Determination and distribution of polycyclic aromatic hydrocarbons in native vegetable oils,smoked fish products,mussels and oysters,and bream from the river Elbe

Twenty eight native vegetable oils were analyzed for polycyclic aromatic hydrocarbons. Generally PAH concentrations were low, but olive oils showed significantly higher contamination by light PAH ranging from 53 to 105.6 μg/kg. Muscle and liver samples of bream from the river Elbe contained little or no detectable amounts of PAH, whereas fresh and canned oysters and mussels showed higher contaminations. Highest PAH concentrations have been determined in “smoked oysters in oil” with 75.8 μg/kg benzo[a] pyrene for the oil and 12.2 μg/kg for the oyster meat.     

Applications of electron paramagnetic resonance spectroscopy to study interactions of iron proteins in cells with nitric oxide

Nitric oxide and species derived from it have a wide range of biological functions. Some applications of electron paramagnetic resonance (EPR) spectroscopy are reviewed, for observing nitrosyl species in biological systems. Nitrite has long been used as a food preservative owing to its bacteriostatic effect on spoilage bacteria. Nitrosyl complexes such as sodium nitroprusside, which are added experimentally as NO-generators, themselves produce paramagnetic nitrosyl species, which may be seen by EPR. We have used this to observe the effects of nitroprusside on clostridial cells. After growth in the presence of sublethal concentrations of nitroprusside, the cells show they have been converted into other, presumably less toxic, nitrosyl complexes such as (RS)₂Fe(NO)₂. Nitric oxide is cytotoxic, partly due to its effects on mitochondria. This is exploited in the destruction of cancer cells by the immune system. The targets include iron–sulfur proteins. It appears that species derived from nitric oxide such as peroxynitrite may be responsible. Addition of peroxynitrite to mitochondria led to depletion of the EPR-detectable iron–sulfur clusters. Paramagnetic complexes are formed in vivo from hemoglobin, in conditions such as experimental endotoxic shock. This has been used to follow the course of production of NO by macrophages. We have examined the effects of suppression of NO synthase using biopterin antagonists. Another method is to use an injected NO-trapping agent, Fe–diethyldithiocarbamate (Fe–DETC) to detect accumulated NO by EPR. In this way we have observed the effects of depletion of serum arginine by arginase. In brains from victims of Parkinson's disease, a nitrosyl species, identified as nitrosyl hemoglobin, has been observed in substantia nigra. This is an indication for the involvement of nitric oxide or a derived species in the damage to this organ.     

AES法和AAS法测定食品、药物中微量元素的进展

综述了80年代以来原子发射光谱（AES）法和原子吸收光谱（AAS）法在食品和药物中微量元素分析的应用进展，内容包括，样品的预处理和进样技术，ICP-AES法和其他AES法。FAAS法，GFAAS法，HG-AAS法和冷蒸气AAS法等方面的应用及发展状况。     

Sample preparation for routine high-performance liquid chromatographic determination of retinol palmitate in emulsified nutritional supplements by solid-phase extraction using monosodium L-glutamate as dissolving agent

Retinol palmitate (vitamin A, 73.3 microg/g) in an emulsified nutritional supplement was determined by solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with fluorescence detection (excitation 350 nm, emission 480 nm) using monosodium L-glutamate as a dissolving agent to obtain higher recovery of vitamin A from the emulsified sample solution. A Bond Elut C2 cartridge (500 mg) was chosen for SPE after comparison with 16 other types. A sample solution was applied to a conditioned Bond Elut C2 cartridge and then vitamin A was eluted with ethanol followed by HPLC. The proposed method was simple, rapid (sample preparation time by SPE: ca. 8 min, retention time: ca. 8 min), sensitive [detection limit: ca. 0.1 pg/injection (100 microl) at a signal-to-noise ratio of 3:1], highly selective and reproducible (relative standard deviation (RSD): ca. 2.9% (n = 5), between-day RSD ca. 3.7 (5 days). The recovery of vitamin A was over 90% by the standard addition method.     

