食品中亚硝酸盐含量的测定

样品经沉淀蛋白质、除去脂肪,在弱酸性溶液中亚硝酸盐与对氨基苯磺酸重氮化后,再与盐酸萘乙二胺偶联生成紫红色的偶氮染料,用分光度法测定。经过校正,亚硝酸盐含量x（ug）与吸光度A之间在λmax=550nm处,具有良好的线性关系,在亚硝酸盐的量为0～25μg／25mL水溶液中,服从朗伯-比耳定律,其线性方程为A=0．0132蜀相关系数r^2=0．9982,利用此方法所测定的当地出售的部分食品中亚硝酸盐的含量均未超过相关标准。用分光光度法测定腌制蔬菜中亚硝酸的含量,方法简单、方便、快捷、实用。     

舟山群岛新区海产品中甲醛含量分析

应用高效液相色谱一紫外检测法分析了购至舟山国际水产城和沈家门东河市场的海产品中的甲醛。结果显示：不同市场购买的同种海产品中甲醛含量相差不明显,而不同种类的海产品中甲醛的含量差别巨大,其中龙头鱼甲醛含量最高达96．7mg／kg,大部分样品中甲醛含量小于5．0mg／kg,海鳗甲醛则未检出。     

几种蔬菜中亚硝酸盐含量的测定

用盐酸萘乙二胺比色法分别测定10种蔬菜中亚硝酸盐的含量,结果表明,在λ=538nm处,该络合物具有最大吸光度,在0～1μg·mL-1范围内,亚硝酸盐含量x(μg)与吸光度A之间具有良好的线性关系,其线性方程为y=0.0282x+0.0015,相关系数r=0.9997.从测定的芫荽等10种蔬菜当中,亚硝酸含量最高的为茄子...     

食用明胶中砷含量测定方法的讨论

<正> 一、前言 QB581-81中,砷的测定方法比较繁琐。GB6783-86中,虽然对测砷的方法作了改进,但某些辅助试剂没有必要加入。为此,我们参照两种方法,并查阅有关资料,进行了分析,简化了测定步骤,省去了某些辅助试剂,其结果与原测结果相符。二、原理分析 QB581-81中砷的测定原理是: 1.首先将胶样酸解; 2.砷以多价态形式存在,加入溴试剂,将砷全部氧化成五价:     

食品中亚硝酸盐的测定

对食品中亚硝酸盐的测定方法进行了综述。介绍了化学分析方法、光学分析法、色谱法、电化学分析法等,并对这些方法进行了比较。提出了亚硝酸盐测定方法的研究方向。     

泡菜中亚硝酸盐含量影响因素及安全食用期

文章以泡菜（甘蓝）为主要原料,研究了在室温（15～20℃）条件下影响亚硝酸盐含量的几种主要因素,结果表明：较高的食盐浓度可明显抑制豫硝酸盐的生成;在发酵过程中,不同的起始pH对亚硝酸盐含量也有较大的影响;在发酵后期,亚硝酸盐含量基本趋于稳定,且各种影响因素对成熟泡菜中亚硝酸含量基本无影响,因此确定了泡菜的安全食用期。     

某高校蔬菜供应点蔬菜中亚硝酸盐的测定和分析

近些年来,高校食品安全事故层出不穷,对师生的健康造成极大的威胁。如何保障校园食品安全,是目前高校所面临的重大问题之一。而蔬菜作为高校食堂中最为常见的食材,其农药残留量、亚硝酸盐含量的高低,都会对人体健康产生不同程度的影响。本文为了解高校食堂中蔬菜食品安全的实际情况,选取了西红柿、大白菜、黄瓜、油菜、洋葱、大蒜、土豆、茄子、胡萝卜、黄豆芽等在高校食堂中最为常见的十种蔬菜,对其所含亚硝酸盐含量进行测定,以期为广大师生选择低含量蔬菜提供依据。     

