超声波-中性甲醛浸提-固定pH法快速测定水果中的总酸度

利用超声波一甲醛浸提法从水果中提取酸性物质,通过单因素试验和正交优化试验确定提取的最佳工艺条件.用固定pH滴定法测定水果中的总酸度,以每千克样品消耗KOH标准溶液的物质的量(mol/kg)为计算指标,并与国标方法进行比较,从而为水果总酸度的测定提供了一种全新的分析方法.结果表明:超声波浸提时的料液比、浸提时间,水浴温度对酸性物质的提取效果影响较大.固定功率为500W时,其优化工艺条件为:中性甲醛2.00ml,料液质量比1:16、超声15min,80"C水浴中提取7min.结论:用中性甲醛浸提并转换弱酸为强酸,固定pH8.20滴定水果总酸度,同时规范和统一计算方法,是更为科学、合理的新型分析方法,用于实际样品的测定,结果令人满意.     

甲醛释放量控制新法

美国新奥尔良南部地区研究中心的R.M.雷哈与B.A.K.安德鲁以福尔马林对棉织物中棘手的甲醛含量问题进行了试验。这一方法使甲醛施用后在棉织物中的释放量得到了控制,此后可再将织物进行种种除去甲醛的处理。这一研究成果表明甲醛向空气中、水中以及向别的织物扩散状况的改善已成为可能。试验中对时间、温度、湿度的影响,甲醛     

高浓度甲醛气体的采样与测定

织物在甲醛气相整理中,存在着气相甲醛含量的测定问题。为解决这一科研、生产中的具体问题,在研究甲醛性质的基础上,对汽化器、反应器内甲醛气体含量进行了各种试探性测定,从中得出一种比较简单、实用、快速的冷冻自聚采样测定法来检测甲醛含量。本法对织物气相整理的设备设计、工艺条件的控制具有一定的参考意义。     

一种选择性快速测定果蔬汁饮料中氨基酸氮的分析方法

研究在ｐＨ４．８乙酸盐介质中，氨基酸氮与乙酰丙酮和甲醛试剂显色反应的最佳条件，考察共存物质的影响，得到选择性好，灵敏、快速、准确测定ＡＮ的光度分析新体系，用于水果，蔬菜及果蔬汁饮料的ＡＮ测定，结果与甲醛值法相一致，回收率为９５．７％￣１０３％，相对标准偏差〈５％。     

如何加强对纺织品、服装甲醛的控制和监督

国家质量监督检验检疫总局在2002年8月发布了GB 18401—2001《纺织品甲醛含量的限定》强制性标准。该标准已于2003年1月1日实施。在这标准中严格规定了各类纺织品、服装甲醛的限量。为有效贯彻实施这一标准,切实引导企业安全生产,指导消费者健康消费,我所从2002年开始先后举办多次标准宣贯、培训,并通过报刊、电视进行宣传,同时接受用户的甲醛委托检验和对市场纺织品、服装甲醛含量的监督检验。而对量大、面广的纺织品、服装产品如何有效实施甲醛控制和监督,是企业与监督机构共同面临的问题。根据我所近半年1028批次甲醛委托检验监督检     

关于甲醛鞣制毛皮制品的甲醛挥发性的研究及思考

把已知游离甲醛含量的甲醛鞣制的白色兔毛皮置于四种不同的环境条件下,每隔一段时间对其甲醛含量进行测定。通过对测定结果的分析,对甲醛鞣制的毛皮成品所含的游离甲醛的挥发性进行分析和探讨。结果表明,在光线良好,空气流通顺畅的环境条件下,毛皮成品中游离甲醛的挥发速率大,挥发率高;在相对密闭,甲醛浓度含量过高的环境条件下,毛皮成品会吸附空气中所含的游离甲醛,使得自身的甲醛含量变大。参照这一结果,人们在日常生活中的所用的甲醛鞣制的毛皮制品,不应该一直放在密闭的环境条件下。     

甲醛——最后一根稻革？

继TDS、氮、硫化物、六价铬及中性盐等等之后,立法者对制革业又狠狠地咬了一口,这次是甲醛。 纯然是为了迎合消费者的心理,汽车制造者(Audi)提出革的甲醛含量应小于10ppm。我们将含甲醛500ppm的化妆品敷在脸上,用含甲醛1000ppm的漱口液漱口,而要求坐在甲醛小于10ppm的座垫上,这是一个可笑的决定。但制革者只能采取措施以满足汽车制造者的要求。     

