微波消解-石墨炉原子吸收法测定香辛料中铅含量

对呼和浩特大型超市以及农贸市场采购的家庭常用香辛料7个品种28个样品进行了重金属铅的含量测定。采用石墨炉原子吸收分光光度法测定铅含量,在微波消解法的基础上添加了预消解。结果经过预消解-微波消解,原子吸收分光光度法测定,计算出八角的回收率范围为97.2%~99.3%,桂皮的回收率范围为99.7%~99.9%,花椒粉的回收率范围为99.9%~100.2%;经过微波消解,原子吸收分光光度法测定,计算出八角的回收率范围为95.0%~96.5%,桂皮的回收率范围为99.5%~99.7%,花椒粉的回收率范围为99.4%~99.8%。预消解-微波消解法比微波消解法具有消化的完全、彻底,回收率高等优点。     

复配膨松剂中铝元素含量测定的研究

目的:建立微波消解-石墨炉原子吸收分光光度法测定复配膨松剂中铝元素含量的方法。方法:样品经硝酸-过氧化氢溶液微波消解后,采用石墨炉原子吸收分光光度测定复配膨松剂中铝元素的含量。结果:该方法线性良好,相关系数为0.998;铝元素的检出限为0.24 mg/kg;回收率在85.5%~97.7%之间;相对标准偏差≤3.8%(n=6)。结论:该方法操作简单、灵敏度高、检出限低,满足复配膨松剂中铝元素含量的测定。     

石墨炉原子吸收法测定稻谷中铅含量前处理方法比较

研究采用石墨炉原子吸收法测定稻谷中铅含量的几种不同前处理方法,分别采用压力消解罐消解、微波消解、干法灰化和湿法消解四种前处理方法提取同一稻谷样品中的铅.用石墨炉原子吸收法测定,以磷酸二氢铵和硝酸镁混合溶液作为基体改进剂,铅标准溶液浓度范围为5、10、20、40、50 ng/mL,相关系数=0.999 9.压力消解罐消解、微波消解、干法灰化和湿法消解四种前处理方法测定结果的回收率分别为97.6％、82.3％、82.9％和87.1％.结果表明,四种前处理方法各有优缺点,均可用于稻谷中铅含量的测定.     

微波消解-石墨炉原子吸收法测定香精香料中的砷、铅

为采用石墨炉原子吸收分光光度法准确测定香精香料中的砷、铅含量,考察了8种前处理方式和5种基体改进剂对测定的影响.结果表明:①微波消解是香精香料中砷、铅测定的适宜前处理方式;②磷酸二氢铵-硝酸镁和氯化钯-硝酸镁分别为铅、砷测定的适宜基体改进剂;③该方法砷、铅的相对标准偏差≤5%,回收率在95.0%～104.0%之间,砷、铅的检测限各为0.32μg/L和0.13μg/L.该方法适合香精香料中痕量砷、铅的定量分析.     

微波消解-石墨炉原子吸收法测定保健食品软胶囊壳中铬含量

目的:建立石墨炉原子吸收分光光度法测定保健食品软胶囊壳中铬含量的方法。方法:采用微波消解仪对样品进行消解,以石墨炉型原子吸收分光光度计对其铬含量进行测定。结果:铬在0-40ng/m L范围内线性关系良好,相关系数为0.9992,最低检出限为0.2ng/m L,回收率均在90-105%之间。结论:该方法简便、快捷,具有较高灵敏度、准确度、精密度和较低的检出限,适用于保健食品软胶囊壳中铬含量的测定。     

不同消解方法-石墨炉原子吸收法测定食品污染物中铅、镉含量的对比研究

目的:以不同消解方法,测定食品污染物中铅、镉含量的对比。方法:样品分别采用湿法消解和微波消解两种前处理法,以石墨炉原子吸收分光光度计对食品污染物中铅、镉含量进行测定,比较不同消解方法的精密度、重复性及回收率等。结果:湿法消解和微波消解法的铅浓度在0.0～50.00μg/L、镉浓度在0.0～5.000μg/L均具有良好的线性关系,相关系数均 0.999;平均回收率均在95.5%～100.8%;两种方法的相对标准偏差RSD均在3.5%以内。结论:两者比较中,微波消解法进行样品前处理更简便、更快捷、更环保、更节省、更适于食品污染物中铅和镉含量测定。     

固相萃取柱脱盐-石墨炉原子吸收法测定酱油中铅

目的 建立固相萃取柱脱盐—石墨炉原子吸收法测定酱油中铅的方法.方法 酱油经微波消解后,消解液用乙酸铵调节至pH≈5.5,过经用5 ml 1 mol/L乙酸铵活化后的DigiSEP-Blue柱,将被测元素铅吸附与基体中高盐分离,再分别用8 ml 2 mol/L硝酸、2 ml纯水洗脱,应用石墨炉原子吸收法测定洗脱液中铅含量.结果 用固相萃取柱可将酱油中98％以上的钠盐与被测元素铅分离,消除了石墨炉原子吸收分光光度计测定铅时的基体干扰.低、高两个铅浓度(10和30 ng/ml)的加标平均回收率(n=7)分别为91.3％ ～95.1％,97.9％～98.6％,相对标准偏差为2.1％ ～7.0％,检出限为1.33 ng/g.结论方法准确、灵敏度高,适于高盐样品酱油中铅含量的测定.     

微波消解-原子吸收分光光度法测定保健食品中铝元素含量

目的建立微波消解-石墨炉原子吸收分光光度法测定固体、液体和软胶囊3种基质的保健食品中铝元素含量的分析方法。方法前处理方法经实验确定为5 mL硝酸和2 mL过氧化氢(30%,V:V)双溶剂消解,经微波消解仪消解,采用石墨炉原子吸收分光光度测定保健食品中铝元素的含量。结果铝元素在0～500μg/mL的浓度范围内线性关系良好,相关系数为0.998;铝元素的检出限为0.24 mg/kg;回收率为81.2%～98.7%;相对标准偏差小于3.2%(n=6)。结论该方法操作简单、灵敏度高、检出限低,满足保健食品中铝元素含量的测定。     

沸石中微量元素含量的测定——火焰原子吸收分光光度法

采用火焰原子吸收分光光度法测定沸石中微量元素的含量。通过湿法消解沸石,采取火焰原子吸收分光光度法测定K、Na、Ca、Mg、Fe的含量。产生了各元素加标回收率是98.47%-102.45%,是满足要求的即结果准确方法适用。证明火焰原子吸收分光光度法测定沸石中微量元素是可行的。     

乳及乳制品中重金属铅的检测技术

铅是重金属污染中毒性较大的一种,一旦进入人体很难排除.当铅长期蓄积于人体时,会严重危害神经、造血系统及消化系统,对婴儿的智力和身体发育影响尤其严重.已被列为食品卫生监督的重要元素.测定铅常见的方法有分光光度法、原子吸收法和电化学分析法等,其中传统的分光光度法灵敏度不够,若用火焰原子吸收,含量低时不能准确进行测定,为此,用石墨炉原子吸收分光光度法测定乳与乳制品中的铅,通过一系列实验选出了测定的最佳实验条件,并将检测方法过程中的各个环节的影响因素进行了剖析.     

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.     

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.     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

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.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.