白酒中乳酸的离子排斥色谱-直接电导检测分析

建立用直接电导检测的离子排斥色谱分离测定乳酸的方法。以Shim-pack SCR-102H色谱柱为分离柱,用对p-甲苯磺酸为流动相,考察流动相浓度、色谱柱温度及流速对分离和测定乳酸的影响。最佳色谱条件为以2.0mmol/L p-甲苯磺酸为流动相、流速1.0mL/min、柱温50℃。在此条件下,乳酸的保留时间约为8min,其他有机酸(甲酸、乙酸、柠檬酸和苹果酸)不干扰测定。乳酸的检出限为0.36mg/L,工作曲线的线性范围是1.0～100.0mg/L,峰面积的相对标准偏差(n=5)为0.9%。将方法应用于测定白酒中的乳酸,加标回收率为95.8%～98.5%。     

模拟移动床色谱法分离甜叶菊甙的工艺研究

以甜叶菊甙提取液为试验原料,研究模拟移动床色谱法分离甜叶菊甙中各因素对甜叶菊甙纯度和收率的影响。通过单因素和四元二次回归正交旋转组合试验,优化出模拟移动床色谱法分离甜叶菊甙的最佳工艺参数,即:切换时间12 min、进样质量浓度40 mg/m L、进料流速7.5 m L/min、水洗1流速10 m L/min、解吸流速15.4m L/min、再生流速7.26 m L/min、水洗2流速20.3 m L/min。各区域最优分配及连接方式:吸附区5根色谱柱三并两串,水洗1区3根色谱柱串联,解吸区6根色谱柱串联,再生区3根色谱柱一串两并,逆向进料,水洗2区3根色谱柱串联。此条件下所得甜叶菊甙纯度为80.69%,收率为93.48%。     

非抑制性离子色谱测定蓝藻培养液中碳酸氢根含量

建立了一种非抑制性阳离子色谱,电导检测器测定碳酸氢根的方法。采用Optimix C18/SCX阳离子交换柱,用稀释1000倍除碳酸氢钠的蓝藻母液等度洗脱,流速0.2 mL/min,柱温30℃,进样体积50 uL。在最佳的分离条件下,在1到500 mg/L的范围内线性相关系数为0.99946和相对标准偏差1%,n=8,加标回收率在100.15%-111.10%之间,最低检测限为0.5 mg/L。结果表明,该方法只需简单的前处理、无基体干扰、测定的准确度和灵敏度高,可应用于蓝藻培养液中的碳酸氢根的测定。     

离子色谱法测定小麦粉中溴酸钾和过氧化苯甲酰

建立了离子色谱快速同时检测小麦粉中溴酸钾和过氧化苯甲酰添加荆含量的分析方法.样品经100℃加热反应45 min处理后,通过水提取,采用Supp 5-250离子色谱柱;以5 mmol/L Na2CO3-乙腈作为流动相,在流速为0.6ml /min时进行等度洗脱,室温条件下分离待测物,并用化学抑制电导检测.结果显示,在选定色谱条件下溴酸根和苯甲酸根有效分离.且线性关系良好,溴酸钾回收率为97.0%～98.8%,过氧化苯甲酰回收率为92.5%～107.5%.表明该方法快速、准确,能同时测定小麦粉中溴酸钾和过氧化苯甲酰添加剂的含量.     

高效液相色谱和离子色谱测定水中短链脂肪酸的方法比较

从分离谱图、分析时间、线性范围、检出限、精密度和加标回收率角度,对离子色谱和高效液相色谱(HPLC)测定水中的短链脂肪酸的方法进行比较。HPLC使用SunFire~(TM)C18色谱柱,流动相为磷酸二氢钾溶液和甲醇,梯度洗脱,流速1.0 m L/min。离子色谱法使用Dionex~(TM)ATC-3色谱柱,流动相为不同浓度氢氧化钠溶液梯度洗脱,流速1.5 m L/min。结果表明:HPLC的分析时间、线性范围、检出限、保留时间精密度、峰面积精密度和加标回收率分别为14.5 min、0~1 200 mg/L、15.57~23.23 mg/L、0.079%~0.597%、1.12%~3.50%和96.1%~112.0%,离子色谱法的相应指标分别为13.0 min、0~20 mg/L、0.03~0.10 mg/L、0.000%~0.053%、1.18%~2.69%和98.2%~122.0%。HPLC线性检测范围宽,但检出限相对高。离子色谱法检出限低,但线性检测范围窄,过高的进样质量浓度使得分离效果不佳。应根据样品实际质量浓度,选择合适检测方法。     