市售猪血块中微量甲醛的新法测定

甲醛对人体的危害越来越引起人们的重视,测定某些食品中微量甲醛的含量对于监督和管理食品市场十分重要。本文提出了一种新的测定方法,即利用微量甲醛对氯酸钾氧化甲基橙这一反应的催化作用,进行甲醛的测定。该方法用于市售猪血块中微量甲醛的测定取得了较满意的结果。     

眼界决定高度，高度引领方向——警惕当前市场上“除醛”中的李鬼现象

前几天一位与我同车离开家居大世界的长者,对目前媒体中宣传的甲醛之害十分恐惧,报怨说这也有甲醛,那也有甲醛,一不留神就会把病买回家。谈醛色变,这种心理障碍将在消费群体中潜移默化,继续漫延。装修热造成居室甲醛超标的问题确实不能忽视。据中国室内装饰协会调查,目前我国城镇装修过的家庭中,80％存在甲醛超标问题。从北京的情况看,甲醛超标已涉及到儿童。在不久前由四家权威检测单位组成检测组。对500户新装修家庭检测结果表明, 发现有361户家庭的儿童房甲醛浓度超出国家标准．占受检总数的72．2％,由此甲醛问题被媒体炒得沸沸扬扬。     

甲醛——最后一根稻草

继TDS、氮、硫化物、六价铬及中性盐等等之后,立法者对制革业又狠狠地咬了一口,这次是甲醛. 纯然是为了迎合消费者的心理,汽车制造者(Audi)提出革的甲醛含量应小于10ppm.我们将含甲醛500ppm的化妆品敷在脸上,用含甲醛1000ppm的漱口液漱口,而要求坐在甲醛小于10ppm的座垫上,这是一个可笑的决定.但制革者只能采取措施以满足汽车制造者的要求.     

Formaldehyde in cultivated mushrooms: a negligible risk for the consumer

Following the detection of formaldehyde in cultivated mushrooms, an evaluation was carried out to assess whether its presence in food poses a risk to public health. Formaldehyde, a carcinogenic chemical, has a broad range of industrial applications and, hence, exposure to formaldehyde is ubiquitous through diverse consumer goods, food, the air, etc. The observed levels of formaldehyde in mushrooms are lower than the levels reported for vegetables, fruit, meat, fish and dairy products. On the basis of available data, a rough estimate of the dietary exposure to formaldehyde was performed. The exposure through the consumption of cultivated mushrooms (approximately 0.19 µg kg^?1 body weight day^?1 on average, consumers only) appeared to be small compared with the total dietary intake of formaldehyde (approximately 99.0 µg kg^?1 body weight day^?1, total population). Based on comparison with toxicological safety limits for chronic exposure and given that formaldehyde is carcinogenic only through inhalation and not by ingestion, it can be concluded that the dietary exposure to formaldehyde is not a cause for concern.     

Determination of formaldehyde in fruit juice based on magnetic strong cation-exchange resin modified with 2,4-dinitrophenylhydrazine

A method was developed using magnetic strong cation-exchange resin modified with 2,4-dinitrophenylhydrazine (DNPH) for the determination of formaldehyde (HCHO) in fruit juice samples. The procedures of extraction and derivatization were carried out in a single step by stirring the resins and diluted fruit juice with water. When the procedures were completed, the resins adsorbing the HCHO-DNPH derivative were easily separated from the sample matrix by an adscititious magnet. The HCHO-DNPH derivative eluted from the resins was directly determined by high-performance liquid chromatography with UV detector at 360 nm. The limit of detection of the proposed method in fruit juice obtained is 6.0 ng mL⁻¹. In this work, the volume of fruit juice was 5 mL and the amount of MSCX resins was 100 mg, and the resins can be reused 10 times. The relative standard deviations of intra-day and inter-day ranging from 3.9% to 6.1% and from 4.2% to 7.0% are obtained, respectively. The recovery of HCHO in the analysis of spiked fruit juice samples is in the range of 85.7-100.4%.     

Origin of low-molecular mass aldehydes as disinfection by-products in beverages

ABSTRACT

A novel, simple and automatic method based on static headspace–gas chromatography–mass spectrometry has been developed to determine 10 low-molecular mass aldehydes that can be found in beverages, coming from the treated water used in their production. These aldehydes are the most frequently found in treated water as water disinfection by-products, so they can be used as indicators of the addition of treated water to beverages. The study covered a large number of fruit juices and soft drinks. The presence of the whole array of analytes is related to the contact with treated water during beverage production, mainly by the addition of treated water as ingredient. In particular, propionaldehyde, valeraldehyde and benzaldehyde can be used as indicators of the addition of treated water in these kinds of beverages. Among the ten aldehydes, only formaldehyde and acetaldehyde are naturally present in all kinds of fruit, and their concentrations are related to stage of the ripening of the fruit.     

