽米胚芽中GABA的质量控制。     

柱前在线衍生-反相高效液相色谱法测定羊胎盘

目的：建立一种采用反相高效液相色谱法测定羊胎盘枸杞胶囊中16种氨基酸的含量。方法：样品中的蛋白质在6mol/L盐酸溶液中水解为氨基酸,其中一级氨基酸用邻苯二甲醛(OPA)、二级氨基酸用9-芴甲基氯甲酸酯(FMOC)进行柱前在线衍生;用Agilent Hypersil AA-ODS柱(200mm×2.1mm,5μm)分离;用流动相(0.16%醋酸钠)进行梯度洗脱;经荧光检测器(FLD)检测(激发波长：340nm,发射波长：450nm;15min时,激发波长：266nm,发射波长：305nm)。结果：16种氨基酸在5pmol/ul～250pmol/ul浓度范围内呈现良好的线性关系(r:0.99959～1.00000)(n=5),平均加标回收率(n=9)为91.6%～104.1%,相对标准偏差(RSD)为0.9%～3.7%,最低检测限为0.4pmol～1.2pmol。结论：该方法灵敏度高,具有良好的精密度与准确度,可以有效地控制产品质量。     

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