促进龙胆紫褪色光度法测定饲料中牛磺酸含量

根据牛磺酸具有促进高碘酸钾氧化龙胆紫褪色的原理,考察酸度、高碘酸钾用量、龙胆紫用量、温度和时间对反应的影响,建立分光光度法测定饲料中牛磺酸的新方法。结果表明:最佳反应条件为在10 ml比色管中加入pH1.99盐酸 乙酸钠缓冲溶液1.0 ml、2.5×10-3 mol/L高碘酸钾溶液1.0 ml和2.5×10-4 mol/L龙胆紫溶液1.0 ml,室温下反应11 min。在波长570 nm处,吸光度减小值与牛磺酸质量浓度在0~0.25 μg/ml范围内呈良好的线性关系,表观摩尔吸光系数为3.88×105L/（mol·cm）,检出限为1.91 μg/L;结合超声波提取和离子交换法预分离技术,采用牛磺酸促进高碘酸钾氧化龙胆紫褪色光度法测定饲料中牛磺酸含量,结果与高效液相色谱法一致,标准偏差为0.82%~1.29%(n=5),回收率为98.6%~101.9%。     

抑制氧化酸性品红光度法测定蚝油中牛磺酸含量

研究了牛磺酸对高锰酸钾氧化酸性品红反应的抑制作用,建立了分光光度法测定牛磺酸的新方法。结果表明:最大褪色波长为590nm,线性范围为0~125μg/L,表观摩尔吸光系数为4.51×105 L/mol·cm,检出限为4.2μg/L。方法用于测定蚝油中牛磺酸含量,结果与高效液相色谱法一致,标准偏差为1.85%~2.17%(n=6),回收率为99.2%~101.8%。     

促进龙胆紫褪色光度法测定饲料中牛磺酸含量

根据牛磺酸具有促进高碘酸钾氧化龙胆紫褪色的原理,考察酸度、高碘酸钾用量、龙胆紫用量、温度和时间对反应的影响,建立分光光度法测定饲料中牛磺酸的新方法.结果表明:最佳反应条件为在10 ml比色管中加入pH1.99盐酸-乙酸钠缓冲溶液1.0 ml、2.5×10-3 mol/L高碘酸钾溶液1.0 ml和2.5×10-4 mol/L龙胆紫溶液1.0ml,室温下反应11 min.在波长570 nm处,吸光度减小值与牛磺酸质量浓度在0～0.25 μg/ml范围内呈良好的线性关系,表观摩尔吸光系数为3.88×105 L/(mol·cm),检出限为1.91 μg/L;结合超声波提取和离子交换法预分离技术,采用牛磺酸促进高碘酸钾氧化龙胆紫褪色光度法测定饲料中牛磺酸含量,结果与高效液相色谱法一致,标准偏差为0.82％～1.29％(n=5),回收率为98.6％～101.9％.     

抑制氧化甲基橙光度法测定贝类中牛磺酸

本研究建立了分光光度法测定贝类中牛磺酸的新方法。痕量牛磺酸在pH 11.0氨-氯化铵缓冲液中对高锰酸钾氧化甲基橙的反应具有显著抑制作用,使体系褪色,吸光度明显减小。试验了酸度、高锰酸钾用量、甲基橙用量、温度和时间的影响,确定了最佳反应条件。在最佳反应条件下,最大褪色波长位于690 nm,吸光度减小值与牛磺酸质量浓度在0~75μg/L范围内呈良好的线性关系,表观摩尔吸光系数为2.22×106 L/(mol·cm),检出限为1.19μg/L。采用热水浸提和离子交换法处理样品,将该方法用于测定文蛤、缢蛏、栉孔扇贝和四角蛤蜊中牛磺酸,结果与高效液相色谱法一致,相对标准偏差为0.82~1.24%(n=6),回收率为98.31~101.76%。该方法灵敏、准确、简便、快速、精密度高,选择性好,反应条件温和,对环境友好,适用于贝类中牛磺酸的测定。     

