柱后衍生-高效液相色谱法测定金针菜中亚硫酸盐

亚硫酸盐包括二氧化硫,有漂白、增白、防褐变及防腐等作用,在食品工业中被广泛使用,因此食品中亚硫酸盐的毒性日益受到关注。人体长期摄入亚硫酸盐会严重损害身体健康。许多国家对食品中的亚硫酸盐含量规定了最大使用量和最大残留限量,并且研究了各种亚硫酸盐的测定方法[1-3]。     

甲醛吸收-盐酸副玫瑰苯胺-分光光度法测定生粉中亚硫酸盐

<正>亚硫酸盐是食品工业广泛使用的漂白剂、防腐剂和抗氧化剂,许多国家允许亚硫酸盐作为食品添加剂使用。合理使用亚硫酸盐可以使食品保持鲜艳色泽,还可以抑制食品中的氧化酶,防止食品褐变,但过量摄入亚硫酸盐会导致头痛、恶心、晕眩、气喘、呕吐等过敏反应[1]。随着研究的不断深入,亚硫酸盐的毒性日益受到人们的关注。目前,食品中二氧化硫的测定方法多参照国家标准GB/T 5009.34-2003[2]中的第一种方法,即     

快速测定食品中二氧化硫残量

通常为了食品的美观需在食品中添加一定量的漂白剂,它可使食品看起来新鲜和洁白,一般这些漂白剂都使用食品级的亚硫酸盐、连二硫酸盐等物质。这些物质加入食品后,易分解成具有漂白作用的二氧化硫,使食品变得洁白。我国在国标2760中对食品中检出的二氧化硫残量有一定的规定。二氧化硫残留量的检验方法常用的有蒸馏滴定法(将二氧化硫从食品中蒸馏出来,然后用碘量法滴定),盐酸副玫瑰苯胺比色法[1](用四氯汞酸钠吸收食品中的二氧化硫,再与盐酸副玫瑰苯胺显色)。这些方法操作较复杂,时间也较长,需要的试剂较多。本文根据活泼金属单质如铁、铝…     

二氧化硫光度分析的研究进展

二氧化硫(SO_2)、亚硫酸盐具有漂白、防腐及抗氧化等功能,是各国广泛使用的食品添加剂,也是大气污染的主要检测物之一。在食品科学、环境科学研究领域中极为重要。近年来在二氧化硫分析方面,发展了多种新的检测方法。如吸光光度法、荧光分析法、离子色谱法、电化学法、顶空气相色谱法及高效液相色谱法等。但光度分析仍是目前检测的主要手段。有关1990年前二氧化硫非汞盐分析现状已有综述,本文针对光度分析的特点,将1990年～1996年12月间发表的二氧化硫在食品、环境试样方面的文献作一概述和讨论。     

离子色谱法测定辛辣食品中的SO32-(SO2)含量

采用阴离子色谱-抑制电导检测器测定姜、蒜、辣椒、芥末、洋葱等带有辛辣气味的含硫食品中的亚硫酸盐(二氧化硫)残留量,采用酸性条件下的水蒸气蒸馏方法对样品进行提取纯化。线性范围为1．0～160．0mg／kg,回收率为80％～110％,满足出口食品检测要求。该方法适用于出口脱水菜和袋装水煮菜中SO3^2-(SO2)的测定。     

热挥发扩散-邻苯二甲醛显色快速测定白芷中二氧化硫残留的研究

采用盐酸介质中热挥发扩散-邻苯二甲醛显色反应-紫外-可见分光光度法测定白芷中二氧化硫残留量。样品中的亚硫酸盐被盐酸转化为二氧化硫,受热挥发,扩散至内反应管,与邻苯二甲醛、乙酸铵溶液反应生成的紫色物质。最佳测定条件下的紫色反应产物在420nm波长下具有较强的紫外-可见吸收,且吸光度与亚硫酸钠加入量成正比。据此建立吸光度与亚硫酸盐含量的标准曲线方程,方程线性相关系数r为0.9935,线性关系较好。该法简便、快速、试剂用量少、不受样品基质干扰,可为白芷二氧化硫残留量的测定提供参考。     

