罗丹明B光谱探针测定面粉中过氧化苯甲酰

研究在磷酸氢二钠- 磷酸二氢钾缓冲溶液中(pH 6. 84),以罗丹明B 为光谱探针,分光光度法测定面粉中过氧化苯甲酰(BPO)的方法。结果表明,室温下,罗丹明B-BPO 体系在550nm 波长处有最大吸收,表观摩尔吸光系数(ε)为 1.1 × 104 L/mol·cm。BPO 含量在0.00～0.80mg/ml 范围内符合朗伯比尔定律。检出限为0.056mg/kg,加标回收率为97.5%～101.0% ,RSD 为1.46%～2.53%。该法简便易行,适用于基层单位测定面粉中微量BPO。     

碘化钾-吖啶红体系光度法测定小麦面粉中的过氧化苯甲酰

采用碘化钾-吖啶红分光光度法对小麦面粉中过氧化苯甲酰含量进行了测定。在硫酸介质中,有聚乙烯醇存在的情况下,过氧化苯甲酰氧化I-生成I3-,I3-与吖啶红发生离子缔合反应,导致KI-吖啶红-聚乙烯醇溶液体系的吸光度下降,在525 nm波长下,过氧化苯甲酰在0.04～6.0 mg/L内与吸光度的改变量呈线性关系,据此建立了测定小麦面粉中过氧化苯甲酰的碘化钾-吖啶红分光光度法,该法用于小麦面粉中过氧化苯甲酰的测定,平均回收率为98.2%与101.6%。     

血色素催化鲁米诺化学发光法检测过氧化苯甲酰的研究

过氧化苯甲酰(BPO)作为一种面粉改良剂,可在短时间内提高面粉白度,但是过量添加会严重危害到消费者健康.结合过氧化苯甲酰可直接氧化鲁米诺产生化学发光的特点,在催化剂血色素的作用下,利用流动注射-化学发光分析仪进行高灵敏度检测,建立了通过化学发光测定面粉中过氧化苯甲酰的新方法.其检测的线性范围在5×10-9 mol/L～5×10-7 mol/L,工作曲线回归方程为y = 2.215×108x + 2.401×108 (r = 0.9992),检出限为6×10-11 mol/L.对浓度为1.0×10-8mol/L的BPO平行测定20次,相对标准偏差为2.1%.该方法无需繁杂的样品预处理过程,简便、快捷、准确可靠,其灵敏度大大超过了高效液相色谱中的紫外检测,可作为一种检测手段应用于市场上面粉质量的安全控制.     

基于罗丹明B探针的鲜柠檬中柠檬酸的快速测定

建立了快速测定鲜柠檬中柠檬酸的可见分光光度法。研究结果证明:在弱碱性的Tris-盐酸缓冲介质中,柠檬酸与罗丹明B反应,在可见光区生成具有2个明显负吸收峰的离子缔合物,最大负吸收波长位于580 nm,次大负吸收波长位于494 nm。用双波长法测定,柠檬酸的质量浓度在0.03～1.92 mg/L范围内服从比尔定律,表观摩尔吸光系数(κ)为2.20×10~4 L/(mol·cm),检出限为0.009 0 mg/L,定量限为0.056 g/100 g。该方法用于鲜柠檬中柠檬酸的测定,结果令人满意。     

甲基绿吸收光谱法同时测定饮料中的酒石黄和日落黄

研究建立了一种简便、快速、能同时测定饮料中共存着色剂——酒石黄和日落黄的吸收光谱新方法。在pH 9.43 Tris-HCl溶液中,甲基绿与酒石黄和日落黄发生显色反应,生成离子缔合物,在400~750 nm范围内,酒石黄体系在574 nm波长处产生1个能进行定量分析的特征负吸收峰,共存色素日落黄不干扰测定,酒石黄的质量浓度在0.04~16.0 mg/L范围内与缔合物的吸光度绝对值(A)有很好的线性关系,表观摩尔吸光系数为4.90×10⁴ L/(mol·cm),检出限为0.033 mg/L,饮料的定量限为1.80 mg/kg;日落黄体系在488 nm波长处产生1个能用于定量分析的特征正吸收峰,共存色素酒石黄不干扰测定,日落黄的质量浓度在0.04~13.6 mg/L范围内与缔合物的吸光度有很好的线性关系,表观摩尔吸光系数为4.19×10⁴ L/(mol·cm),检出限为0.028 mg/L,饮料的定量限为1.51 mg/kg。该方法简便、快速,通过控制溶液酸度便可在不经分离的情况下同时测定同一饮料样品中共存色素——酒石黄和日落黄的含量。     

