SPE-GC/MS外标法测定酒中氨基甲酸乙酯

建立固相萃取(SPE)结合气相色谱质谱联用仪(GC/MS)测定酒中氨基甲酸乙酯。试样经硅藻土固相萃取柱净化,乙酸乙酯/乙醚洗脱后,气相色谱-质谱联用仪测定,利用选择离子监测模式及外标法对其进行定性、定量。氨基甲酸乙酯在10—120μg/L浓度范围内线性关系良好,r2=0.9993,检测限为1.6μg/kg,定量限为3.0μg/kg,加标回收率在81.0%—97.4%之间,RSD为2.6%—5.5%(n=6)。应用此方法,对市场销售的各种酒进行了检测,氨基甲酸乙酯的含量在5.8—93.6μg/kg之间。此方法可靠、便捷,净化效果好,灵敏度、准确度均满足检测要求,可作为酒中氨基甲酸乙酯含量的检测方法。     

固相萃取-高效液相法测定芝麻油中苯并(a)芘

建立一种快速、高效测定芝麻油中苯并(a)芘的固相萃取-高效液相色谱(SPE-HPLC)方法。样品前处理采用硅胶固相萃取柱串联氧化铝固相萃取小柱,稀释液和淋洗液选择正己烷,洗脱液选择二氯甲烷,在40℃下氮吹干后,乙腈复溶后检测。采用Waters RP C18色谱柱(4.6 mm×250 mm,5μm)分离,以乙腈-水(90∶10)作为流动相,用荧光检测器检测,外标法峰面积定量。结果表明,苯并(a)芘在1.00 ng/m L~20.00 ng/m L浓度范围内线性良好,相关系数r2为0.999 8,检出限为0.05μg/kg,定量限为0.16μg/kg,加标回收率达到92.2%~98.5%。     

液相色谱串联质谱法测定饲料中高氯酸盐含量

目的建立液相色谱串联质谱检测饲料中高氯酸盐含量的方法。方法饲料样品经乙腈-水(2:1,V:V)超声提取,高速离心后,上清液经石墨炭黑固相萃取柱净化,液相色谱串联质谱测定,内标法定量。结果高氯酸盐在0～100ng/mL浓度范围内呈良好线性关系(r2=0.9998)。本方法的定量限为15.0μg/kg。高氯酸盐在15～150μg/kg添加浓度范围内,回收率为95.1%～102.4%,相对标准偏差为1.13%～9.82%。结论本方法前处理简单,具有较高准确度、灵敏度、稳定性,可以满足饲料中高氯酸盐的含量检测。     

Florisil固相萃取-HPLC-FLD法测定烤肉中15种多环芳烃

建立一种Florisil固相萃取-HPLC-FLD法同时测定烤肉中15种多环芳烃(PAHs)的方法。样品经超声提取,Florisil固相萃取柱净化,通过高效液相色谱分离,外标法定量。结果表明, 15种PAHs的质量浓度在1～50 ng/mL范围内与色谱峰面积呈良好线性关系,线性相关系数(r)大于0.999 5;在5, 10和20μg/kg的加标水平下,平均回收率分别为73.1%～87.5%, 78.2%～93.3%和85.3～97.5%,相对标准偏差为2.0%～5.0%, 1.8%～5.0%和1.1%～3.1%;检出限(S/N=3)与定量限(S/N=10)分别为0.33～3.3μg/kg和1.0～10μg/kg。     

液相色谱-质谱/质谱法检测饲料中四环素类药物残留

建立液相色谱-质谱/质谱法测定饲料中四环素类(四环素、土霉素、金霉素、强力霉素)药物残留的方法,旨在提高检测效率和检测限度。实验中,采用Na2EDTA-Mcllvainc缓冲溶液提取样品,经Phenomenex Strata-X固相萃取柱净化,进行液相色谱-质谱/质谱法分析。结果表明:四环素类标准品3个添加浓度20、50和100μg/kg的平均回收率为93%~103%,相对标准偏差小于15%,四环素类药物的检测定量限(LOQ):20μg/kg,检出限:5μg/kg。标定曲线的线性范围:10~200μg/L,R0.998。此方法适用于饲料中四环素类药物残留检测。     

分子印迹固相萃取-高效液相色谱法测定植物油中11种多环芳烃

建立了同时测定植物油中11种多环芳烃的分子印迹固相萃取-高效液相色谱荧光检测方法。样品使用环己烷溶解,经分子印迹固相萃取柱净化,得到的洗脱液氮吹后使用乙腈复溶,通过PAHs专用C_(18)色谱柱分离,采用高效液相色谱-荧光检测器定量检测。结果表明:本方法在0. 5～200 ng/mL线性关系良好,11种组分加标回收率在63.5%～118.6%,相对标准偏差1.4%～18.2%,最低检出限为0.03～1.50μg/kg,定量限为0. 10～5. 00μg/kg。本方法前处理简单、快速、灵敏度高,适合植物油中多环芳烃的快速准确测定。     

