微波消解-电感耦合等离子体质谱法测定卡拉胶中的砷、铅、镉、汞含量

采用微波消解-电感耦合等离子体质谱法测定卡拉胶中的砷、铅、镉、汞含量,在试验条件下,砷、铅、镉标准曲线在0～50.0μg.L^-1浓度范围内线性相关系数为0.9998～0.9999,检出限为0.3～0.5μg.kg^-1;汞标准曲线在0～10.0μg.L^-1浓度范围内线性相关系数0.9999,检出限0.3μg.kg^-1;卡拉胶样品中砷、铅、镉、汞加标回收率为91.0%～110%。实验表明,该方法操作简单、灵敏度高、精密度高、检出限低、省时省力,适用于卡拉胶中的砷、铅、镉、汞含量测定     

比较微波消解-原子荧光法和电感耦合等离子体质谱法测定饲料中总砷

目的对比微波消解-原子荧光法和电感耦合等离子体质谱法测定饲料中总砷含量。方法采用微波消解作为样品前处理手段,原子荧光法和电感耦合等离子体质谱法作为检测方法,采用标准物质对两种方法进行验证。结果微波消解-原子荧光法检出限为0.006 mg/kg,线性相关系数为0.9998,相对标准偏差为6.3%和3.2%;微波消解-电感耦合等离子体质谱法检出限为0.003 mg/kg,线性相关系数为0.9999,相对标准偏差为2.4%和2.6%。2种方法对标准物质的测定结果均在标准值允许范围内。结论2种方法均操作简便快速,具有较低的检出限、较高的准确度和精密度,其中原子荧光法适合批量样品分析,电感耦合等离子体质谱法适用于总砷含量较高的样品。     

微波消解-电感耦合等离子体质谱法测定油茶籽和核桃中的8种金属元素

建立了微波消解-电感耦合等离子体质谱法测定油茶籽和核桃中的铅、镉、铬、砷、汞、铜、锌、铁8种金属元素的方法.试验优化了微波消解条件和仪器测定条件,方法检出限为0.31 ～31.6μg/kg,加标回收率在80％ ～ 110％之间,RSD在1.7％～7.8％(n=6)之间.采用该方法对黄豆标准样品(GBW10013)和苹果标准样品(GBW10019)进行验证,测定值均在标准值范围内.采用该方法测定了不同地区的油茶籽和核桃中的金属元素含量,其中有害金属元素含量远低于现行标准的限量值.对于油脂含量较高样品中多金属元素的测定,该方法具有准确、快速、低检出限的特点.     

食品中铝含量国标测定法的改进

目的通过优化微波消解试剂和微波消解条件,解决国标推荐方法对生物样品消解不彻底的问题,使其能够准确测定食品中铝含量。方法采用国标推荐的微波消解方法和优化后的微波消解方法迚行样品的前处理,消解河南小麦、芹菜、猪肝、大虾和粉丝粉条等标准参考物质,采用电感耦合等离子体发射光谱法测定铝含量。结果采用国标推荐的微波消解前处理方法,试样测定结果进低于参考值。采用优化的微波消解程序(硝酸-氢氟酸体系),标准参考物质的铝含量测定结果较为接近标准参考值。铝含量在0～10.0μg/mL范围内线性关系良好(r=0.9998),标准参考物质中铝含量的回收率为71.9%～110%,相对标准偏差为1.3%～6.3%。结论硝酸-氢氟酸体系与优化的微波消解程序方法能将样品消解更为彻底,使检测结果更加准确,该法可用于食品中铝含量的测定。     

微波消解-电感耦合等离子发射光谱测定鸡肉中9种元素

建立微波消解-电感耦合等离子发射光谱测定鸡肉中Ca、Fe、Zn、Se、Ni、Mn、Cu、Pb、As九种元素的方法。测定结果表明,此方法的检出限为0.0004～0.0069mg/L,相对标准偏差(n=3)为0.72%～4.10%,回收率为80.0%～107.1%。同时研究微波消解试剂的种类和加入量、微波消解升温程序对测定结果的影响;并且将微波消解与干灰化法、湿法消解进行比较,结果显示,经微波消解后,测得多种元素的值显著性高于干法灰化、湿法消解(P＜0.05)。     

