燃烧氧化-非分散红外吸收法测定饮用水中总有机碳

总有机碳(TOC)和高锰酸盐指数(CODMn)均是衡量水质中有机物相对含量的一项重要指标.在采用高锰酸钾法测定化学需氧量时,只能对水质中的有机物产生部分氧化作用,氧化率为50%左右,并且一些无机还原性物质也参与反应,因此高锰酸盐指数不能完全反应水质中有机物的污染程度.而总有机碳(TOC)的测定采用燃烧法,能将有机物全部氧化,并且具有快速、简单、准确的特点,因此利用TOC指标来表示饮用水中有机物的污染程度是可行的.为此我们进行了实验研究,结果报告如下.     

非分散红外法测定水中总有机碳

近年来关于饮用水中有机物与健康的关系，得到了全球同行的关注。随着分析技术的提高，饮用水中已经检测出大量的有机物质，其中一些物质被毒理学实验和人群流行病学研究判定为对人体有害，甚至有的物质对人体或动物具有致癌性，因此开展水中有机物监测显得越来越重要。     

管材管件浸泡液中总有机碳测定方法的探讨

输配水管材管件种类繁多,目前常见的有硬聚氯乙烯（PVC—U）管材、聚丙烯（PP—R）管材、聚乙烯（PE）管材、聚甲醛（POM）管材以及铝塑复合压力管、玻璃钢等。由于这些产品原料、添加剂和制造工艺的不同,在使用过程中会产生一些化学物质对水质产生影响。该类产品浸泡液中的总有机碳（TOC）,它反映了产品溶解于水中的有机污染物的含量。为此《生活饮用水输配水设备及防护材料卫生安全评价规范》中规定了TOC为管材浸泡试验的增测项目,其卫生要求为：增加量≤1mg／L。本文采用TOC分析仪,湿氧化法测定了多种输配水管材浸泡水中总有机碳的含量,现报告如下。     

总有机碳／总氮分析仪特点

multiN／C3000遵循相关的德国标准，欧洲标准，美国标准和众多的国际标准，如：DIN EN1484，ISO8245，EPA415，ASTM D2579-85，DIN 38409．DIN V ENV 12260等。     

河南省城市饮水系统中总有机碳含量分析

为了解河南省饮用水水源及其经常规处理、输配过程中总有机碳(TOC)的污染状况,于2007年7月,采集洛阳、信阳、周口、开封、安阳和郑州6地市18家水厂的水源水、出厂水和末梢水水样进行TOC含量的测定。结果显示,以地表水为水源的水源水、出厂水、末梢水中TOC平均含量分别为(2.19±1.03)、(1.59±0.99)、(2.37±1.34)mg/L,各环节水样检出率均为100%。以地下水为水源水的水源水、出厂水、末梢水中TOC平均含量分别为(0.18±0.19)、(0.20±0.27)、(0.92±1.32)mg/L,低于以地表水为水源的水源水、出厂水、末梢水,差异均有统计学意义(P0.05);检出率分别为67%,44%,78%。18家水厂中,出厂水中TOC含量降低的有14家,末梢水中TOC含量增加的有13家。提示选择地下水为水源水,合适的常规处理工艺和保持输配管道的清洁可以降低饮水中TOC含量。     

水中总有机碳去除要求及其测定方法比较

１总有机碳（ＴＯＣ）去除要求 １９９８年１２月美国环保局公布消毒剂／消毒副产物规定（Ｉ阶段）。以地面水或直接受地面水影响的地下水为水源的公共供水系统应通过强化混凝或强化软化达到去除消毒副产物前体一总有机碳的要求（表 １）［１］ 去除率由水源水的总有机碳浓度和处理水的总有机碳浓度算出。个别水厂因特定条件,总有机碳的去除要求可按变通办法（从略）。２三种总有机联测定方法比较 Ｋａｐｌａｎ将所有水样过滤去除颗粒物后,测定溶解性有机碳（ＤＯＣ）,从而比较湿化学氧化、紫外－催化和高温－燃烧三种总有机碳测定方法的…     