固相萃取-超高效液相色谱-三重四极杆质谱法同时测定饲料中5种雌激素

建立了固相萃取-超高效液相色谱-三重四极杆质谱法(SPE-UPLC-MS/MS)同时测定饲料中双烯雌酚、己烯雌酚、己烷雌酚、17α-雌二醇和17β-雌二醇5种激素的检测方法。饲料样品采用乙醚振荡提取、三氯乙酸除蛋白和正己烷除脂,提取液通过Max固相萃取柱净化,经过Athena C18-WP色谱柱(2.1×150 mm,5μm)分离,以0.25‰氨水和乙腈进行梯度洗脱,负离子电喷雾电离多反应监测模式进行定性和定量分析。同时优化液相色谱条件和质谱参数,以提高灵敏度,并以17β-雌二醇-D3和己烯雌酚-D8为内标进行定量。结果显示,5种激素在0～10μg/L范围内线性相关系(r)≥0.9994;5种雌激素的定量限均为1.0μg/kg;各雌激素的加标浓度为1.0μg/kg、2.0μg/kg、5.0μg/kg时,其加标回收率均在70.20%～114.37%之间,相对标准偏差为0.15%～9.08%(n=6)。结果表明,该方法前处理简单、准确可靠,适用于饲料中5种雌激素的检测。     

高效液相色谱-串联质谱法测定大米中高氯酸盐含量

目的建立高效液相色谱-串联质谱法测定大米中高氯酸盐的含量。方法样品提取液经过固相萃取柱快速净化处理后去除基质干扰物,采用Thermo Acclaim TRINITY P1色谱柱分离,以乙腈-20 mmol/L甲酸铵为流动相进行梯度洗脱,流速为0.3mL/min,柱温30℃,外标法定量检测。结果在高氯酸盐浓度为1.0～100.0 ng/mL的范围内的线性相关系数较好(r=0.999),检出限为4.0μg/kg,定量限为10.0μg/kg,高、中、低3个浓度水平的加标回收率在82.3%～93.2%之间,测定值的相对标准偏差小于5%(n=6)。结论该方法简便快捷、灵敏可靠,适用于大米中高氯酸盐的快速检测。     

同位素稀释超高效液相色谱-串联质谱法检测牛奶中类固醇激素

目的建立一种牛奶中睾酮、孕酮及氢化可的松类固醇激素同位素稀释超高效液相色谱-串联质谱法(isotope dilution-ultra performance liquid chromatography-tandem mass spectrometry,ID-UPLC-MS/MS)的分析方法。方法样品加氯化钠盐析、沉淀蛋白,经0.5%甲酸乙腈溶液提取,正己烷反萃取后,氮吹干燥,用10%甲醇溶液复溶,过HLB固相萃取柱净化,甲醇溶剂洗脱、氮吹干燥,复溶后上机检测。采用0.1%甲酸(A)和0.1%甲酸-甲醇(B)作为流动相进行梯度洗脱,采用电喷雾离子化(ESI+)质谱多级反应监测模式(multiple reactions monitoring,MRM)对分析物的定量离子和定性离子进行监测。结果本方法在8 min内完成3种目标化合物的分离分析。3种目标化合物在0.1~100μg/kg的浓度范围内有良好的线性关系,相关系数r2均大于0.9985。睾酮、孕酮和氢化可的松的方法检出限分别为0.043、0.027和0.085μg/kg,方法定量限分别为0.122、0.083和0.227μg/kg。在1、10和50μg/kg 3个添加水平下,3种目标化合物同位素稀释法回收率为97.29%~102.71%,日内相对标准偏差为0.30%~2.96%,日间相对标准偏差为0.84%~4.08%。结论该方法快速、准确、稳定性高,适用于同时检测牛奶中3种类固醇激素含量。     

固相萃取-气相色谱-串联质谱法测定蔬菜中的 16种多环芳烃

目的建立固相萃取-气相色谱-串联质谱法测定蔬菜中16种多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的分析方法。方法样品经正己烷-二氯甲烷匀浆提取,经中性硅胶-中性氧化铝复合固相萃取柱净化后,用多反应监测(multiple-reaction monitoring,MRM)正离子扫描方式进行检测,气相色谱-串联质谱法测定,内标法定量。结果 16种目标物在2~250 ng/m L范围内呈线性关系良好,方法的检出限(S/N=3)为0.09~0.51μg/kg,定量限(S/N=10)为0.31~1.68μg/kg。在2、5、20μg/kg 3个加标水平下的平均回收率为添加平均回收率范围为70.6%~109.2%,相对标准偏差(RSD)为1.95%~10.4%。结论该方法选择性好、抗干扰能力强,能满足国内外法规的要求,可用于蔬菜中多环芳烃残留的日常检测。     

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.     

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.     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.