水体TOC与COD_(Cr)、BOD_5、COD_(Mn)相关性研究

通过对TOC、CODCr、BOD5及CODMn测定原理的研究,得出其理论相关性,并通过对国家标准样品、自配模拟样品及实际样品的测定,对TOC与CODCr、BOD5、CODMn的相关性进行了分析。结果表明,TOC与CODCr、BOD5、CODMn间具有明显的相关性,内插TOC系数法折算结果与标准法测定结果无显著性差异,该研究为以TOC值推算CODCr、BOD5、CODMn及TOC标准的制定提供了依据。     

Perkin-Elmer240C元素分析仪测定泉水中的有机碳

目前水中有机物污染程度的标志可分为四项:生物化学需氧量(BOD)、化学耗氧量(COD)、总有机碳(TOC)和总需氧量(TOD)。另外紫外线吸收法(UV法)也已引起人们的注意。利用Perkin-Elmer240C元素分析仪测定水中的有机碳已有报导,他们是通过     

自动TOC仪测定环境水中CODCr

化学需氧量CODCr反映了水中受还原性物质污染的程度,水中还原性物质包括有机物、亚硝酸盐、亚铁盐、硫化物等。水受有机物污染是很普遍的,因此化学需氧量也作为有机物相对含量之一,CODCr是我国实施排放总量控制的指标之一。总有机碳（TOC）,是以碳的含量表示水体中有机物质总量的综合指标,常被用来评价水体中有机物污染的程度。近年来,国内外已研制各种类型的TOC分析仪。     

岩溶地下水中溶解性有机碳测定方法的探讨

总有机碳(TOC)是以碳的含量来表示环境水体中有机物总量的综合指标,是反映水体受污染程度的重要指标。溶解性有机碳(DOC)是总有机碳的一种,通常定义为通过一定孔径(0.22～0.7μm)的滤膜后,水质中所含有机碳的含量[1]。水体中DOC的存在形式主要有溶解态、胶体态和少量较小     

测定饮用水中总有机碳新方法的研究

为了更准确地分析饮用水体中有机物的污染程度,采用燃烧氧化―非分散红外吸收法中直接法和差减法相结合的新方法测定饮用水中总有机碳(TOC),对单独使用直接法或差减法进行了优化。通过实验确定了该方法的检出限为0.12 mg/L,相对标准偏差为0.62%～1.97%,加标回收率为94%～102%,可用于测定饮用水中的总有机碳。     

电感耦合等离子体原子发射光谱法测定过氧化氢中总碳的含量

总碳(TC)的测定常采用TOC测定仪,TOC测定仪是将样品中的含碳化合物(有机和无机)通过催化氧化转化为二氧化碳,再以非分散红外气体检测器检测二氧化碳,国家标准GB 1616-2003《工业过氧化氢4.5总碳含量的测定》即是基于这一原理[1],但在分析高盐、强酸和强腐蚀性样品时,TOC测定仪具有一定的局限性,因样品易腐蚀仪器的转化炉,     

高温氧化红外分析法测定江水中总有机碳

本文介绍在文献基础上用高温氧化红外分析测定江水中总有机碳(TOC)。特点是①既具有分别测定水中总碳与无机碳,从二者差值求出总有机碳的高低温炉的流程;又具有提供“无碳”空气流,可先     

近红外光谱法快速测定水体有机污染物的方法研究

有机污染物是水体主要污染物之一,急需建立简单快速无污染的监测技术。本文将近红外光谱技术应用于水体有机污染物的测定,建立化学需氧量(COD)和生化需氧量(BOD5)的分析方法。结果表明,采用偏最小二乘算法、以近红外光谱的一阶导数谱建立的分析模型对水样COD和BOD5的测定均取得较好的效果。该分析模型对水样COD和BOD5的预测值和标准值之间的相关系数分别达到0.991和0.998,校正集的均方根偏差(RMSEC)相当于水样平均COD和BOD5值的4.3%和1.9%,满足日常监测的需要。分析模型对预测集样品的均方根偏差与RMSEC接近,表明该分析模型具有较好的适用性。采用近红外光谱法测定水体COD和BOD5等有机物指标结果可靠,为水体有机物污染的快速测定提供了一种可行的分析技术。     

