电感耦合等离子体质谱-离子色谱法检测食盐中的碘

1 引言 碘摄入量不足或过量摄入,对人体健康都存在负面影响.因此,准确测定加碘盐中碘的含量对保证加碘盐的质量非常重要.由于食盐的主成分为氯化钠,其对碘的检测产生干扰,所以碘盐中碘的分析一直受到关注.目前,盐碘的测定主要有容量法和催化动力学法、气相色谱法等.市场上出售的加碘食盐主要是添加碘酸钾.本实验采用离子色谱仪(IC)-电感耦合等离子质谱仪(ICPMS)联机对加碘盐中碘的形态进行分析,与离子色谱安培检测法相比,检测结果均相吻合.本方法简单快捷、检出限低、回收率好.     

离子色谱法分析加碘食盐中的微量碘

研究了离子色谱法分析加碘食盐中的微量碘的分析方法。用硫化钠将加碘盐中的碘酸根还原成碘离子，用乙醇提取碘离子，用较高浓度的碳酸钠－碳酸氢钠淋洗液；紫外检测波长２１５ｎｍ；碘的回收率在９６．１％￣９９．８％之间，方法简便，快速。     

高碘甲状腺病:一个不容忽视的公共卫生问题

我国基本实现消除碘缺乏病阶段目标后,全民食盐加碘带来的负面影响已成为目前不容忽视的公共卫生问题。从临床病理资料统计、流行病学调查和全国监测数据分析3个方面论述了全民食盐加碘后出现高碘甲状腺病的证据及严重性。     

重庆地区食盐加碘含量下调的可行性研究

为探讨重庆市食盐加碘含量下调的可行性,分析比较了重庆市碘盐和碘缺乏病监测结果(儿童甲状腺肿大率、智商、尿碘、家庭食用碘盐)。结果表明,碘盐含量稳定,全民食盐加碘防治碘缺乏病的措施成功,但尿碘水平高于适宜水平,甲肿率居高不下,可能存在补碘过量,引起高碘性甲状腺肿大。为有效控制甲肿率和尿碘水平,建议下调食盐加碘含量。     

淀粉作显色剂吸光光度法测食盐中碘酸钾

碘是人类必需的营养素。它是甲状腺激素的重要组成部分,该激素在促进人体的生长发育,维持机体正常的生理功能等方面起着十分重要的作用。人体中缺碘时,会引起甲状腺肿和地方性克汀病,缺碘母亲生的小孩可患呆小病。碘缺乏症多是地区性的,可以通过富含碘的食物或加碘食盐来治疗。因此,食物中碘的测定在营养学上具有重要意义。目前,为防止人类缺碘,普遍食用加碘食盐。食盐中的碘是以碘酸钾形式存在,测定碘的方法有氯仿萃取比色法.     

均三溴偶氮胂褪色分光光度法测定食盐中碘

食用加碘食盐是消除碘缺乏病的主要有效手段,食盐中碘的测定方法很多,本文采用在硝酸介质中以溴化钾为催化剂,碘酸钾氧化均三溴偶氮胂使其褪色,建立了测定碘的方法。     

流动注射-催化分光光度法测定加碘食盐中的无机总碘

根据碘酸根离子（或其它氧化态的碘）在酸性介质中先经亚砷酸还原成碘离子,再利用碘离子催化Ｃｅ（Ⅳ）－Ａｓ（Ⅲ）反应可测定碘酸根离子（或其它氧化态碘）的原理,建立了流动注射催化分光光度法测定碘酸钾或碘化钾加碘食盐中无机总碘的新方法,该法质量浓度的线性范围为０～０．５０ｍｇ／Ｌ,适合于上述两种加碘食盐１００倍稀释液的测定,质量浓度的检出限为０．０３ｍｇ／Ｌ（对应于固体食盐３μｇ／ｇ的Ｉ）。对于０．３０ｍ     

一个课外化学探究实验的设计——食用加碘盐的简易识别方法

设计了一种能够在家庭条件下实现的检查食盐是否含碘的简易识别方法——KI-淀粉试纸法。食盐中的碘以碘酸钾形式存在, 利用碘酸根的氧化性及碘离子的还原性, 2者在酸性条件下生成碘单质, 遇淀粉变蓝来鉴定。此KI-淀粉试纸法也可以帮助消费者在家庭条件下对食盐中是否含碘进行检验, 为市民吃上合格的加碘食盐提供了一种简易识别方法。     

加碘食盐中微量碘的离子选择性电极测定

在加碘食盐中加入还原剂将KIO3中的IO3^-还原为I^-,使用碘离子选择性电极技术,采用标准曲线法直接测定了溶液中的I-量.并引入表面活性剂作为增敏剂,降低了检测下限,提高了检测的灵敏度.实际测定3种食盐样品,取得了较好的效果.     