三邻菲咯啉合亚钌-亚硫酸根-过二硫酸钾化学发光法测定空气中的二氧化硫

提出了－菲咯啉）化学发光测定亚硫酸盐的方法。亚硫酸盐的浓度与化学发光强度在1．75×10－7～1．25×10-4mol／L范围内呈正比。检出限为6×10－9mol／L,4×10－5mol／L亚硫酸盐溶液9次测定的相对标准偏差为1．4％。该方法用三乙醇胺作为吸收液成功地测定了空气中的二氧化硫。     

高中新课本“氧族元素”的教学法(二)

第十一课二氧化硫本课目的:使学生瞭解二氧化硫的制法、性质及用途。检查学生知识以後,让学生回忆在氧中或在空气中燃硫产生什麽臭味的气体,然後指导学生在试管中加少许亚硫酸钠及硫酸,注意所产生气体的臭味。再让学生用一小块黄铁矿放在铁片上加热,注意火焰的颜色及臭味。教师作出关于二氧化硫制法的结论:①燃硫②亚硫酸盐加硫酸,③燃烧黄铁矿。当提出每一种制法时,就可指定一学生完成反     

二氧化硫衍生物荧光探针的研究进展

二氧化硫衍生物亚硫酸氢盐和亚硫酸盐在食品的防腐、抗菌和抗氧化等方面起着重要的作用.两种物质的化学和生物分子功能对环境和人类健康的重要性受到广泛关注.定量检测二氧化硫衍生物在生化研究和相关疾病诊断方面有着突出的意义.目前,利用高选择性、高灵敏度的光学探针开展二氧化硫衍生物的检测研究已成为前沿课题之一.其中,荧光探针由于具有简便性、高时空分辨能力等特点尤其受到关注.本文基于光学探针与二氧化硫衍生物的不同反应机理,针对近年来该领域的研究新进展进行了较系统的评述.所涉及的反应机理主要有乙酰丙酮酸酯的加成、醛基加成、其他双键的麦克尔加成、C=N键异构化等.此外,还对检测二氧化硫衍生物的光学探针存在的问题进行了讨论,并在目前研究的基础上对其发展趋势与应用前景进行了展望.     

碳点增敏的流动注射化学发光法测定食品中二氧化硫的含量

二氧化硫的检测对于食品安全保障具有重要意义。采用酸性高锰酸钾-亚硫酸盐化学发光体系,以碳点(Carbon Dots,CDs)为增敏剂,结合流动注射技术(Flow Injection Analysis,FIA)建立了一种用于检测食品中二氧化硫含量的简便方法。在优化的实验条件下,该方法的线性范围为1.0×10^-5–3.0×10^-4 mol·L^-1,检出限为7.79×10^-6 mol·L^-1。该实验适合作为本科生仪器分析课程的教学实验,帮助学生掌握化学发光、流动注射分析技术的原理及应用,学习科学研究的基本方法,提高思考能力。     

Radical terpolymerization of sulfur dioxide,styrene, and methyl methacrylate

The radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate in o-dichlorobenzene with 2,2′-azobisisobutyronitrile was carried out in order to clarify the propagation mechanism of the radical copolymerization of sulfur dioxide and styrene, especially as a function of total concentration of sulfur dioxide and styrene. From the analysis of the trigonal composition diagrams it has been definitely shown that the radical copolymerization of sulfur dioxide and styrene proceeds by the propagation of two monomers, but the usual type of copolymerization mechanism, explicable in terms of the Lewis-Mayo equation, is not applicable to this copolymerization. The participation in the propagation of a monomer charge-transfer complex consisting of sulfur dioxide and styrene was also ruled out.     