健那绿B褪色光度法测定啤酒酵母中铬含量

采用微波消解样品,碱性条件下用高锰酸钾氧化铬(Ⅲ)为铬(Ⅵ),铬(Ⅵ)在磷酸介质中与碘化钾和健那绿B反应,使健那绿B褪色,据此建立褪色光度法测定铬含量的新方法。结果表明:最大褪色波长为618 nm,吸光度减小值与铬(Ⅵ)质量浓度在0~0.24μg/mL范围内呈线性关系,检出限为2.95μg/L。新建方法用于测定啤酒酵母中铬含量,结果与原子吸收光谱法一致,相对标准偏差为0.86%~1.29%(n=5),样品加标回收率为98.7%~101.0%。     

动力学光度法测定啤酒中痕量甲醛

建立了动力学催化光度法测定痕量甲醛的新方法。在磷酸介质中,痕量甲醛对KBrO3-氨基黑10B体系的褪色反应具有强烈催化作用,以此指示反应探索出测定痕量甲醛的最佳试验条件,并研究了该指示反应的动力学参数。方法的线性范围在0～0.12mg/mL,检出限为1.23×10-8g/mL。     

流动注射褪色光度法测定水样中的亚硝酸盐

在酸性环境中,双氧水和偏钒酸铵反应可生成有色的过氧钒酸盐,而亚硝酸盐可使有色的过氧钒酸盐褪色,褪色产物的检测波长为470 nm,据此建立了流动注射褪色光度法测定亚硝酸盐的新方法。该方法简单、快速、选择性好。现对影响该方法的显色体系和流路体系进行了优化。在优化的实验条件下,当亚硝酸盐(NO_(2)^(-)-N)浓度在50~2500μg/L时,浓度与峰高呈良好的线性;检出限为4.5μg/L;重复测量结果之间的相对标准偏差为0.64%(1000μg/L亚硝酸盐,n=13)。利用本法分析不同水样中的亚硝酸盐,回收率在97.9%~101.1%之间,测定结果与国标法一致。     

亮绿褪色光度法测定酵母中钴含量

研究钴(Ⅱ)与硫氰酸钾和亮绿的络合反应,建立褪色光度法测定钴含量的新方法。通过试验优化酸度、硫氰酸钾用量、亮绿用量、反应温度和反应时间等测定条件。结果表明:最大褪色波长为624nm,表观摩尔吸光系数为2.2×105 L/mol·cm,钴(Ⅱ)浓度在0~0.30μg/mL范围内服从比尔定律,检出限为2.5μg/L。方法用于测定酵母中钴含量,结果与原子吸收光谱法一致,相对标准偏差为0.53%~0.81%(n=5),回收率为98.1%~101.5%。     

阻抑动力学光度法测定纺织品中痕量壬基酚

在硫酸介质和Fe3+催化剂条件下,壬基酚能灵敏地阻抑过氧化氢氧化氨基黑褪色,因而可将其用于测定纺织品中痕量壬基酚.壬基酚阻抑褪色反应的最佳条件:氨基黑溶液0.4 mL,H2SO4溶液0.4 mL,H2O2用量0.25 mL,Fe3+溶液0.25 mL,反应温度为90 ℃,反应时间为9 min.在0~8 mg/L范围内,ΔA与壬基酚的浓度呈良好的线性关系,线性方程ΔA=0.006 6 C-0.001 4,该方法检出限为4.45×10-4 mg/L.用于纺织品中壬基酚的测定,其回收率为89.2%～96.5%,相对标准偏差为1.2%～6.70%.     

超高效液相色谱-串联质谱法测定饲料中9种氨基糖苷类抗生素

目的 建立超高效液相色谱-串联质谱法测定饲料中9种氨基糖苷类抗生素(aminoglycosides, AGs)的分析方法。方法 样品采用10 mmol/L磷酸二氢钾缓冲液作为提取液, 酶探针超声提取1 min, 通过阳离子交换固相萃取柱净化, 在电喷雾电离正离子模式下使用超高效液相色谱-串联质谱仪进行检测, 外标法定量。 结果 经方法学验证, 在5~1000 μg/L范围内, 9种AGs均呈现良好的线性关系, 方法的检出限为5~20 μg/kg, 定量限为20~80 μg/kg。在20~400 μg/kg添加浓度范围内, 饲料中9种AGs的平均回收率为76.2%~113.2%; 日内变异系数为1.1%~8.4%, 日间变异系数为1.1%~11.6%。结论 该方法稳定、灵敏, 可同时实现饲料中9种AGs的检测, 满足饲料中AGs日常监测应用需求。     

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