Teil II: Ergebnisse bei der Bestrahlung einzelner Nahrungsmittelgruppen (Zusammenfassender Bericht)

Nachdem im ersten Teil dieser Arbeit [170] einige Grundprobleme der Nahrungsmittelbestrahlung behandelt wurden, sollen nun die bei der Bestrahlung wichtiger Nahrungsmittelgruppen erzielten Ergebnisse dargelet und eine Einschätzung der Entwicklungstendenzen versucht werden.     

XPS analysis of bio‐organic systems

A survey of the literature is made for the XPS analysis of food products (mainly spray‐dried powders, which reveal a considerable surface enrichment in lipids) and of microorganisms and related systems (extracellular polymer substances and biofilms). This survey is used as a background for discussions and recommendations regarding methodology. Sample preparation methods reviewed are freeze drying, analysis of frozen hydrated specimens and adsorption of surface‐active biocompounds on model substrates. Peak decomposition is a way to increase the wealth of information provided by the XPS spectra. It should be performed after a check that sample charge stabilization is satisfactory. Moreover, ensuring the precision needed to make comparisons within sets of samples may involve a trade‐off between imposing constraints and generating information. The examination of correlations between spectral data in the light of chemical guidelines is useful to validate or improve peak decomposition and component assignment, and may also upgrade the chemical information regarding speciation. Further upgrading may be achieved by expressing marker XPS data in terms of concentrations of compounds of interest. Different methods of computation are discussed, providing a composition in terms of ingredients, classes of biochemical compounds, or various organic and inorganic compounds. As an alternative or complement to this deterministic approach, multivariate analysis of suitable spectral windows provides spectral components, which may be used for comparing samples, and which may have a direct chemical relevance or be used to identify features of interest. Copyright © 2011 John Wiley & Sons, Ltd.     

食用色素的吸附伏安法分析

柠檬黄,胭脂红皆为合成食用色素,其原料本胺具有毒性,我国严格限定其使用范围和用量。测定混合色素多用色谱法,导数光度法。都需将试样先行分离,灵敏度较低。Fogg等用脉冲极谱法测定饮料中的混合色素。我们发现,混合色素柠檬黄和胭     

Computer-assisted analysis of chaos in a three-species food chain model

In this paper, a three-species food chain model with Holling type IV and Beddington–DeAngelis functional responses is formulated. Numerical simulations show that this system can generate chaos for some parameter values. But the mechanism behind chaos is still unclear only through numerical simulations. Then, using the topological horseshoe theories and Conley–Moser conditions, we present a computer-assisted analysis to show the chaoticity of this system in the topological sense, that is, it has positive topological entropy. We prove that the Poincaré map of this model possesses a closed uniformly hyperbolic chaotic invariant set, and it is topologically conjugate to a 2-shift map. At last, we consider the impact of fear on this three-species model. It is an important factor in controlling chaos in biological models, which has been validated in other models.      

微流控芯片电泳在食品安全与环境污染检测中的应用

微流控芯片电泳具有样品和试剂消耗量小、分析速度快、分离效率高以及便于微型化等特点,特别适合于食品安全和环境污染相关的现场快速检测。该文综述了微流控芯片电泳技术在食品安全与环境污染检测方面的研究进展,着重介绍了该技术在食品中有害物质残留、非法食品添加剂以及环境样品中有害无机离子、有机污染物等目标物检测方面的典型应用实例,在此基础上初步讨论了微流控芯片电泳走向实际应用面临的问题和可能的解决办法。     

液相色谱-串联质谱法测定食品中甜味剂和抗氧化剂

建立了液相色谱-四级杆飞行时间串联质谱联用技术同时测定4种甜味剂(安赛蜜、糖精钠、甜蜜素、阿斯巴甜)及2种抗氧化剂(叔丁基对苯二酚、丁基羟基茴香醚)的方法.试验采用Extend-C18色谱柱分离与ESI(-)检测,以乙腈-1 mmol/L乙酸铵为流动相梯度洗脱,在6 min内实现6种目标物的快速分离,检测限为0.250 0~5.00 0 ng/m L,日间精密度小于10.71%(n=3),液态样品平均回收率为83.24%~118.3%.方法准确、灵敏,可快速检测食品中的甜味剂和抗氧化剂.     