催化发光法同时测定空气中的甲醛、苯和二氧化硫

基于甲醛、苯和二氧化硫在纳米Ti3CeY2O11上的催化发光有交叉敏感现象,在3个波长处分别确定甲醛、苯和二氧化硫浓度与催化发光信号强度的响应关系,再依据发光信号强度的叠加性特征即可获取甲醛、苯和二氧化硫的准确浓度,据此建立了同时测定空气中甲醛、苯和二氧化硫的新方法.3个分析波长分别为420、535和680 nm,敏感材料表面温度为280℃,载气流速为130 mL/min.本方法对甲醛、苯和二氧化硫的检出限(3σ)分别为0.04、0.05和0.10 mg/m3,线性范围分别为0.08~75.60 mg/m3、0.10~101.40 mg/m3和0.30~115.00 mg/m3, 回收率分别为96.4%~103.7%、97.8%~102.5%和97.2%~103.3%.常见共存物,如乙醛、甲苯、硫化氢、氨、甲醇、乙醇和二氧化碳等不干扰测定.连续200 h通浓度均为50 mg/m3的甲醛、苯和二氧化硫混合气体,发光强度的相对偏差≤2%,表明此纳米级复合氧化物对甲醛、苯和二氧化硫的敏感性的寿命长.本方法充分利用了交叉敏感现象,可以实现空气中甲醛、苯和二氧化硫的在线分析.     

Chemistry of ascorbic acid and sulfur dioxide as an antioxidant system relevant to white wine

The impact of the combined ascorbic acid and sulfur dioxide antioxidants on white wine oxidation processes was investigated using a range of analytical techniques, including flow injection analysis for free and total sulfur dioxide and two chromatographic methods for ascorbic acid, its oxidative degradation products and phenolic compounds. The combination of different analytical techniques provided a fast and simultaneous means for the monitoring of oxidation processes in a model wine system. In addition, the initial mole ratio of sulfur dioxide to ascorbic acid was varied and the model wine complexity was increased by the inclusion of metal ions (copper(II) and iron(II)). Sulfur dioxide was found not to be a significant binder of ascorbic acid oxidative degradation products and could not prevent the formation of certain phenolic pigment precursors. The results provide a detailed insight into the ascorbic acid/sulfur dioxide antioxidant system in wine conditions.     

Simple spectrophotometric and titrimetric methods for the determination of sulfur dioxide.

The proposed work describes a simple spectrophotmetric as well as a titrimetric method to determine sulfur dioxide. The spectrophotometric method is based on a redox reaction between sulfur dioxide and iodine monochloride obtained from iodine with chloramine-T in acetic acid. The reagent iodine monochloride oxidizes sulfur dioxide to sulfate, thereby reducing itself to iodine. Thus liberated iodine will also oxidize sulfur dioxide and reduce itself to iodide. The obtained iodide is expected to combine with iodine to form a brown-colored homoatomictriiodide anion (460 nm), which forms an ion-pair with the sulfonamide cation, providing exceptional color stability to the system under an acidic condition, and is quantitatively relatd to sulfur dioxide. The system obeys Beer's law in the range 5 - 100 microg of sulfur dioxide in a final volume of 10 ml. The molar absorptivity is 5.03 x 10(3) l mol(-1)cm(-1), with a relative standard deviation of 3.2% for 50 microg of sulfur dioxide (n = 10). In the titrimetric method, the reagent iodine monochloride was reduced with potassium iodide (10%) to iodine, which oxidized sulfur dioxide to sulfate, and excess iodine was determined with a thiosulfate solution. The volume difference of thiosulfate with the reagent and with the sulfur dioxide determined the sulfur dioxide. Reproducible and accurate results were obtained in the range of 0.1 - 1.5 mg of sulfur dioxide with a relative standard deviation of 1.2% for 0.8 mg of sulfur dioxide (n = 10).     