总有机碳分析仪测定高氯水样的探讨

目的：通过总有机碳分析仪测定高氯水样TOC的探讨。方法：与CODCr进行比较分析。结果：TOC精密度好,准确度高。结论：TOC更能够全面准确地反应污水中有机污染程度,但TOC由于受进样方式的条件限制,测定的TOC不包括全部颗粒态的TOC。     

高频红外碳硫仪检测植物样中的总碳

高频红外碳硫分析仪基于高频感应原理和助熔剂,保证充足的氧气供应,使样品充分燃烧,将样品中含有的碳元素全部转换为二氧化碳,借助吸收特定波长的红外光能量原理将二氧化碳的含量浓度信号转换成电压信号,借助于软件分析得到二氧化碳的准确含量,从而得出样品中碳元素的含量。     

武汉市市政供水系统中总有机碳测定的应用

目的：总有机碳（TOC）相对于化学耗氧量（COD）能更全面的反应水体中有机物的污染程度,且TOC测定操作更简单,数据更准确。方法：分别测定水体的TOC和COD,通过回归方程计算COD的理论值,利用统计方法分析测定结果。结果：水体中的总有机碳和化学耗氧量存在良好的相关性,相关系数在0.7以上,且化学耗氧量的理论值与实测值不存在显著差异。结论：该研究为TOC代替COD提供了实践依据,总有机碳的测定将得到更加广泛的应用。     

雨水中总有机碳含量调查及去除方法初步探讨

雨水是我省沿海农村居民家庭的主要饮用水源之一。为保证居民饮用雨水的卫生质量,对饮用雨水地区的雨水中总有机碳含量进行了检测。在浙江省慈溪市郊区（居民以雨水为主要饮水水源）,选择雨水的收集方式、集雨面积、贮水池容积、水池的材质、雨水的贮存时间及使用方式等基本情况相似的用户,采取随机抽样的方法,抽取常年饮用雨水的当地居民１０户,在丰水期和枯水期（７月和１２月）采集水样,测定雨水总有机碳含量,同时采用自身对照的方法,开展雨水水质有机碳去除试验,对处理前后的水样分别进行总有机碳含量检测。结果发现,抽检的水样全部检出了总有机碳（ＴＯＣ）,ＴＯＣ的含量水平在２．１６～５．２７ｍｇ／Ｌ,总有机碳去除试验结果,去除率１０．７％～１４．２％,提示雨水中总有机碳含量已经达到了一定的丰度,并且较难以去除。     

ICP-AES法和NDIR法测定水中总有机碳的比对研究

目的:对ICP-AES法和NDIR法测定水中总有机碳进行比对研究。方法:分别采用ICP-AES法和NDIR法对方法的灵敏度、准确度、精密度、分析速度进行综合比对研究。结果:ICP-AES法的检出限为0.6 mg/L(以C计),NDIR法的检出限为0.1 mg/L(以C计);两种方法的线型回归系数均为0.999,两种方法的精密度RSD均<2%,两种方法测定总有机碳标准物质结果均在标示值范围内,两种方法均准确可靠;两种方法对一组样品进行配对测试,结果经t检验分析,无显著性差异。结论:ICP-AES法和NDIR法分析性能基本一致,均满足水中总有机碳含量的测定,ICP-AES法分析速度快于NDIR法,更加适宜批量样品分析。     

H2O2低温等离子灭菌循环取消原因分析与对策

目的 分析H2O2低温等离子灭菌循环取消的原因,探讨相应的改进措施.方法 统计本院2007年1月至2011年10月使用H2O2低温等离子灭菌设备的使用情况,分析循环取消的原因及改进对策.结果 共灭菌1104锅次,循环取消49锅次,成功1054锅次,空锅灭菌1锅次.屏幕显示取消原因为“无法清空箱体”30锅次,显示“H2O2浓度过低”11锅次,显示“电源故障”8锅次.结论 多种因素均能影响H2O2低温等离子灭菌的成功率,重视细节的处理如灭菌物品的干燥、彻底清洁、放置平衡等,能有效提高H2O2低温等离子灭菌成功率.     

