加碘盐中碘酸根离子的极谱测定

加碘盐中碘含量测定的标准方法是碘量法。由于碘盐中碘含量低,所得终点颜色变化不明显,滴定误差较大。本文提出了在硼砂介质中,采用示波极谱测定加碘盐中碘酸根离子的含量。方法具有灵敏度高,选择性好,操作简便、快速,测定范围广等优点,通过改变样品称取量和分取溶液体积,可测定加碘盐中碘含量范围为０ ．ｘｍｇ／ｋｇ～１００ｍｇ／ｋｇ。     

加碘盐碘含量测定试剂空白结果的分析

本文使用GB 5009.42-2016《食品安全国家标准食盐指标的测定》和GB/T 13025.7-2012《制盐工业通用试验方法碘的测定》氧化还原滴定法测定加碘盐中碘含量,分析试剂空白的影响因素及其对实验结果的影响。结果表明,两种标准的试剂空白测定方法中,次氯酸钠是影响试剂空白结果的关键因素,会使试剂空白结果偏离其实际结果,进而影响加碘盐碘含量的测定。     

加碘盐中碘化钾含量间接碘量分析法

为解决缺碘影响健康而生产的加碘盐中的碘化钾含量的分析,多年来沿用溴水氧化碘量分析法。由于该法毒性强、操作条件恶劣、不易掌握、对环境污染和影响分析人员身体健康,迫切需要用新法代替。本法采用高锰酸钾氧化间接碘量分析法测定加碘盐中碘化钾含量,具有简便、准确、快速、易于掌握、无毒性、无环境污染和对人体无危害的特点。本法测定碘含量范围在900ppm 以内,方法准确度在±0.88%以内。     

氧化还原滴定法测定液态海藻碘类产品中碘含量

建立氧化还原滴定法测定液态海藻碘类产品中碘含量。实验结果表明,液态海藻碘类产品中的碘化物在酸性介质中,会被次氯酸钠氧化成碘酸根,碘酸根将碘化钾氧化析出单质碘,用硫代硫酸钠溶液滴定,可以定量测定碘含量。这种方法的检出限为0.10 mg/kg,平均回收率为95.5%~103.1%,标准偏差为0.0013~0.0019,变异系数为0.002~0.011。本方法设备简单、精密度和重现性好,用于实际样品的测定可以获得满意的结果。     

对含碘酸钾加碘盐中碘的检测方法的探讨

对含碘酸钾的加碘食盐中碘含量的快速测定的检测方法进行探讨,通过实验得到较为可靠的数据,为快速、准确测定加碘盐中的碘提供依据。     

线性扫描伏安法测定食盐中碘含量

以多壁碳纳米管(MWCNT)修饰玻碳电极为工作电极,研究了碘离子在该修饰电极上的伏安分析特性,建立了测定食盐中碘含量的线性扫描伏安法。在优化实验条件下,氧化峰电流与碘离子浓度在1.0×10-6～1.0×10-3 mol/L范围内呈良好的线性关系,检出限为4.0×10-7 mol/L。对1.0×10-4 mol/L碘化钾溶液平行测定10次的RSD为3.2%。将该方法用于测定加碘食盐中的碘含量,结果满意。     

氢化物发生-原子荧光光谱法测定富硒发芽糙米中的硒含量

对氢化物发生-原子荧光光谱法(HG-AFS)测定富硒发芽糙米硒含量的方法.研究表明:其检出限为0.2μg/L,相对标准偏差RSD为0.94%,平均回收率为99.74%,精密度高、稳定性好、简便快速,适合于富硒发芽糙米中硒的定量分析.通过测定采用不同浓度亚硒酸钠溶液富硒处理的发芽糙米的总硒、有机硒和无机硒含量,确定选择硒浓度为50 mg/L的溶液富硒处理后的发芽糙米品质较好.     

动物脏体中微量硒的测定

研究了猪、牛、羊、鸡四类动物的心脏、肝脏、肺脏中微量硒的测定方法。试样在氧弹中以富氧来进行燃烧灰化,使动物脏体中各种形式存在的硒化物被氧化或分解为硒的氧化物后,用浓碱NaOH吸收燃烧产物和用导管导出装有浓NaOH溶液中予以充分吸收,然后调节溶液的pH值至5～8,再用硒-碘化钾-结晶紫-聚乙烯醇显色体系进行测定硒的含量。硒在盐酸介质中可与I3-离子形成三元络合物,其络合物的最大吸收波长为580nm,硒的含量在0～0.25μg/ml范围内服从比耳定律,运用硫脲作为还原剂,EDTA作为掩敝剂,线性回归方程为C=0.4676A-0.0055,相关系数r为0.9995。通过对方法进行回收率测定,回收率在99.14%～100.79%,方法可用于动物脏体内微量硒的测定。     