高效液相色谱法同时测定食品中安赛蜜、糖精、苯甲酸、山梨酸和咖啡因

用KromasilC1 8柱 ,以甲醇 :0 .5g/L柠檬酸铵 (42 5 :5 75 )为流动相 ,在波长 2 1 5nm ,柱温 40℃下测定了食品中的安赛蜜、糖精、苯甲酸、山梨酸和咖啡因。方法RSD 0 .6 2 %～ 1 48% ,回收率 1 0 0 .7%～ 1 0 3 % ,相关系数r>0 .9998;应用于可乐、汽水、果奶等测定。     

β修正吸光光度法测定食品中微量铅

用 β修正二硫腙光度法对铅进行测定。结果表明此法能准确消除显色液中剩余二硫腙吸收影响 ,使测定误差减小 ,其灵敏度比经典的单波长二硫腙法提高 1.3倍 ,相对标准偏差为0 82 %～ 3.95 % ,加标回收率为 95 %～ 10 1%。方法应用于食品中铅的测定 ,结果满意。     

Automated analytical microarrays: a critical review

Microarrays provide a powerful analytical tool for the simultaneous detection of multiple analytes in a single experiment. The specific affinity reaction of nucleic acids (hybridization) and antibodies towards antigens is the most common bioanalytical method for generating multiplexed quantitative results. Nucleic acid-based analysis is restricted to the detection of cells and viruses. Antibodies are more universal biomolecular receptors that selectively bind small molecules such as pesticides, small toxins, and pharmaceuticals and to biopolymers (e.g. toxins, allergens) and complex biological structures like bacterial cells and viruses. By producing an appropriate antibody, the corresponding antigenic analyte can be detected on a multiplexed immunoanalytical microarray. Food and water analysis along with clinical diagnostics constitute potential application fields for multiplexed analysis. Diverse fluorescence, chemiluminescence, electrochemical, and label-free microarray readout systems have been developed in the last decade. Some of them are constructed as flow-through microarrays by combination with a fluidic system. Microarrays have the potential to become widely accepted as a system for analytical applications, provided that robust and validated results on fully automated platforms are successfully generated. This review gives an overview of the current research on microarrays with the focus on automated systems and quantitative multiplexed applications. Figure MCR 3: A fully automated chemiluminescence microarray reader for analytical microarrays     

Certified reference materials as a quality tool in food control: much used—often misused—sometimes abused

Certified reference materials (CRMs) are important tools in the quality control of food analyses. There are, however, many ways in which CRMs can be abused and misused. It can be due to ignorance, as well as to overuse of expensive materials. The major drawback of CRMs is probably that the analyst knows the level of the analyte. The statistical evaluation of CRM results in reports and publications is often limited to a comparison between the found and the certified levels, which yields little, and sometimes erroneous, information. Recoveries based on CRMs often give a picture that is far too bright, with little consideration of uncertainties. The way the use of CRMs is described in most scientific journals is often very crude and shows that CRMs are seldom used to their full capacity. The objective of this paper is to try to summarise the ways in which a CRM can be misused and thereby put into focus how to make better use of such materials. It also gives examples on how to evaluate CRMs, using a procedure that was recently introduced by the Nordic Committee on Food Analysis.     

Synchronous fluorescence spectroscopy for quantitative determination of virgin olive oil adulteration with sunflower oil

Adulteration of extra virgin olive oil with sunflower oil is a major issue for the olive oil industry. In this paper, the potential of total synchronous fluorescence (TSyF) spectra to differentiate virgin olive oil from sunflower oil and synchronous fluorescence (SyF) spectra combined with multivariate analysis to assess the adulteration of virgin olive oil are demonstrated. TSyF spectra were acquired by varying the excitation wavelength in the region 270–720 nm and the wavelength interval (Δλ) in the region from 20 to 120 nm. TSyF contour plots for sunflower, in contrast to virgin olive oil, show a fluorescence region in the excitation wavelength range 325–385 nm. Fifteen different virgin olive oil samples were adulterated with sunflower oil at varying levels (0.5–95%) resulting in one hundred and thirty six mixtures. The partial least-squares regression model was used for quantification of the adulteration using wavelength intervals of 20 and 80 nm. This technique is useful for detection of sunflower oil in virgin olive oil at levels down to 3.4% (w/v) in just two and a half minutes using an 80-nm wavelength interval.