离子色谱法测定气体中痕量二氧化硫

建立了测定气体中痕量二氧化硫的离子色谱法。采用氢氧化钠–过氧化氢溶液为吸收液,将气体样品中痕量二氧化硫转化为硫酸根离子,以离子色谱法测定硫酸根离子,从而得到气体中二氧化硫含量。二氧化硫气体含量在1~100μL/L范围内与色谱峰面积线性关系良好,相关系数为0.999 9。二氧化硫的检出限为0.1μg/L,测量结果的重复性小于2%(n=6),测定标准样品的回收率在98.1%~99.6%之间,准确度优于对照方法。     

Effect of ultraviolet irradiation on terpolymerization of sulfur dioxide with two unsaturated compounds

The terpolymerization of sulfur dioxide, butene-1 and acrylonitrile affords terpolymers containing equimolar amounts of sulfur dioxide and butene-1 with various acrylonitrile contents. Ultraviolet irradiation was found to accelerate the polymerization and decrease the acrylonitrile content in the polymer. This fact is interpreted by a mechanism through a copolymerization of sulfur dioxide–butene-1 complex and acrylonitrile, whereby the polymerizability of sulfur dioxide–butene-1 complexed monomer may be accelerated by ultraviolet light. In fact, a binary system of sulfur dioxide and butene-1 was found to be accelerated by ultraviolet irradiation, and it affords a maximum rate at a 1:1 composition of feed monomer. Ultraviolet light of 250–300 mμ wavelength is effective for the initiation and the propagation. This may be ascribed to the ultraviolet absorption of the sulfur dioxide–butene-1 complex. The temperature coefficient was measured in both dark and ultraviolet irradiation reactions. The ultraviolet irradiation enhances the reactivity of sulfur dioxide–butene-1 complexed monomer at low temperature. In the terpolymerization with sulfur dioxide, isoprene, and butadiene, the ratio of isoprene and butadiene in the terpolymer was not altered by ultraviolet irradiation because both monomers from complexes with sulfur dioxide, perhaps having the same temperature coefficient for the polymerization.     

低浓度氮中二氧化硫气体标准物质的制备

以二氧化硫纯度标准物质和高纯氮气为原料,采用与一级标准物质比较法制备了摩尔分数为10~100μmol/mol的氮中二氧化硫标准物质。用二氧化硫分析仪对配制的标准物质进行了机械混匀试验、压力均匀性和时间稳定性试验。结果表明,滚动30~80 min后该标准物质机械混匀良好;经F检验,在10~0.5 MPa范围内该标准物质量随压力变化无显著差异,具有较好的压力均匀性;在–20℃和40℃条件下保存7 d,其量值无显著变化,可满足运输环节量值稳定性要求;在常温下贮存11个月,量值无显著性变化,满足国家二级标准物质稳定性要求。采用与一级标准物质比较法定值,并对定值结果的不确定度进行了评定。研制的低浓度氮中二氧化硫气体标准物质的标准值分别为9.89,55.4,101.2μmol/mol(U_(rel)=2%,k=2),该标准物质满足国家二级标准物质的相关技术要求,可用于仪器校准、测量过程质量控制及分析方法的确认和评价。     

Determination of traces of sulfur in selenium by molecular emission cavity analysis

The selenium sample (ca. 1 mg) containing 40–90 μg g^-1 sulfur is decomposed in a combustion apparatus and the evolved sulfur dioxide is adsorbed on about 30 mg of silica gel. The silica gel is deposited in a cavity and the sulfur is determined by molecular emission cavity analysis. Incomplete sulfur recoveries (86 ± 4%) caused by incomplete conversion to sulfur dioxide necessitate a correction factor.     

烟气中二氧化硫及三氧化硫测定方法的研究

本文采用过氧化氢-氯化钡-钍试剂法以及80%异丙醇-氯化钡-钍试剂法分别测定了烟气中的二氧化硫及三氧化硫质量浓度,并对该方法的灵敏度、准确度以及各种影响因素进行了研究分析.本方法简单、快速、准确、便于现场监测控制.     

Photocatalytic Reaction of Sulfur Dioxide with Heptane in the Gas-phase Over Titanium Dioxide

IntroductionA broad range of orgainc compounds[1 ,2 ]can be oxidized by means of semiconductor pho-tocatalysis with a primary focus on Ti O2 as a durable photocatalyst in recent years.WhenTi O2 is illuminated with the light of energy greater than the semiconductor band gap,elec-tron- hole pairs(e-- h ) are formed in the conduction and thevalence bandsof thesemiconduc-tor,respectively.These charge carriers,which migrate to the semiconductor surface,are ca-pable of activating oxygen species,et…