大麦苗富硒研究

目的：探讨大麦苗不同富集硒的方法以及不同浓度的亚硒酸钠对大麦苗的生长及富硒量的影响。方法：采用水培法栽培大麦苗;富集硒的方法分别为浸麦富硒法、出苗后富硒法以及全程富硒法;透析袋法分离有机与无机硒;原子荧光光谱法测定富硒大麦苗中的硒含量。结果：浸麦富硒时,当亚硒酸钠浓度低于50mg／L时大麦苗生长旺盛,麦苗出率与生长曲线均高于空白对照组;出苗后富硒,亚硒酸钠为30mg／L时,其生长曲线高于空白对照组,其富硒量最高;全程富硒时,大麦苗出芽率,麦苗出率低,且生长迟缓。结论：出苗后富硒,当亚硒酸钠浓度为30mg／L时,大麦苗生长快,且富硒量最高,全硒含量是空白对照组的4．97倍,有机硒含量是空白对照的8．05倍。此为本实验中最佳富硒方法与最佳富硒浓度。     

富硒双孢蘑菇硒形态分布及其营养品质和抗氧化特性

为了研究硒对双孢蘑菇子实体硒形态分布、营养品质和抗氧化酶活性的影响,通过在栽培实验中添加不同用量Na_2SeO_3的方式培养双孢蘑菇。采用原子荧光光谱法测定富硒双孢蘑菇子实体中的硒含量,分析硒在子实体中的分布情况,并以普通双孢蘑菇为对照,对富硒双孢蘑菇的主要营养成分及抗氧化酶活性进行测定。结果表明,双孢蘑菇子实体中的硒含量与培养料中硒用量呈正相关,蛋白硒含量占有机硒含量的比例约为77%~87%,蛋白质是双孢蘑菇的主要硒载体。硒用量为40 mg/kg时,可溶性蛋白和总糖含量较对照组显著增加;硒用量较高时,可溶性蛋白和总糖含量较对照组显著降低。随着硒用量的增加,总氨基酸含量和丙二醛含量增加,超氧化物歧化酶活性增强,而过氧化氢酶活性较低。本实验研究表明,适宜的硒用量可以提高双孢蘑菇子实体中硒含量,有助于改善其营养品质和生理特性。     

浅谈加碘盐碘含量测定方法中仲裁法的确定

根据对GB／T13025．7—1999次氯酸钠氧化法和GB／T13025．7—91饱和溴水氧化法测定碘盐碘含量方法的比对，建议用GB／T13025．7—91饱和溴水氧化法作为测定碘盐碘含量的仲裁法。     

Formation of iodoacetic acids during cooking: Interaction of iodized table salt with chlorinated drinking water

Iodoacetic and chloroiodoacetic acids were formed when municipal chlorinated tap water was allowed to react with iodized (with potassium iodide) table salt or with potassium iodide itself. Iodoacetic acid was recently shown to be a potent cytotoxic and genotoxic agent. For analysis, samples were extracted with t-amyl methyl ether and converted to the corresponding methyl esters using methanol and sulfuric acid. The concentration of iodoacetic acid was determined by gas chromatography-mass spectrometry (GC-MS) using an authentic standard. The identities of iodoacetic and chloroiodoacetic acids were further confirmed by gas chromatography-high-resolution mass spectrometry (GC-HRMS). Certain influences of sodium hypochlorite and humic acid as well as the concentration of potassium iodide on the yields of these acids were investigated. The concentration of iodoacetic acid in tap water samples boiled with 2 g l^-1 of iodized table salt was found to be in the 1.5 µg l^-1 range, whilst the concentration of chloroiodoacetic acid was estimated to be three to five times lower.     

Effect of collagen preparations used as carriers of potassium iodide on retention of iodine and thiamine during cooking and storage of pork meatballs

The application of collagen preparations as carriers of iodine salts in the production of meat dishes was investigated in this study. Meatballs with addition of collagen fibre or collagen hydrolysate, both impregnated with potassium iodide, were cooked and cold‐ or freezer‐stored. After thermal processing and during storage of meatballs the iodine and thiamine contents were determined and compared to their contents in meatballs to which potassium iodide was introduced using iodized table salt. It has been shown that the application of both collagen preparations as carriers of potassium iodide increases the stability of this compound during cooking and storage of meatballs in comparison to its stability in products with iodized table salt. Collagen preparations, improving potassium iodide stability, also limit thiamine losses in the product. A more advantageous effect, both on iodine and thiamine retention, is achieved for the collagen preparation with a higher water binding capacity. Copyright © 2007 Society of Chemical Industry     

氧化还原间接碘量法测定铁强化营养盐中铁的试验方法研究

在一定酸度（pH〈1）下,EDTA铁钠络合物离解出Fe3＋,加入碘化钾,Fe3＋和IO3-与I-反应生成游离碘,然后用硫代硫酸钠标准溶液滴定,测定铁的含量。根据氧化还原间接碘量法测定铁而进行了条件试验,如酸度试验,碘化钾用量试验,放置时间试验等等。     

Stability of iodine in iodized fresh and aged salt exposed to simulated market conditions