Survey of the migration of melamine and formaldehyde from melamine food contact articles available on the UK market

The migration of melamine and formaldehyde, monomers used in the production of melamine-ware food contact articles, has been determined from 50 retail articles purchased in the UK. The food simulant 3% aqueous acetic acid was used as this is the most aggressive simulant towards melamine plastics. The test conditions used were repeated exposure to the simulant for 2 hours at 70°C, since the articles were all intended for general use including contact with hot foods and beverages. Melamine migrated from 43 of the 50 samples tested and formaldehyde migrated from all 50 samples. Directive 2002/72/EC specifies migration limits for both of these monomers in foods and food simulants. Melamine is restricted by a specific migration limit (SML) of 30 mg/kg (equivalent to 5 mg/dm²) and formaldehyde, along with hexamethylenetetramine expressed as formaldehyde, is restricted by a total (T) SML(T) of 15 mg/kg (equivalent to 2.5 mg/dm²). In all cases the migration of melamine was much lower than the SML for this monomer. The migration of formaldehyde exceeded the SML(T) for 5 of the 50 samples tested. The failure to comply with the SML(T) was accompanied by a number of visible surface effects including discolouration and/or pitting of the simulant contact surface and cracking of the articles. Similar surface effects were observed when one of the samples was exposed to fruit juice which confirmed the suitability of the exposure conditions and 3% acetic acid as a simulant for the articles tested. The ratio of specific migration to overall migration was consistent with, but did not prove, the hypothesis that high formaldehyde migration could be due to the use of excessive hexamethylenetetramine in the polymer formulation. All illegal products were voluntarily removed from the market by the product suppliers.     

Endogenous formaldehyde level of foods and its biological significance

 Formaldehyde was measured in different food samples based on its reaction with hydralazine to form s-triazolo-(3,4-α)-phthalazine(Tri-P). Formaldehyde reacts with hydralazine under mild acidic conditions to form Tri-P. The reaction products were separated by reversed-phase, high-performance liquid chromatography. The method of sample preparation and chromatography are reviewed and the analytical method validated. Using the discussed methods we measured formaldehyde levels in 23 animals and 22 vegetable and fruit samples. Formaldehyde levels were one and a half times higher in vegetable samples compared to meat samples. Received: 23 December 1996 / Revised version: 17 March 1997     

不同纺织品甲醛检测标准对比及检测结果回归分析

对不同纺织品甲醛检测标准进行了对比研究,对各标准间差异对甲醛检测结果的影响和各检测结果间的回归性进行了分析。结果表明:水萃取法的GB(ISO)标准与JIS标准(间苯三酚法)间差异较大。蒸汽吸收法的GB(ISO)标准与JIS标准间差异及与AATCC标准间某些差异较大;甲醛检测结果由高到低依次为:AATCC标准释放甲醛、GB(ISO)标准释放甲醛、GB(ISO)标准游离和水解甲醛、JIS标准游离和水解甲醛;不同标准甲醛检测结果间具有十分显著的线性回归关系,且拟合程度很好。     

纺织品甲醛含量测定的影响因素

分析和讨论了甲醛标准溶液的配置时间、配置方法等因素对其吸光度的影响规律;另外还对织物中甲醛的萃取织物质量、试样浸泡的时间、取浸泡液的量等因素做了细致的研究与分析,总结了影响纺织品中甲醛检测的各种因素,对改进甲醛检测方法的研究有一定的参考价值和实用意义.     

皮革中甲醛的产生和控制

分析了游离甲醛对人体和环境的危害以及皮革制品中游离甲醛的限量标准。在概述甲醛性质的基础上,分析了皮革中游离甲醛的来源,并进一步提出了皮革中游离甲醛的解决办法。     

甲醛清除膜清除人造板和家具中游离甲醛的试验研究

针对目前国内室内游离甲醛浓度严重超标的现状，研制开发了一种清除游离甲醛的新材料——甲醛清除膜。在开发过程中，探讨了其清除人造板游离甲醛的持续性，其载药量、放置方法与用量以及人造板的种类等与清除游离甲醛效果的关系，并进行了清除家具中游离甲醛的试验。     

纺织品中游离甲醛问题的探讨

文章重点论述了甲醛的性能以及纺织品中甲醛的来源,纺织品中甲醛含量控制的相关标准和测试方法,同时还介绍和分析了当前纺织品市场上甲醛问题的现状,提醒人们要重视纺织品的安全问题.