IO_3~-I~--罗丹明6G体系双峰双波长光度法测定食盐中碘含量

在硫酸介质中,有聚乙烯醇存在下,IO-3氧化I-生成I-3,再与罗丹明6G形成离子缔合物,该缔合物在495nm和560nm波长存在最大负吸收和最大正吸收,碘酸根的浓度在一定范围内与吸光度呈线性关系,据此建立了测定痕量碘酸根的IO-3-I-罗丹明6G体系双峰双波长分光光度法,方法用于含碘食盐中碘酸根的测定,结果令人满意。     

I_3~-—罗丹明类染色体系测定食盐中碘

在HCl介质中,KIO3与过量的KI反应生成I3-,I3-继而分别与罗丹明6G(Rh6G),罗丹明B(RhB)和丁基罗丹明B(b-RhB)形成离子缔合物,从而使各体系的吸光度明显降低,且3种体系的最大吸收峰分别位于526,558和559 nm处。KIO3浓度分别在0.04~0.80μg/mL范围内与吸光度变化值ΔA之间基本符合比耳定律,其表观摩尔吸光系数分别为1.77×105,1.87×105和2.06×105L.mol-1.cm-1。此方法可用于直接测定食盐中的碘。     

小麦粉中过氧化苯甲酰的定性和定量检测方法研究

基于过氧化苯甲酰(BPO)在酸性加热条件下可氧化Fe2+生成Fe3+,Fe3+与二安替比林甲烷(DAPM)形成橙色络合物而显色的原理,建立了小麦粉中BPO快速定性分析的目视比色法和定量分析的分光光度法。研究了缓冲液用量、硫酸亚铁铵用量、DAPM用量、反应温度和反应时间对显色的影响,并对实验条件进行了优化。结果表明,在最优化实验条件下,显色体系的颜色随BPO浓度的升高而加深,色度值呈规律性变化,且在BPO浓度0 mg/L~12 mg/L范围内符合比尔定律,线性回归方程为ΔA=0.036+0.110 C(mg/L),R2=0.9996,420 nm处表观摩尔吸光系数ε=2.765×104 L/(mol·cm)。该法用于实际样品的分析,目视比色法可快速确定BPO的含量范围,分光光度法检出限为0.016 mg/L,加标回收率为97.0~101.8%,相对标准偏差(RSD)小于5%。     

高效液相色谱法同时测定小麦粉中过氧化苯甲酰和苯甲酸及其含量稳定性考察

目的建立高效液相色谱法同时测定小麦粉中过氧化苯甲酰(benzoyl peroxide,BPO)和苯甲酸(benzoyl acid,BA)的方法并进行过氧化苯甲酰稳定性考察。方法直接提取样品中过氧化苯甲酰和苯甲酸并用高效液相色谱法直接同时测定,考察在不同基质类型、浓度水平、不同阶段中过氧化苯甲酰在样品储存过程中的动态变化与稳定性。结果相对标准偏差(relative standard deviation;RSD)10%,在工作液浓度范围0.05(苯甲酸为0.10μg/m L)～100.00μg/m L具有良好的线性关系(r~20.999),空白基质加标量1 mg/kg时苯甲酸、过氧化苯甲酰回收率分别为91.2%、100.4%,其他加标量苯甲酸回收率范围99.1%～109.9%;在阴性基质加标水平分别为20、10、5 mg/kg时,30 d后BPO直接测定含量的总体降低比率分别为33.4%、16.3%、8.1%,呈不断降低趋势。结论新方法可更准确地掌握过氧化苯甲酰在样品和前处理与检测过程的转化情况,可得到更可靠的评判数据,避免现有检测方法定性和定量不确切的缺陷。     

Cu~(2+)-钨酸盐-罗丹明6G体系共振散射光谱法测定面粉和茶叶中微量铜

利用Cu2+和钨酸盐形成的铜钨杂多酸阴离子与罗丹明6G阳离子结合生成离子缔合物的反应,建立一种测定Cu2+的共振散射光谱法。该反应在聚乙烯醇存在条件下,于589 nm波长处产生的共振散射光强度与Cu2+质量浓度在0.05~1.0 ng/m L范围内有良好的线性关系,线性回归方程为ΔI=4.38+77.12c(r=0.997 1),方法的仪器检出限为0.026 ng/m L。方法简单、快速、灵敏度高,且大量存在的常见离子对Cu2+的测定不干扰,将其用于面粉和茶叶样品中铜的测定,相对标准偏差在3.5%以内,回收率在96.7%~104.1%之间。     

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