神经网络—紫外光度法同时测定水中硝酸盐氮和亚硝酸盐氮

研究了硝酸盐和亚硝酸盐的紫外吸收光谱。利用基于ＢＰ算法的人工神经网络对光谱数据处理,提出同时测定水样中硝酸盐氮和亚硝酸盐氮的新方法。对人工合成试样和实际水样进行了测定。结果满意。采用均匀设计法构建试验系统及网络运行参数的选择。效果良好。     

水中硝酸盐氮两种蒸干方法测定结果比较

GB/T 5 75 0 - 1985《生活饮用水标准检验方法》中硝酸盐氮测定 ,待测水样是在水浴上蒸干后进行测定的 ,5 0 .0ml水样在水浴上蒸干大约需要 2 .5h ,而隔着石棉网在电炉上加热蒸干则只需约 30min ,本法将两种方法作出对比试验。1　主要仪器与试剂电炉 (12 0 0W ) ,恒温水浴锅 (37～ 10 0℃ ,2 5 0 0W ) ,试剂和标准溶液均参照GB/T 5 75 0 - 1985中 2 9.1.4进行配制。2　测定方法(1)样品蒸干处理 :吸取水样 5 0 .0ml于 10 0ml蒸发皿中 ,垫上石棉网 ,放在电炉上加热至近干 ,去掉电源 ,让余温使蒸发皿中的水分蒸干。另取同一水样5 0 .0ml在…     

智能红外测油仪应用于水质矿物油的测定

将智能红外测油仪应用于水质测试中水样中矿物油的测定,对测定中各影响因素,包括零点的设置,石英吸收皿的选择,四氯化碳质量的挑选以及脱水效率等进行了试验并优化.在所选的条件下对水样中矿物油作了测定,回收率在 99.2%～100.2%之间.     

电导法测定地表水中全盐量的探讨

根据模拟水样与实际水样在电导率与全盐量的关系上有较好的吻合性，介绍了电导率法测定地表水中全盐量的方法。与传统重量法相比，具有快速、简便、准确度高的特点。     

一堂环保活动课

介绍了一堂环保活动课,教师组织学生,在专家的指导下,对衡水湖水质监测,学生亲身体验取水样、进行pH、透明度及化学需氧量等的测定的全过程。充分发挥了学生自主学习的积极性和创造性。在社会实践中提高学生发现问题、分析问题和解决问题的能力,训练设计实验与动手操作技能,增强环保意识,培养团结协作和创新精神。把当代高职生培育成为高素质创新型实用人才。     

简便快速的硫化氢测定法

本文提出了有一种简易快速测定剂来测定水样中的硫化氢的方法。该法的检出限为０．１ｍｇ／Ｌ，对１．０１ｍｇ／Ｌ的Ｈ２Ｓ样品７次测定的相对标准偏差＜４．１％，１ｈ能测定１２个样品。用本测定了几种水样中的Ｈ２Ｓ含量，回收率为８４％－１０５％。应用它可上标准法的４ｈ左右缩短到５ｍｉｎ；使分析成本降低９／１０；不需配制一系列分析试剂和仪器，只需一支小型塑料管和几片药片，便于渔业水质和环境水质的野外现场监测。     

非过滤法共沉淀富集—火焰原子吸收测定饮水中镉铜铅

在中性或弱碱性条件下，向被没水样中加入适量Ｂｉ＾３＋和硫化钠，使水样中Ｃｄ＾２＋，Ｃｕ＾２＋，Ｐｂ＾２＋与Ｂｉ＾３＋一起硫化物（ＣｄＳ，ＣｕＳ，ＰｂＳ）和Ｂｉ２Ｓ３的共沉淀，加入明矾加速硫化物的沉淀，凝结，然后用虹吸法吸去上层清液（无须过滤），将沉淀物用热稀硝酸溶液，以火焰原子吸收法测定这三个元素的含量。方法简便，实用，且具有较高的准确率和精密度，尤其适于对大体积水样的沉淀富集。     

SPME-GC联用测定环境水样中的酚类化合物

建立了固相微萃取与气相色谱联用技术测定环境水样中酚类化合物的方法. 探讨了pH、离子强度、萃取头类型、萃取时间以及解析时间等条件对酚类化合物萃取量的影响, 优化了GC仪器条件. 在优化的条件下, 酚类化合物的响应值与浓度有良好的线性关系, 线性范围为0.20～200 μg/L, 检出限在0.019～0.10 μg/L之间, 相对标准偏差(RSD, n=5)为4.4%～11%, 水样平均加标回收率为92.2%～101.9%, 所建立的方法可测定环境水样中的酚类化合物.     

酶法测定水中的尿素含量

利用脲酶、谷氨酸脱氢酶偶联催化尿素水解的原理,通过测定还原型烟酰胺腺嘌呤二核苷酸吸光度变化率得出其酶促反应速度,对应不同的尿素浓度制得标准曲线,讨论了ｐＨ值和抑制剂对测定的影响,实测了水样中尿素的含量。     

环境水中化学需氧量的FI分光光度法自动在线检测

本文将流动注射分光光度法用于环境废水中化学需氧量（ＣＯＤ）的自动在线检测，方法线性范围在０－１００ｍｇ／Ｌ之间，相对标准偏差＜２％以葡萄糖和苯二甲酸氢钾混合液制备标准溶液，对标准参考水样ＣＯＤ含量（Ｃｒ值）的测定结果表明两者有良好的相关性（Ｒ＝０．９８８０）对环境水样中ＣＯＤ含量的动态变化连续１０ｈ模拟试验，自制的在线过滤装置稳定，未发生堵塞现象；该系统可以较好地跟踪水样中ＣＯＤ浓度的实际变化     