液相色谱-串联质谱法快速筛查减肥类中药及保健品中非法添加30种化学药

建立了中药及保健品中30种减肥类化学药的高效液相色谱-串联质谱(LC-MS/MS)快速筛查方法。实验优化了前处理方法、色谱分离条件和质谱参数。样品采用甲醇超声萃取,Agilent poroshell 120 ECC18(4.6 mm×100 mm,2.7μm)色谱柱分离,流动相为乙腈-水溶液(含10 mmol/L甲酸铵,0.1%甲酸,10%甲醇),梯度洗脱,流速0.25 m L/min,采用正负离子切换模式的电喷雾质谱检测,多反应选择离子监测(MRM)。该方法能同时筛查30种化学药,覆盖面广,简便、快速、准确可靠,已用于减肥类中药及保健品中非法添加化学药的筛查及检测。     

藏红T共振瑞利散射光谱法测定保健食品中的透明质酸钠

建立藏红T共振瑞利散射光谱法测定保健食品中透明质酸钠的含量。在p H 5.00的Britton–Robinson缓冲介质中,藏红T与透明质酸钠反应形成化合物,使溶液共振瑞利散射急剧增强并产生相应的散射光谱,其最大散射峰位于335 nm,5.0×10~(–4) mol/L藏红T溶液用量为0.70 m L,反应时间为15 min。透明质酸钠的质量浓度在0.06~3.0mg/L范围内与共振瑞利散射增强程度成良好的线性关系,线性相关系数为0.999 2。方法检出限为19.8μg/L,测定结果的相对标准偏差为3.36%~4.52%(n=6),加标回收率为92.4%~103.0%。该方法灵敏度高、选择性好、操作简便,适用于保健食品中透明质酸钠的测定。     

超高效液相色谱-大气压化学电离-三重四极杆质谱联用法快速测定食品中苯并[a]芘

建立了快速检测食品中苯并[a]芘的超高效液相色谱-三重四极杆质谱联用(UPLC-MS/MS)分析方法。样品用正己烷提取后,经分子印迹固相萃取柱净化,以甲醇和水作为流动相进行梯度洗脱,在XBridge BEH C18柱上实现分离,大气压化学电离(APCI)-三重四极杆质谱正离子MRM方式检测,以苯并[a]芘-d12作为内标的稳定同位素稀释法定量。方法的线性范围为0.07~50μg/kg,定量限为0.07μg/kg。平均加标回收率为86%~104%,相对标准偏差为2.3%~14%。该方法灵敏、准确,适用于食品中苯并[a]芘的测定,已应用于实际样品的检查。     

Pendimethalin determination in natural water, baby food and river sediment samples using electroanalytical methods

This work describes the electroanalytical determination of pendimethalin herbicide levels in natural waters, river sediment and baby food samples, based on the electro-reduction of herbicide on the hanging mercury drop electrode using square wave voltammetry (SWV). A number of experimental and voltammetric conditions were evaluated and the best responses were achieved in Britton-Robinson buffer solutions at pH 8.0, using a frequency of 500 s^− 1, a scan increment of 10 mV and a square wave amplitude of 50 mV. Under these conditions, the pendimethalin is reduced in an irreversible process, with two reduction peaks at − 0.60 V and − 0.71 V, using a Ag/AgCl reference system. Analytical curves were constructed and the detection limit values were calculated to be 7.79 μg L^− 1 and 4.88 μg L^− 1, for peak 1 and peak 2, respectively. The precision and accuracy were determinate as a function of experimental repeatability and reproducibility, which showed standard relative deviation values that were lower than 2% for both voltammetric peaks. The applicability of the proposed methodology was evaluated in natural water, river sediments and baby food samples. The calculated recovery efficiencies demonstrate that the proposed methodology is suitable for determining any contamination by pendimethalin in these samples. Additionally, adsorption isotherms were used to evaluate information about the behavior of pendimethalin in river sediment samples.