硝酸银中亚硝酸盐含量的分析

研究了采用葛利斯试剂分析高纯硝酸银中微量亚硝酸盐(NO-2)含量的方法,主要讨论了显色剂用量、显色时间等测试条件对测试结果的影响。     

舟山加工海产品中无机砷含量分析及评价

应用氢化物发生-原子荧光法分析了购自舟山南珍菜场和超市的加工海产品中的无机砷。结果显示：超市购买的海产品中无机砷含量普遍较高,其中香烤小黄鱼中含量高达1.52 mg/kg,超出国家规定的限量标准;以含量最高香烤小黄鱼为例,按照海产品50（克/标准人日）的消费量,计算无机砷的摄入量为每人每日76.2μg,没有超出粮农组织/世界卫生组织食品添加剂联合专家委员会（JECFA）规定的每人每日0.129mg的限量,每日食用85g香烤小黄鱼以内不会造成毒性危害。     

深圳周边海域海产品中二十碳五烯酸、二十二碳六烯酸含量分析

分析深圳周边海域常见水产品中EPA、DHA含量。将购买的22种海产品取可食部位,用有机溶剂提取脂肪,甲酯化后的脂肪酸用气相色谱分离分析。结果表明:EPA含量从沙尖鱼的4.38 mg/100 g到秋刀鱼的574 mg/100 g,DHA含量从红三鱼的4.05 mg/100 g到秋刀鱼的881 mg/100 g,EPA+DHA总含量从沙尖鱼的4.38 mg/100 g到秋刀鱼的1455 mg/100 g。不同海产品中EPA、DHA含量存在显著性差异。结论:海产品中EPA、DHA含量因种类不同而存在差异。黄花鱼、海鲈鱼、带鱼、金鲳鱼、秋刀鱼的EPA+DHA总含量较高,每日按推荐量食用,可满足人体对EPA+DHA的需求。     

A/O结合循环式活性污泥法处理海产品加工废水

针对海产品加工废水氨氮含量较高的特点。舟山兴业有限公司的污水处理工程采用两段A/O结合循环式活性污泥法工艺，工程验收合格后运行一年多来，排放废水的各项污染指标均达到国家《污水综合排放标准》（GB8978-1996）的二级标准，处理系统具有很好的抗冲击能力和脱氮效果。     

亚硝酸钙溶液中硝酸根含量的测定

氯化铵法测定亚硝酸钙溶液中硝酸根含量时 ,影响测定结果准确性的因素主要为 :加热微沸时间和诱导反应。消除影响因素后加标回收率达 96 6 0 %以上 ,与成品甲醇法相比具有操作简便、快速的优点 ,可以满足中控分析要求     

Electricity generation from seafood wastewater in a single‐ and dual‐chamber microbial fuel cell with CoTMPP oxygen‐reduction electrocatalyst

BACKGROUND: To make the treatment of seafood wastewater more economical and sustainable, this study aims to examine electricity generation and simultaneous degradation of organic substances from seafood wastewater in single‐chamber (SC) and dual‐chamber (DC) microbial fuel cell (MFC). RESULTS: By supplying the MFCs with seafood wastewater, the maximum power density produced from the SCMFC was higher than that produced from the DCMFC, which is a consequence of the difference in internal resistance of the two systems. The electrochemical reduction of oxygen catalyzed by C/CoTMPP was comparable with that promoted by commercial C/Pt catalyst. The SCMFC achieved higher organic degradation than the DCMFC, which corresponded to less accumulation of volatile fatty acids being decomposed aerobically promoted by the oxygen diffused from the cathode in the absence of the membrane. Owing to electron losses via aerobic decomposition rather than the electricity‐producing pathway, the higher removal efficiency was in line with the low coulombic efficiency. In addition, the DCMFC having a membrane had a more severe pH polarization than the SCMFC without the membrane. CONCLUSIONS: This study provides a conceptual demonstration of sustainable utilization of seafood wastewater while carrying out biological decomposition in an MFC system in an economical manner. Copyright © 2012 Society of Chemical Industry     