BACKGROUND: The salt iodization law of the Philippines required that iodized salt sold at retail not be exposed to direct sunlight, high temperature and relative humidity, and contamination with moisture and dust from the environment. However, because the majority of local consumers buy salt displayed in open heaps, it was suggested that iodized salt should be sold in the same manner for greater accessibility and availability. Objective. We aimed to provide evidence on the stability of iodine in local aged and fresh salt iodized at 100 ppm iodine and exposed to various market and storage conditions. METHODS: Samples of salt in open heaps and repacked salt were exposed for 4 weeks, and salt packed in woven polypropylene bags was stored for 6 months. The iodine content of the salt was determined by the iodometric titration method, and the moisture content was determined by the oven-drying method. RESULTS: For all types of exposed salt, iodine levels were above 60 ppm after the end of the study (4 weeks). Within each salt type, losses were greater for open-heap salt than for repacked salt. The greatest drop in moisture content occurred in the first week for most types of salt and exposure combinations. Moisture content was linearly correlated with iodine content. Iodine levels in stored salt remained above 60 ppm even after 6 months. CONCLUSIONS: Iodized salt is able to retain iodine above the recommended levels despite exposure to an open environment and use of ordinary packaging materials while being sold at retail and kept in storage.     

Stability of iodine in salt fortified with iodine and iron

BACKGROUND: Determining the stability of iodine in fortified salt can be difficult under certain conditions. Current methods are sometimes unreliable in the presence of iron. OBJECTIVE: To test the new method to more accurately estimate iodine content in double-fortified salt (DFS) fortified with iodine and iron by using orthophosphoric acid instead of sulfuric acid in the titration procedure. METHODS: A double-blind, placebo-controlled study was carried out on DFS and iodized salt produced by the dry-mixing method. DFS and iodized salt were packed and sealed in color-coded, 0.5-kg, low-density polyethylene pouches, and 25 of these pouches were further packed and sealed in color-coded, double-lined, high-density polyethylene bags and transported by road in closed, light-protected containers to the International Council for the Control of Iodine Deficiency Disorders (ICCIDD), Delhi; the National Institute of Nutrition (NIN), Hyderabad; and the Orissa Unit of the National Nutrition Monitoring Bureau (NNMB), Bhubaneswar. The iodine content of DFS and iodized salt stored under normal room conditions in these places was measured by the modified method every month on the same prescribed dates during the first 6 months and also after 15 months. The iodine content of DFS and iodized salt stored under simulated household conditions was also measured in the first 3 months. RESULTS: After the color code was broken at the end of the study, it was found that the DFS and iodized salt stored at Bhubaneswar, Delhi, and Hyderabad retained more or less the same initial iodine content (30-40 ppm) during the first 6 months, and the stability was not affected after 15 months. The proportion of salt samples having more than 30 ppm iodine was 100% in DFS and iodized salt throughout the study period. Daily opening and closing of salt pouches under simulated household conditions did not result in any iodine loss. CONCLUSIONS: The DFS and iodized salt prepared by the dry-mixing method and stored at normal room conditions had excellent iodine stability for more than 1 year.     

长效缓释型微胶囊碘剂的开发与应用

开发了一种新型的加碘剂-微胶囊碘剂,介绍了它的制备原理、方法与特点,具有稳定性好、加工成本低、碘剂使用效率高等优越性。微胶囊碘剂可替代现有加碘剂,用于制盐、食品、饲料等行业,它的推广应用将产生良好的经济与社会效益。     

浅析食用盐中碘剂的应用

主要介绍了我国食用碘盐的发展,并对作为补碘剂的碘化钾、碘酸钾和海藻碘进行比较。     

Adding an oxidant increases the stability of iodine in iodized salt

It has been shown that moisture plays a critical role in the stability of iodine and that reducing agents in iodized salt reduce the stability of iodine. We question whether this is valid in all cases, and have found that the reducing agent may play a more important role than moisture in decreasing the stability of iodine. We reviewed current methods to enhance iodine retention in iodized salt, and propose methods to produce stable iodized salt and to analyze its stability. Our experiments showed that when reducing impurities are removed, iodine remains stable in iodized salt, even when the salt is "wet." We suggest that the stability of iodine in iodized salt can be improved by oxidizing iodized salt with sodium hypochloride, and that the iodine content of iodized salt, after heating at 120 degrees C for one hour, can be used to reflect the quality of iodized salt. We have demonstrated that reducing agents play a critical role in the stability of iodine in iodized salt. We have shown a method of purifying salt by removing reducing materials, which can be used to produce iodized salt with sufficient stability at lower cost. We also propose an analytical method to determine the stability of iodine in iodized salt. These methods could be further developed to achieve better accuracy, precision, and reliability and be applied to a greater variety of iodized salts.     

加碘食盐中碘损失的实验研究(Ⅱ)

采用氯化钠增敏光度法研究了在模拟烹饪条件下加碘食盐中碘的稳定性.实验结果表明,碘盐中碘的稳定性并不理想,加碘食盐中碘的稳定性受温度与受热时间的影响较大,受热温度越高,碘损失越多;受热时间越长,碘损失越多.