微波消解-电感耦合等离子体质谱法测定话梅中的铅

目的 建立微波消解-电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry, ICP-MS)测定话梅中铅的分析方法。方法 话梅样品用硝酸-过氧化氢经微波消解仪消解, 定容后用电感耦合等离子体质谱仪测定, 用185Re内标校正铅含量, 并转换成样品中的铅含量。结果 铅含量在0~50 μg/L线性关系良好, 线性相关系数r=1.0000, 检出限为0.0314 mg/kg。在精密度实验中, 其相对标准偏差为0.35%~2.15%, 在1.0 mg/kg的添加水平下, 加标回收率为94.42%~102.36%。结论 该方法线性关系好, 检出限低, 稳定性好, 回收率高, 测定结果准确, 适合话梅中铅的测定。     

高通量密闭微波消解-ICP-MS测定食品中的锗含量

建立高通量密闭微波消解样品-电感耦合等离子体质谱仪(inductively coupled plasma mass spectrometer,ICP-MS)测定食品中锗含量的检测方法。试验研究高通量密闭微波消解样品和高压密闭罐消解样品测试结果比对试验、锗的干扰试验、方法的检出限、精密度和准确度试验、加标回收试验,结果表明:方法检出限为:0.9 μg/kg;相对标准偏差(relative standard deviation,RSD)为5.1 %~17.8 %之间;相对误差(relative error,RE)为2.7 %~12.6 %之间;加标回收率在94.0 %~105 %之间,满足DD2005-03《区域生态地球化学调查评价样品分析技术要求》中的质量控制要求。对不同种类食品标准物质进行测定验证方法的准确度,测定结果与标准值相吻合。     

不同前处理方式对电感耦合等离子体发射光谱法测定饲料中4种微量元素的影响

目的 本文采用电感耦合等离子体发射光谱法,比较分析微波消解法和湿法消解法对饲料中铜、铁、锰、锌测定结果的影响。方法 以微波消解法处理测定的结果为对照,通过不同消解方式处理饲料和标准物质,测定其中铜、铁、锰、锌的含量,比较分析了湿法消解对饲料中铜、铁、锰、锌含量测定的影响。结果表明,仪器在最优条件下,仪器调制最优条件,在0.02-20.0mg/L（铜、铁、锰、锌）的浓度范围内,四种微量该方法各元素测量线性良好,相关系数均大于0.9999,检出限范围在为0.025～0.160 mg/kg。,定量限为0.083～0.533 mg/kg。研究发现微波消解法和湿法消解法消化饲料样品均能获得令人满意的回收率和重复性,回收率为95.7%～104.9%,相对标准偏差均小于3%。在实际样品测量中,对比分析发现微波法与湿法对各4种元素的测量结果无显著差异。因此,结论 湿法消解在日常试验实验中可用于替代微波法进行样品前处理。     

微波消解-氢化物发生双道原子荧光光谱法同时测定糖蜜中的砷和汞

建立了微波消解-氢化物发生双道原子荧光光谱法同时测定糖蜜样品中砷和汞的分析方法。实验探索了酸的种类比例、固液比、微波强度、消解时间等各种微波消解条件,并对工作条件进行了优化。仪表检出限为砷0.0704μg/L,汞0.0089μg/L;精密度为砷1.13%,汞0.49%;样品加标回收率为砷96.1%～107.6%,汞102.3%～105.1%。应用该方法对广西某制糖集团下属公司的糖蜜中砷和汞的含量进行了分析,结果令人满意。     

微波消解-原子荧光法测定食用油中总砷的方法优化

采用微波消解-原子荧光法测定食用油中的重金属总砷含量,重点对样品前处理条件、标准曲线、仪器参数等进行了优化.在优化微波前处理和仪器条件下,砷含量在0～4μg/L范围内线性相关,相关系数r=0.999 8,加标回收率为82%～105%.微波消解方法简便、快速、试剂消耗少,原子荧光法灵敏度高,测定结果准确,检出限为1μg/L,完全满足实验室日常工作和产品卫生指标控制的需要.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.