Evaluation of vaporized hydrogen peroxide, Citrox and pH neutral Ecasol for decontamination of an enclosed area: a pilot study

Hydrogen peroxide, Ecasol and Citrox aerosols were each tested for their ability to kill a range of nosocomial pathogens. Hydrogen peroxide had the broadest microbicidal activity but operational issues limit its use. Ecasol was effective against all micro-organisms, except Clostridium difficile, while Citrox aerosols were not effective against Gram-negative bacilli.     

Effects of hydrogen peroxide treatment on thiol contents in fresh-cut asparagus (Asparagus officinalis) spears

In this work, the impact of hydrogen peroxide (H₂O₂) was investigated on the thiol content of asparagus. Fresh-cut asparagus was treated with H₂O₂ at varied oxidant concentrations and contact times. A significant decrease (α=0.05) was observed in N-acetylcysteine levels treated with 2.5% H₂O₂ for 10 min and with 5% H₂O₂ for 3, 5 and 10 min. Captopril and cysteine levels significantly decreased (α=0.05) in all and most treatment conditions, respectively. Glutathione levels only significantly decreased with 2.5% and 5% H₂O₂ for 10 min treatment. In order to determine whether asparagus undergoes oxidative stress, a well-known oxidative stress indicator—the glutathione/oxidized glutathione ratio—was calculated. This study showed that the common use of H₂O₂ as a disinfectant/sterilizer by the food industry could markedly diminish the important biothiols and develop oxidative stress in asparagus, and potentially in other vegetables as well.     

Evaluation of the biological efficacy of hydrogen peroxide vapour decontamination in wards of an Australian hospital

This study assessed the efficacy of a 'dry' hydrogen peroxide vapour decontamination in an Australian hospital via a two-armed study. The in?vivo arm examined the baseline bacterial counts in high-touch zones within wards and evaluated the efficacy of cleaning with a neutral detergent followed by either hydrogen peroxide vapour decontamination, or a manual terminal clean with bleach or Det-Sol 500. The in?vitro arm examined the efficacy of hydrogen peroxide vapour decontamination on a variety of different surfaces commonly found in the wards of an Australian hospital, deliberately seeded with a known concentration of vancomycin-resistant enterococci (VRE). All bacterial counts were evaluated by a protocol of contact plate method. In the in?vivo arm, 33.3% of the high-touch areas assessed had aerobic bacterial count below the detection limit (i.e. no bacteria recoverable) post hydrogen peroxide decontamination, and in all circumstances the highest microbial density was ≤3?cfu/cm(2), while in the in?vitro arm there was at least a reduction in bacterial load by a factor of 10 at all surfaces investigated. These results showed that dry hydrogen peroxide vapour room decontamination is highly effective on a range of surfaces, although the cleanliness data obtained by these methods cannot be easily compared among the different surfaces as recovery of organisms is affected by the nature of the surface.     

单细胞凝胶电泳法分析指标及检测DNA交联的标准断裂剂的研究

目的 寻求单细胞凝胶电泳计算机成像与分析系统中的有效分析指标，为Ｈ２Ｏ２在１℃条件下作为检测ＤＮＡ交联的标准ＤＮＡ断裂剂提供依据。方法 常规培养Ｖｅｒｏ细胞 悬浮在ＰＢＳ中，Ｈ２Ｏ２染毒，分别在３７℃和１℃条件下孵育１ｈ，常规单细胞凝胶电泳，专用软件分析其图像。结果 Ｈ２Ｏ２的染毒浓度在２５００μｍｏｌ／Ｌ以下时，尾长、尾面积、尾矩和尾积分等指标均有剂量－效主尖关系（Ｔ＝３７℃时，ｒ分别为０．６８     

Comparison of low-temperature hydrogen peroxide gas plasma sterilization for endoscopes using various Sterrad models

This study compared the effectiveness of sterilizing four types of endoscope using different models of the Sterrad system (Sterrad 50, 100, 100S and 200). Sterilization levels meeting international requirements were attained in all cases with carriers inoculated with Geobacillus stearothermophilus spores. The endoscopes were tested in half cycles ('overkill'). This is the first study to compare the Sterrad models marketed to date in terms of effective sterilization of endoscopes with narrow lumens.     

