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1.
紫外分光光度法测定富硒麦芽中硒元素   总被引:1,自引:0,他引:1  
采用单因素试验方法,对紫外分光光度法测定硒元素含量的条件进行了优化筛选,并以2,3-二氨基萘荧光法作对照,通过测定富硒麦芽中的硒元素含量开展方法评价。结果表明:在30℃、pH1.5-2.0范围内,添加5mL邻苯二胺(1g/L)和2mL乙二胺四乙酸二钠(EDTA-2Na)(1g/L),反应22min;甲苯萃取振荡时间为6min条件下进行样品制备处理,在波长333nm处测定,其吸光度值较高且稳定;经验证样品中Se^4+含量在2.28×10^-6mol/L-2.53×10^-5mol/L范围时,线性关系良好,线性方程为A=0.1085c+0.0020(r^2=0.9994);加标回收率为97.5%~105.7%。  相似文献   

2.
谷氨酸脱羧酶活力测定中GABA比色定量方法研究   总被引:3,自引:0,他引:3  
建立了谷氨酸脱羧酶活力测定中γ-氨基丁酸比色测定方法,该方法灵敏度高、精确性和重现性好。测定程序为:取酶反应液0.4ml,加入Na2CO3(1mol/L)0.1ml、pH10.0硼酸盐缓冲液(0.2mol/L)0.5ml、6%苯酚1ml,混匀,于室温下(20℃)在5min内加入5.2%NaClO溶液1ml,混匀后放置4~8min,然后沸水浴10min,立即冰浴20min,待溶液出现蓝绿色后,加入2.0ml60%乙醇溶液,混匀后于20℃水浴中放置20~40min,测定640nm处的吸收值。经采用比色法和高效液相色谱法对谷氨酸脱羧酶酶反应液进行测定,两种方法的测定结果相对误差为4.91%。  相似文献   

3.
在H2SO4介质中,亚硝酸盐对KBrO3氧化铬天青S褪色反应有催化作用,基于此建立了催化光度法测定亚硝酸盐的新方法。讨论了H2SO4用量、铬天青S用量、KBrO3用量、加热温度及反应时间的影响,确立了最佳反应条件。在选择的条件下,该方法的线性范围为0.04~1.35mg/L,检出限为6.6×10-3 mg/L。该方法用于香肠中亚硝酸盐的测定,结果满意。  相似文献   

4.
研究了以壳聚糖为载体交联-吸附单宁酸酶后的化学特性。结果表明:固定化单宁酸酶(简称“ITA”)的最适反应pH为3.0,原酶(简称“TA”)为5.5;ITA最适反应温度为50℃,TA为40℃;ITA的Km(app)为1.3845×10(-1)mol/L,TA为6.7500×10(-5)mol/L;ITA在pH3.0~8.0的范围内残存酶活大于60%,ITA在pH3.0~6.0范围内残存酶活大于60%;ITA在80℃的水浴中保温1h,酶活力仍未见下降,而TA在60℃水浴中保温30min酶已失活;ITA和TA在4℃和30℃的条件下,贮藏20d后,ITA的残存活性大于40%,TA的残存活性小于20%。  相似文献   

5.
乳中磺胺甲基嘧啶残留酶联免疫测定   总被引:10,自引:1,他引:9  
以BSA为载体合成两种不同摩尔比值(1:13和1:42)磺胺甲基嘧啶抗原,并比较其免疫原性;以OA为载体合成一种包被抗原;用过氧化物酶标以鼠抗免IgG;建立乳中磺胺甲基嘧啶残留酶联免疫测定。抗体亲和常数分别为1.28×107(1:42)和3.21×107(1:13)。ELISA测定磺胺甲基嘧啶工作浓度5~220ng/ml(1.87×10-8~8.2×10-7mol/L),检测限为2.4ng/ml,回收率为88~118%,与磺胺二甲基嘧啶和磺胺噻唑交叉反应率分别为6.0%和0.84%,与碘胺二甲氧嘧啶和磺胺咪无交叉反应。  相似文献   

