响应面法优化浙贝母氨基酸提取工艺及含量测定

采用响应面法优化浙贝母氨基酸提取条件,建立柱前衍生-超高效液相色谱法(ultra-performance liquid chromatography,UPLC)测定浙贝母鳞茎中14种氨基酸含量方法,比较不同产地栽前与栽后浙贝母鳞茎氨基酸含量差异性。采用6 mol/L HCl 8 mL,超声30 min,在110℃下水解20 h提取浙贝母鳞茎中氨基酸,以异硫氰酸苯酯(phenyl isothiocyanate,PITC)柱前衍生化,UPLC检测,使用ACQUITY UPLC BEH C 18色谱柱(2.1 mm×150 mm,1.7μm),流动相A为0.1 mol/L乙酸钠溶液(冰醋酸调pH=6.5)-乙腈(体积比97∶3),B为乙腈-水(体积比4∶1),梯度洗脱,检测波长为254 nm,流速0.2 mL/min。14种氨基酸线性关系良好(r≥0.9992),平均加样回收率为95.12%~105.53%,RSD<3%,表明该方法准确可靠。不同产地栽前栽后浙贝母氨基酸含量具有一定差异。该方法确定了提取浙贝母氨基酸的最优条件,可用于浙贝母鳞茎中氨基酸的含量测定。     

超高效液相色谱法测定白酒中乳酸的含量

建立了超高效液相色谱法测定白酒中的乳酸含量的方法。样品经40℃旋转蒸发除醇后稀释、过滤,Waters Acquity UPLC HSS T3色谱柱(100mm×2.1mm×1.8μm)分离,以0.02mol/L KH2PO4为流动相,流速:0.1m L/min,进样量:1μL,二极管阵列检测器,检测波长208nm。在100-1000mg/L范围内呈线性相关,相关系数R2为0.999。白酒样品中加标回收率为99.9-101.0%,重现性RSD=1.30%。     

RP-HPLC法测定酸牛奶中纳他霉素含量

目的:建立测定酸牛奶中纳他霉素含量的反相高效液相色谱法。样品用甲醇萃取并沉淀蛋白质后进样,用ODS-2(250mm×4.6mm,5μm)色谱柱分离,流速为1.0mL/min,流动相:0.053mol/L乙酸铵与0.025mol/L氯化铵的缓冲液∶乙腈为70∶30(体积比)1L 5mL四氢呋喃,紫外检测波长302nm,RSD为0115%(n=10),标准曲线r=0.9962,平均回收率分别为96.5%。结论:本法具有操作简单、快速测定、灵敏度高、专属性好和准确性好等优点。     

HPLC法测定豆浆中的嘌呤含量

利用HPLC法对豆浆中的嘌呤物质进行检测分析,建立腺嘌呤、鸟嘌呤、黄嘌呤和次黄嘌呤4种嘌呤物质的多组分检测条件并进行方法评价。研究表明:利用Zorbax C18反相色谱柱(4.6 mm×250 mm,5.0μm),流动相以KH2PO4缓冲液(0.02 mol/L,p H 3.0),在流速1.0 m L/min,柱温25℃,进样量10μL,检测波长(λ1)为254 nm的条件下,豆浆中的4种嘌呤达到最好分离,其精密度和回收率小于2%。     

HPLC-UV法直接测定蔬菜提取物的叶酸含量

建立了高效液相色谱-紫外检测法(HPLC-UV)直接测定豆芽、西红柿、菠菜等蔬菜提取物中叶酸含量的方法。蔬菜浆液经60℃的0.1 mol/L KH_2PO_4-KOH缓冲液(p H=6.5)提取后,采用反相C_(18)色谱柱(250 mm×4.6 mm,5μm),紫外检测器,流动相为甲醇和用0.1 mol/L的KOH调节p H为6.5的0.1 mol/L KH_2PO_4的溶液(梯度变化0/100~30/70,v/v),流速1.2 m L/min,波长280 nm。方法在(0.1~50)μg/m L范围呈良好的线性关系,线性相关系数为0.9998,检测限为0.02μg/m L,加标回收率为93.34%~98.20%,RSD≤3.04%。叶酸测定结果为(湿基计):豆芽1.166μg/g、西红柿1.871μg/g、菠菜2.615μg/g。表明方法具有操作简便、快速、准确、精密等优点。     