Stimulation of hydrogen peroxide production by drinking water contaminants in HL-60 cells sensitized by retinoic acid

Chemical carcinogens, such as chloroform and trichloroethylene, are present in drinking water in Japan. As these contaminants are believed to have a role in carcinogenesis, we examined if chloroform and trichloroethylene, as well as methylene chloride, xylene, benzene, and ethanol, have the ability to generate hydrogen peroxide (H₂O₂) in human polymorphonuclear leukocytes (PMN) and human leukemia (HL-60) cells. Methylene chloride, benzene, xylene, trichloroethylene, and ethanol did not increase cellular H₂O₂: production as measured by flow cytometry nor as observed by confocal laser microscopy. In PMN and RAuntreated HL-60 cells chloroform did not significantly affect H₂O₂ levels. However, in HL-60 cells sensitized by pretreatment of 10 nM retinoic acid (RA) for 12 h, chloroform induced a significant increase in H₂O₂, but the increase induced by trichloroethylene was not significant. The observed increase in fluorescence was confirmed using a confocal laser microscope. These results indicate that chloroform and trichloroethylene may stimulate H₂O₂ production in HL60 cells sensitized by pretreatment of RA. Our method may be useful to test if weak stimulants can stimulate intracellular H₂O₂ production.     

Comparison between personal sampling methodologies for evaluating diesel particulate matter exposures in mines: submicron total carbon corrected for the adsorption of vapor-phase organic carbon vs. respirable total carbon

In the mining industry, personal measurements of elemental and total carbon are frequently used as surrogates of diesel particulate matter (DPM) exposure, and the respirable or submicron fractions are usually measured. However, vapor-phase organic carbon (OC) can be adsorbed in the filters, interfering with total carbon results. This study presents a comparative evaluation between the submicron fraction of DPM concentrations corrected for the adsorption of the vapor-phase OC (dynamic blank), and the respirable fraction of DPM corrected for a field blank. Respirable and submicron fractions of total carbon (TC_R and TC₁) and elemental carbon (EC_R and EC₁) concentrations were sampled in parallel, in the workers’ breathing zone, in an underground gold mine. A total of 20 full-shift personal samples were taken for each size fraction. Field blanks were collected each day for both the submicron and respirable fractions, while dynamic blank correction was also applied for the submicron fraction. TC_R presented a larger and statistically different geometric mean concentration compared to TC₁ (98 µg/m³ vs. 72 µg/m³; p = 0.01), while the concentrations of EC_R and EC₁ were not statistically different (58 µg/m³ vs. 54 µg/m³; p = 0.74). Average TC_R/EC_R ratio was 1.7, while the TC₁/EC₁ ratio was 1.3. In addition, 93% of EC had an aerodynamic size lower than 1 µm, while the proportion of TC particles in the submicron fraction was lower (73%). Finally, a similar quantity of OC was found when analyzing the dynamic and field blanks of the filters with the submicron fraction selective size (24 µg and 22 µg, respectively). In conclusion, the correction for the vapor phase OC by the dynamic blank was not a significant correction in our study design compared to the field blank samples. This study suggests that the differences in TC may be explained by the different aerodynamic fractions of DPM collected. In addition, elemental carbon measurements did not seem to be extensively affected by the aerodynamic size of the particles collected.     

北京市大气颗粒物中多环芳烃及碳元素分析

目的了解大气颗粒物PM_2.5与PM₁₀中多环芳烃及有机碳、元素碳的污染特征。方法2006年6月16～18日和6月20～22日于北京市城区设置采样点,采集大气颗粒物PM_2.5与PM₁₀,并对其中的17种多环芳烃及有机碳、元素碳进行了分析。结果PM_2.5与PM₁₀中多环芳烃的平均质量浓度分别为0.011～2.846和0.013～4.415ng/m³;PM_2.5与PM₁₀中有机碳和元素碳的平均质量浓度分别为28.56,8.75μg/m³和41.14,15.43μg/m³。结论采样时间内,4环和5环多环芳烃是PM_2.5与PM₁₀中17种多环芳烃的主要成分;含碳组分在PM_2.5与PM₁₀中所占比例相当,碳仍然是2种粒子中的主要成分之一。