乳粉硝酸盐和亚硝酸盐测定的影响因素探讨

采用镉柱还原分光光度法测定亚硝酸盐及硝酸盐,讨论了各种异常或常见问题的解决方案,包括镉柱的处理与维护,还原能力的测定与镉柱的再生,浑浊与沉淀的处理,显色剂与共存离子的影响,空白问题等。结果表明,镉粒粒径0.3~0.8 mm,镉柱高度10~15 cm时,无论采用何种镉粒,只要处理得当,实用活性都达95%以上。     

反硝化细菌降解养殖水体亚硝酸盐的研究

以校内人工湖水为菌种来源,对反硝化细菌进行了富集培养,考察培养温度、投菌量、初始亚硝酸盐氮(NO-2-N)浓度等因素对反硝化细菌降解亚硝酸盐的影响。结果表明,当温度28℃,投菌量为每升水中20 mL反硝化细菌浓缩液,初始亚硝酸盐氮浓度20 mg/L时,亚硝酸盐氮去除率高达97.12%。     

Nitrate and nitrite reduction of a sulphide-rich environment

A sulphide-rich anaerobic sludge acclimated with a molasses wastewater was used to carry out studies on nitrate and nitrite reductions in continuously stirred batch reactors. It was shown that a COD/N-NO_x ratio as high as 65·6 mg mg⁻¹ did not promote dissimilatory reduction of nitrogen oxides to ammonia. Denitrification was characterized by a probable accumulation of gaseous intermediates, nitric oxide (NO) and nitrous oxide (N₂O), by sulphide consumption with concomitant elemental sulphur production and by an increase of the redox potential. In addition, sulphate reducers were completely inhibited by nitrogenous oxides. Cultures performed without any carbon source proved that denitrifiers were able to use sulphides as electron donors. Furthermore, while a lag phase preceded nitrate denitrification, nitrite was consumed immediately. Chemical reduction of nitrite by ferrous iron (Fe²⁺) was considered to be responsible for this difference. Evidence of such a chemodenitrification has been presented by using a sterilized sludge which kept its ability to reduce nitrite while it lost its capacity to use nitrate. Moreover, this chemical activity was favoured by Fe²⁺ addition. Finally, it has been suggested that during the cultures performed with non-sterilized sludge, a biological reduction of the ferric ions (Fe³⁺) would be coupled to nitrite chemodenitrification and would allow a regeneration of Fe²⁺. © 1998 SCI     

硝酸铵生产过程安全技术分析

简要介绍了硝酸铵的各种物理、化学性质以及我国工业上常采用的硝酸铵生产的工艺流程.在此基础上,结合具体生产实际,对生产过程中可能发生的硝酸铵均相分解爆炸的各种影响因素(温度、杂质、物料积聚、热敏感度),以及可能发生危险的其他因素(开、停车,传爆等)进行了详细的安全技术分析,并提出了相应的预防对策.     

微量亚硝酸盐分析方法的研究

碱性桃红T在pH=1的盐酸溶液中可与亚硝酸根生成红色配合物。该配合物在波长为600 nm处有最大吸收,表观摩尔吸光系数为7.38×103L/(mol.cm),亚硝酸盐质量浓度在0μg/mL~3μg/mL,遵守Beer定律,标准偏差1.15×10-3,相对标准偏差0.22%,回收率97%~101%。该法适用于泉水、湖水、河水、污水等水样中亚硝酸盐的分析。     

食品安全性与HACCP

食品安全是当前世界范围内存在的重要问题 ,保证食品的安全对人类健康十分必要。HACCP体系是一种预防性的质量控制体系 ,对建立现代食品安全系统具有重要的指导意义。主要讨论目前食品安全性存在的问题 ,并介绍了HACCP体系在食品安全方面的应用