RP-HPLC同时检测发酵液中7-脱氢胆固醇与胆固醇的研究

7-脱氢胆固醇是维生素D3的直接前体,试验研究了RP-HPLC同时检测发酵液中7-脱氢胆固醇及其前体胆固醇的方法和条件.应用Waters sunfire C18(φ416×150 mm,5μm)色谱柱,乙腈异丙醇=80:20(v:v)为流动相,1.0mL/min流速,38℃柱温,于波长210 nm紫外检测器检测.在此条件下,7-脱氢胆固醇和胆固醇呈现较好的分离和重现性,其保留时间分别为8.248min和9.598min左右,最低检测浓度分别为8mg/L和10 mg/L,平均回收率分别为99.53%和97.67%.     

非抑制型电导检测离子排斥色谱法测定江西白酒中的有机酸

建立了非抑制型电导检测离子排斥色谱法分离并测定6种有机酸(草酸、酒石酸、苹果酸、甲酸、琥珀酸、乙酸)的方法.以Ion Pac ICE-AS6色谱柱为分离柱,选用背景较低的稀苯甲酸溶液为淋洗液,考察了淋洗液浓度、流速、色谱柱温度对分离和测定有机酸的影响.通过实验确定最佳的色谱条件为:1.0mmol/L苯甲酸溶液作为淋洗液,流速0.45ml/min,柱温35℃.所测有机酸的检测限为0.0341～0.9045mg/L,相对标准偏差在0.13%～5.12%之间(n=5),回收率为90.75%～108.5%,方法具有较好的准确度和精密度.该法用于江西5个不同生产厂家23个白酒样品中有机酸的测定,结果令人满意.     

面粉中三聚氰胺的高效液相色谱——质谱法测定

建立了面粉中三聚氰胺的高效液相色谱一质谱测定方法.色谱条件:Kromasil C18柱(4.6mm×250mm,5μm),流动相:乙腈-0.1%(体积分数)甲酸(体积比5:95),流速O.4mL/min.采用正离子模式的电喷雾质谱检测,以一级质谱得到的准分子离子m/z 127作为母离子,进行碰撞诱导解离二级质谱分析,选择母离子和MS的碎片离子m/z85、109定性确证,提取m/z85、109、127三个离子质量色谱峰面积定量.线性范围为0.01～0.5 mg/L,检出限0.01mg/L,回收率为80%～99%.     

高效液相色谱快速分析亚麻籽环肽条件研究

采用高效液相色谱法分析亚麻籽环肽组成及相对含量。以14种亚麻籽环肽色谱峰平均分离度和分析效率作为指标,对不同色谱柱、进样量、梯度洗脱初始体积分数、流速、乙腈体积分数上升速率进行优化,并利用HPLC-ESI-MS进行定性分析。结果表明,高效液相色谱最优条件为:采用Kinetex■色谱柱,水、乙腈为流动相,进样量5μL,梯度洗脱程序为乙腈体积分数从40%以5%/min升至90%,流速1 m L/min。最优条件下亚麻籽环肽14个色谱峰分离度较好,平均分离度为1. 65,分析时间为9. 09 min,分离效率为10. 86。优化后的色谱条件可对市售亚麻籽、亚麻籽油以及亚麻籽粕中环肽组成进行有效分析。     

低压离子色谱法检测纺织品中5种游离醛研究

采用低压离子色谱-电导检测器,通过过氧化氢氧化法建立纺织品中5种醛(甲醛、乙醛、丙醛、丁醛和戊二醛)的快速检测方法。分析得出分离这5种游离醛的色谱条件为:柱长14 cm,洗脱流速为0.75mL/min,进样体积300μL,反应圈长度5.0 m。在这种条件下,各种醛的线性范围为0.1~15.0 mg/L,检出限在28~53μg/L之间,方法的回收率高于96.7%,该方法成功应用于纺织品中醛类的在线测定,准确度高。     

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.     

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.