高效液相色谱法测定发芽米胚芽中的γ-氨基丁酸

建立一种高灵敏度的邻苯二甲醛(OPA)柱前衍生荧光检测高效液相色谱法测定发芽米胚芽中γ-氨基丁酸(GA-BA)含量的方法。色谱柱为Shimadzu VP-ODS C18柱(250mm×4.6mm,5μm),流动相:0.05mol/L乙酸钠∶甲醇=60∶40,荧光发射波长λex 338nm,激发波长λem430nm。方法的线性范围为0.10～1.0μg/mL,检出限为0.005μg/mL。日间和日内测定的精密度分别为1.36%和2.54%,加标回收率在98.5%～99.8%。该法简便、快速、灵敏度高,可用于发芽米胚芽中GABA的质量控制。     

固相萃取-高效液相色谱荧光法测定食用油中苯并(a)芘

建立固相萃取-高效液相色谱法测定食用油中苯并(a)芘的检测方法。样品经苯并(a)芘专用SPE小柱净化、浓缩,沃特世反相C18(150 mm×4.6 mm,5μm)色谱柱进行分离,流动相为乙腈:水(95:5,体积比),流量1.0 mL/min,激发波长384 nm,发射波长406 nm。结果表明,苯并(a)芘在浓度范围0.2~50μg/kg内线性良好,相关系数为0.999 9,最低检出限为0.1μg/kg,精密度RSD3%,回收率88.6%~101%。本方法快速便捷、准确率高、重现性好、可同时处理大量样品,为食用油中苯并(a)芘的测定提供参考。     

文献导读

正面粉及面制品中过氧化苯甲酰的检测误区建立了高效液相色谱法同时检测面粉及面制品中过氧化苯甲酰和苯甲酸的方法。采用Waters XTerra RPC18(4.6 mm×250 mm,5μm)色谱柱,以乙腈-0.4%乙酸水溶液(60/40,体积比)为流动相;以1.0 m L/min的流速检测苯甲酸和过氧化苯甲酰(λ=230 nm)。在0.125μg/m L~100μg/m L范围内线性良好,最低检出限为0.5 mg/kg,加标回收率在     

磁分散固相萃取HPLC法测定纺织品中苯胺和联苯胺残留

建立了纺织品中苯胺和联苯胺两种残留物的磁性分散固相萃取高效液相色谱荧光分析方法。样品采用0.04%乙酸提取后,加入适量氨水调节pH至9,采用磁性亚微米粒子富集净化,在XDB C18柱(150 mm×4.6 mm i.d.,5μm)上以乙腈/50 mmol/L乙酸铵溶液(V/V=25/75)为流动相进行分离,采用荧光法检测,荧光检测波长苯胺为λex/λem=232 nm/329 nm、联苯胺为λex/λem=292 nm/383 nm。结果表明:苯胺和联苯胺在0.5~50.0μg/L范围内线性关系良好,相关系数均大于0.999,低、中、高3个加标水平下苯胺和联苯胺的回收率分别为96.2%~98.2%和93.0%~95.9%,日内相对标准偏差(RSD)均小于5.0%,检出限(LOD)分别为1.0μg/kg和0.4μg/kg,定量限(LOQ)分别为3.0μg/kg和1.5μg/kg。该方法具有前处理简单,方法检出限低,分析速度快等优点。     

液相色谱法测定水产品中链霉素残留

建立了水产品中链霉素残留的液相色谱检测方法,最佳条件为:样品经高氯酸提取后,用苯磺酸阳离子交换柱和C18固相萃取柱净化,以10mol/LAHS、0.4mol/LNQS的乙腈水溶液(体积比30∶70)为流动相,0.2mol/L氢氧化钠为衍生剂,激发波长263nm、发射波长435nm。在0.1～4μg/mL范围内,呈现良好线性关系,相关系数为0.99968,检出限为0.010mg/kg,方法的回收率>80%,批内、批间变异系数均小于10%。     

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.     

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.     

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.     

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.     

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.