6.
尚磊  窦强 《山东食品科技》2012,(11):434-436
目的建立测定安神颗粒中酸枣仁皂苷A及B含量的方法,提供该制剂质量控制标准。方法应用高效液相色谱法.蒸发光散射检测器(HPLC—ELSD),Kromasil C18色谱柱(4.6mm×200mm,5μm),流动相:甲醇-水-冰醋酸(65:35:1),流速:1.0mL/min,柱温25℃,氮气流速2.0L/min,漂移管温度94℃,测定安神颗粒中酸枣仁皂苷A和B含量。结果酸枣仁皂苷A及B平均回收率分别为100.2%(RSD=1.21%)和99.88%(RSD=1.32%)。结论此方法操作简便,结果准确、可靠,可有效控制制剂的质量。  相似文献   

7.
选取3个小麦品种作为试验材料,以邻苯二酚为底物,采用分光光度法在410nm处测定小麦多酚氧化酶(PPO)的活性,研究温度、pH值、底物浓度对其活性的影响以及酶促动力学常数Km,结果表明:小麦多酚氧化酶的最适温度范围为60~75℃.最适pH值为4.0~4.6,描述的单底物酶促反应动力学,相应的动力学参数Km=0.19mol/L.vmax=4.04×102(mol·L^-1)·min-1。  相似文献   

8.
流动注射胶束增容法测定水环境中的铜,方法简便快速,便于水环境中铜离子的测定。在硼砂盐酸缓冲溶液中,铜与铬天青S以及溴化十六烷基三甲基铵(CTMAB)反应生成黄绿色的络合物,在605nm波长下可以检测。在最佳检测条件下,运用该方法测定铜离子可以得到线性良好且范围广的标准曲线,检测范围为5~40μg/L、40~200μg/L;检测限为0.76μg/L;相对标准偏差为1.59%(n=11)。试验得到的回收率为90.2%~104%。  相似文献   

9.
软饮料中Vc含量的测定   总被引:7,自引:0,他引:7  
利用I3-与抗坏血酸的定量反应关系,提出了碘酸钾与碘化钾在弱酸性条件下成I3-来间接测定软饮料中抗坏血酸的紫外分光光度法,最大吸收波长290nm,KIO3含量在0~5.0×10-6mol/L范围内线性良好,回归方程为A=1.25×105C+0.065,线性相关系数v=0.9999,表观摩尔吸光系数ε290=1.25×105L/mol.cm.精密度高,回收率在96%~100%。  相似文献   

10.
建立了一种简单、快速测定甜菜糖蜜中甜菜碱的方法,即样品经去离子水提取,碱式醋酸铅脱色后,采用高效液相色谱-DAD检测器测定甜菜碱的含量。色谱柱为AgilentZorbaxNH2柱(Φ4.6mm×150mm,5Ixm),流动相为0.05mol/L KH2PO4溶液(pH=4.53),流速0.7mL/min,柱温30℃,检测波长195nm。试验结果表明:甜菜碱在0.1mg/mL~5.0mg/mL范围内线性良好,相关系数为0.998;加标回收率为99.5%~99.7%,相对标准偏差(RSD)为0.09%-1.06%(n=3)。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mM Na2B4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.  相似文献   

16.
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.  相似文献   

17.
An investigation is described in which various polyfunctional compounds were applied to wool in attempts to stabilize the temporary improvements in wrinkle-recovery brought about by ‘annealing’. Several reactive systems involving formaldehyde were found to produce the desired permanently improved wrinkle-recovery.  相似文献   

18.
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.  相似文献   

19.
20.
《造纸信息》2014,(8):79-79
Ministr y of Industr y and Information Technology confirmed that the main expected targets for energysaving and comprehensive utilization in 2014 are:energy consumption and CO2 emissions per unit of industrial added-value decreases by 4.5%,water consumption per ten thousand Yuan of industrial added-value decreases by7%,comprehensive utilization of industrial solid waste is further improved,and pollution emissions in key industries is markedly reduced.  相似文献   

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