Excel在理化检验中的应用

对食用盐中碘和盐业部门的加碘食盐 (根据调查加碘食盐中碘均以碘酸钾形式加入 )中的碘含量进行监测时 ,由于此项工作样本量多 ,为了避免人为误差 ,可运用Ｅｘｃｅｌ电子表格的数据处理功能 ,对测定的大量数据进行统计计算 ,提高其准确度。1　原理碘盐中的碘酸钾在酸性环境中 ,加入过量的碘化钾析出碘 ,以淀粉作指示剂 ,用硫代硫酸钠标准溶液滴定并计算其含量 :ＩＯ- 3+ 5Ｉ- + 6Ｈ+3Ｉ2 + 3Ｈ2 Ｏ　　　2Ｎａ2 Ｓ2 Ｏ3+Ｉ2 2ＮａＩ+Ｎａ2 Ｓ4 Ｏ62　食盐中碘含量检测称取碘盐 10 .0 0 0 0 ｇ置于 2 5 0ｍｌ碘量瓶中 ,加无碘水 5 0ｍｌ使盐…     

Interaction of iodine species with glycogen at high concentrations of iodine

Glycogen–iodine (GI) complex formation has been studied at different concentrations of iodine and glycogen. For each glycogen concentration (0.25, 0.125, 0.0625, 0.0313 g/L), the iodine concentration was varied from 0.0317 to 1.59 g/L and the absorbance readings were taken at 453 and 560 nm (GI wavelengths of maximum absorbance). The 453 nm absorbance curves for the GI solution (GI complex and unreacted iodine), and that of the pure iodine solution (without glycogen) level off at a high iodine concentration, and give a peak in the subtracted curve. The 560 nm curves consistently increase in absorbance, and no peak is noticed in the subtracted curve. The spectra of concentrated iodine solutions in water and alcohol suggest the formation of neutral iodine clusters. We suggest that these iodine clusters do not react with glycogen, and that the GI complex formation takes place by the addition of I₂ molecules. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 927–931, 1997     

碘化法提金工艺中碘及碘离子连续测定研究

建立了一种碘化法提金液中碘及碘离子的连续测定方法,调节溶液酸度,用硫代硫酸钠滴定溶液中碘,在滴定完碘的溶液中,以曙红为指示剂,以硝酸银定量滴定溶液中的碘离子,扣除碘生成的碘离子即可得到溶液中的碘离子。采用定量模拟碘化法提金液验证方法的有效性,同时进行加标回收及精密度实验,加标回收率为98.1%~103%,相对标准偏差(RSD,n=10)在0.19%~0.67%,方法精密度好,可满足碘化提金液中碘及碘离子的分析测定。     

煤中碘的淋滤行为研究

用不同pH值溶液对煤进行动态淋滤实验,用电感耦合等离子体质谱(ICP-MS)测定不同pH值淋滤液在不同时间段获取的淋出液中碘的浓度,以及煤和淋滤后残留煤的高温热水解溶液中碘的含量。结果表明,淋滤液pH值、淋滤时间、煤中碘的赋存形态及在煤中的赋存部位对碘的淋出有重要影响。淋滤液的酸性越强,煤中碘的淋出越多,pH值为2.0和pH值为4.0溶液对煤中碘的淋出率(η)分别为7.22%和6.20%;但pH值为2.0溶液的淋出液中碘的量小于pH值为4.0溶液的淋出液中碘的量,其百分率(w_x)分别为1.920 0%和5.420 0%。pH 2.0淋滤液,在前30 h内淋出液中碘的平均浓度为10.9 μg/L;而pH值为4.0淋滤液,在前110 h内淋出液中碘的平均浓度为10.6 μg/L;pH值为6.0和pH值为7.5溶液能淋出煤中碘很少。在酸性溶液作用下,首先被淋出的碘是存在煤颗粒表面少量的水溶态和离子交换态碘及大部分碳酸盐态和铁锰氧化物结合态碘,然后煤基质内部的部分水溶态和离子交换态碘及少量的碳酸盐结合态及铁锰氧化物结合态碘等才被淋出。     

Iodine binding by amylopectin and stability of the amylopectin–iodine complex

The iodine binding capacity (IBC) of amylopectin (AP, from potatoes) is determined to be around 0.38% (w/w) of the total AP in the solution. The mass of iodine bound comprises about 13.6% of the mass of AP involved with the complex, suggesting that with every four iodine atoms bound there are 23 anhydroglucose residues (AGU). Since our previous study indicates that four iodine atoms within the helix of 11 AGUs form a chromophore unit in the API complex, only 48% of the AGUs (11 out of 23) in the AP molecule are directly involved with the iodine. The heat of reaction for the API complex formation is determined to be around ?47 kJ/mol of I–I units bound and is significantly lower in magnitude than that of the amylose-iodine (AI) complex [Biopolymers, 31 , 57 (1991)]. A possible mechanism has been proposed for the formation of AI and API complexes with fixed compositions. © 1994 John Wiley & Sons, Inc.     