催化裂化加氢色谱法测定水中总有机碳

前言水中有机物质的含量是评价水质的一个重要指标,常以总有机碳(TOC)表示之。其测定方法已有很多报导。本文介绍一种新的分析流程:先使水中有机物在镍催化剂上直接裂解加氢成甲烷,用氢火焰离子化检测器测定水样中总碳(有机碳与无机碳之和)。然后将水样通过150℃载有磷酸的石英毛层,使碳酸盐分解为二氧化碳,并在镍催化剂上还原为甲烷,按上法测定无机碳,由二者之差得出总有机碳。     

水环境中有机污染物生化需氧量的测定

本文从理论和实践上讨论了水质监测中有机污染物生化需氧量(BOD)测定中的有关问题。其中包括BOD测定中发生的生化反应过程，好氧生化反应速率及速率常数，影响BOD测定结果的各种因素，BOD测定技术，以及BOD与COD、TOC的相关性。     

ICP-AES测定铀污染土壤植物中铀的研究

采用电感耦合等离子体发射光谱(ICP-AES)对铀污染土壤植物中铀的测定方法进行了研究.在λU385.958 nm处,选择了仪器的最佳工作条件,考察了酸度和常见共存元素对测定的干扰情况,并且对比了干灰化消解和湿式消解对测定的影响.研究发现2%硝酸溶液为最佳介质,干扰离子对测定没有显著影响,干灰化消解比湿式消解得彻底.在选定条件下,方法检出限为0.18 mg·L-1,测定下限为0.61 mg·L-1,5.0000 mg·L-1的铀标准溶液的相对标准偏差RSD(n=10)为0.81%,方法回收率为96.2%～106.2%.该方法操作简单,快速.结果表明,用ICP-AES测定铀污染土壤植物样品中的铀是可行的.     

测定血清中Na 含量不确定度的评定

对血清中Na离子含量的测量不确定度进行评定。不确定度的来源主要包括Na离子标准工作液的配制过程、血清样品的定容消化制备、标准曲线拟合、钠离子各分量不确定度的合成等引入的不确定度计算出各分量的不确定度,通过合成得到测量结果的合成不确定度、扩展不确定度及测试结果的报告形式。     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Production of radicals in the ozonolysis of propene in air

Radical production in the ozonolysis of propene in air was monitored directly by a peroxy radical chemical amplification (PERCA) instrument at room temperature (298±2 K) and atmospheric pressure (1×105 Pa). The ozonolysis reactions were conducted in a flow tube under pseudo-first-order conditions for ozone. The decay in ozone was calculated based on reaction time tr and effective rate constant keff (keff = k1[C3H6]0)) for the ozone-propene reaction. The total radical yields relative to consumed ozone were d...     

Kinetics of dehydration in chelates of quinones involved in photosystem-II

The solid-state deaquation of thetrans- andcis-oximates of lawsone (I) and phthiocol (II) with cobalt(II) was investigated by means of non-isothermal thermogravimetry. The modes of deaquation during the thermolyses of hydrated oximates of (I) and (II) with compositions CoL₂·2H₂O were compared. The weight lossvs. temperature data were treated by using the Coats and Redfern relations. The kinetic data support a rearrangement-type mechanism for the deaquation of the oximate of phthiocol. TheE _a values for both the ligands and water molecules were found to be 23 kJ/mol.

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Zusammenfassung Mittels nichtisothermer Thermogravimetrie wurde die Dehydratation der trans- und cis-Kobalt(II)-oximate von Lawson (I) und Phthiokol (II) untersucht. Die Arten der Dehydratation während der Thermolyse der hydratierten Oximate von (I) und (II) mit der Zusammensetzung CoL₂·2H₂O wurden verglichen. Bei der Auswertung der Massenverlust-Temperatur-Daten wurden Coats-Redfern Beziehungen angewendet. Die kinetischen Daten bekräftigen einen Umlagerungsmechanismus für die Dehydratation des Oximates von Phthiokol. DieE _a Werte betragen sowohl für die Liganden als auch für Wasser etwa 23 kJ/mol.

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- - (I) (II) . I II CoL₂ · 2₂ . -. . _a , 23 · ^–1

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Use of matrix-modifiers in atomic-absorption determination of chromium in argillites

The direct atomic-absorption determination of chromium in argillites, without preliminary concentration and separation, has been studied. A map of selective flame zones for determining Cr in argillites has been designed. An express method for determining Cr in Estonian argillites has been suggested.     

Effect of vibration in processes of structure formation in polymers

It was shown that the strength characteristics of the samples produced from thermoplastics (low density polyethylene, polyamide 6, Armamid, and polyethylene terephthalate) increase as a result of short vibration treating with a frequency close to that of natural vibrations of the structural elements.