Iodine binding capacity and iodine binding energy of glycogen

The iodine binding capacity (IBC) of glycogen is around 0.30% (w/w) at 3°C. The amount of iodine complexed comprises about 12.5% of the mass of glycogen that takes part in the glycogen–iodine (GI) complex formation. This suggests involvement of four iodine atoms for every 25 anhydroglucose units (AGU, C₆H₁₀O₅). Since the chromophore is due to the I₄ unit within the helix of 11 AGUs, only 44% of the AGUs (11 out of 25) are involved in the complex formation. The heat of formation of the GI complex is around −40 kJ/mol of I₂ bonded. These results suggest remarkable similarities with those of the amylopectin–iodine (API) complex. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1409–1412, 1997     

Mechanism of positive iodine reactions: Kinetics of oxidation of semicarbazide by iodamine-T, iodine monochloride and iodine

Kinetics of oxidation of semicarbazide (SC) by iodamine-T (IAT), iodine monochloride and aqueous iodine has been studied in aqueous perchloric acid medium. The rate laws followed by the oxidation of SC were determined. The rates decreased slightly with increase in ionic strength of the medium in IAT and ICI oxidations, while the reverse trend was observed with I₂. Decrease in dielectric constant of the medium increased the rates with IAT and ICI, while it decreased the rate in I₂ oxidations. Addition of the reduced product,p-toluene-sulphonamide had no effect on the rate with IAT. Addition of I⁻ had slight negative and positive effects on the rates of oxidations with IAT and ICI, respectively, but the negative effect was considerable in I₂ oxidations. Mechanisms consistent with the observed rate laws have been proposed and discussed. Rate determining steps have been identified and their coefficients calculated. These constants were used to predict the rate constants from the deduced rate laws as [SC], [H⁺] and [I⁻] varied. Reasonable agreement between the calculated constants and experimental values provide support for the suggested mechanisms.     

无烟煤中碘燃烧释放和转化行为研究

采用逐级化学提取法研究无烟煤及其不同温度燃烧产物中碘的各种赋存状态;以小型管式炉模拟煤燃烧装置,考察了加热温度、加热时间、O_2流量以及通入水蒸气对无烟煤中不同形态碘燃烧释放影响及其机理。结果表明,无烟煤中碘主要以有机结合态、铁锰氧化物结合态和水溶态形式存在。加热温度对碘释放和转化有明显影响,碘释放率随温度升高而增加,500-900℃是碘释放的主要阶段。其中,700℃以前,水溶态、离子交换态和有机结合态碘大部分释放,小部分转化为碳酸盐结合态、铁锰氧化物结合态和残留态碘;铁锰氧化物结合态碘主要在700-900℃释放,部分残留态碘在1 100℃前也可释放。无烟煤中碘释放率随燃烧时间延长和O_2流量增大而增大,水蒸气的参与能明显促进碘的释放。在1 100℃、通入水蒸气、O_2流量120 m L/min、燃烧20 min时,93.8%-95.9%碘主要以HI和I_2释放。     

Determining the chromophore in the amylopectin–iodine complex by theoretical and experimental studies

A partial hydrolysis of amylose followed by the addition of iodine provides a spectrum almost identical to that of the amylopectin–iodine (API) complex suggesting the involvement of smaller “amylose-like” units in the API complex. Our theoretical studies on different polyiodine and polyiodide species suggest that a nearly linear I₄ unit stabilized within the cavity of a small “amylose-like” helix is responsible for the characteristic API spectrum. Since there are 2.75 anhydroglucose residues (AGU) for every iodine atom in the amylose–iodine (AI) complex and a structural similarity exists between the API and the AI (amylose–iodine) complexes, we identify (C₆H₁₀O₅)₁₁I₄ to be the chromophore in the API complex. © 1994 John Wiley & Sons, Inc.     

Kinetics of the autooxidation of iodine with regard to the bray-liebhafsky oscillatory reaction

The kinetics of autooxidation of iodine in acidic solutions has been studied and its autocatalytic character has been observed. The proposed reaction scheme, based on the experimental results, is in accordance with the Treindl-Noyes skeleton mechanism for the Bray-Liebhafsky oscillatory reaction.