Chemometrics characterisation of the quality of river water

Within the period from autumn 1990 to spring 1999 (from October to April in each period) 207 samples were collected and the measurement of 19 physical and chemical variables of the Mura river, Slovenia, were carried out. These variables are: river flow, water temperature, air temperature, dissolved oxygen, deficit of oxygen, oxygen saturation index, chemical oxygen demand (COD) in unfiltered and filtered samples, and biochemical oxygen demand after 5 days (BOD5) in unfiltered and filtered samples, pH, conductivity, ammonium, nitrite, nitrate, and phosphate concentrations, adsorbable organic halogens (AOX), dissolved organic carbon (DOC), and suspended solids. For handling the results of all measurements different chemometrics methods were employed: (i) the basic statistical methods for the determination of mean and median values, standard deviations, minimal and maximal values of measured variables, and their mutual correlation coefficients, (ii) the principal component analysis (PCA), and (iii) the clustering method based on Kohonen neural network. The influences of season, month, sampling site, and sampling time on the pollutant levels were examined. Before 1993, the pulp and paper industry was the main source of pollutants because of large amounts of chlorine emission as a consequence of industrial treatment, the leaching of cellulose. After the year 1993, the technology was changed and the quality of the river water has improved. The improvement could be detected 1 year after the change of technology. For one part of water samples the river quality classes based on biological parameters were also determined. The correlation between the biologically determined quality classes and chemical measurements was sought. Consequently, the biological classification for the water samples based on the chemical analyses was studied.     

Validation of an environmental friendly segmented flow method for the determination of phenol index in waters as alternative to the conventional one

Phenolic compounds are a sort of common pollutants in water. Phenol index becomes an expedite indicator for the evaluation of the contamination level of water samples, in spite of the knowledge of the individual phenol and its derivatives are also important.In this work, an environmental friendly method for the determination of phenols, using a segmented flow system based on the conventional method's reactions without the liquid-liquid extraction step, was validated.Three linear dynamic ranges using C₆H₅OH: 1-10 μg l⁻¹, 10-200 μg l⁻¹ and 0.2-2.5 mg l⁻¹, with a coefficient of variation lower than 2%, were obtained. Several method's performance parameters were determined: limits of detection, limits of quantification, precision through duplicate analysis and trueness using the reference materials purchased from LGC Promochem, RTC no. QCI-043-2 Lot:P1. Measurement uncertainty was evaluated using an interlaboratory approach based on proficiency testing data. Relative combined uncertainty for phenols in water samples, , of 0.054 were obtained, in according to those imposed by the Portuguese Legislation: target for 1 μg l⁻¹ of phenol (surface waters) and target for 500 μg l⁻¹ of phenol (wastewaters).A high efficiency reduction and elimination of reagents and wastes, reduction of analysis time and exposition of the analyst were also obtained.     

化学教育，情暖隆德——厦门大学“化在宁夏”暑期社会实践

2019年7月20日至7月28日,厦门大学"化在宁夏"实践队前往宁夏隆德县进行以教育为主旨的暑期社会实践,其中包含三个具体的实践方向:科普化学知识、帮扶学生学业、增长爱国情怀。     

Modelling and prediction of retention in high-performance liquid chromatography by using neural networks

Summary Two analytical methods have been developed for the determination in water of 18 priority phenolics listed in US EPA method 604 and on EEC list 76/464. A solidphase extraction system using eight different sorbents packed in a precolumn was coupled on-line with a liquid chromatograph with UV detection. The ensuing method uses 50–100 mL of ground water; its performance was compared with that of an off-line method using Empore extraction disks and 1 L water samples. Phenol recoveries varied from <20 to 100% for concentrations in the range 0.1–10 g/L at an acid pH. The presence of the phenols in water was confirmed by using thermospray LC-mass spectrometry in the negative ion mode. The stability of the phenols in water was studied at a 10 g/l level in ground and estuarine water at acid pH (2.5–3) and at 4°C for 1 month. The system was validated by various interlaboratory exercises with samples containing 2,4,6-trichlorophenol and pentachlorophenol at concentrations from 0.1 to 0.5 g/L.     

Interpolation and approximation of water quality time series and process identification

Data records with equidistant time intervals are fundamental prerequisites for the development of water quality simulation models. Usually long-term water quality data time series contain missing data or data with different sampling intervals. In such cases artificial data have to be added to obtain records based on a regular time grid. Generally, this can be done by interpolation, approximation or filtering of data sets. In contrast to approximation by an analytical function, interpolation methods estimate missing data by means of measured concentration values. In this paper, methods of interpolation and approximation are applied to long-term water quality data sets with daily sampling intervals. Using such data for the water temperature and phosphate phosphorus in some shallow lakes, it was possible to identify the process of phosphate remobilisation from sediment.     

"新工科"视角下以学生为中心"一纵三横"创新人才培养模式

Under the new economic background, social development needs more high-quality innovative talents with strong engineering practice ability, strong innovation ability and international competitiveness. Based on "emerging engineering education" perspective, the student-centered and "Yi-Zong and San-Heng" education mode has been proposed by analyzing the traditional talent training mode, which will better improve the "new system" of military engineering education.     

毛细滴管数滴微型滴定法野外快速测定水中溶解氧

用毛细滴管数滴微型滴定法对水中溶解氧进行了现场快速测定。实验结果表明,该法的不确定度Urel(C)约为1.6%,与常量滴定法相当,符合国家标准。该法以自制的液滴体积为0.01~0.02 mL的聚乙烯毛细滴管就地进行滴定,避免了水样长期保存和运输中产生的误差。其主要仪器外形小巧、便于携带,滴定快速、准确,滴定剂用量仅为65~100滴,完全能够满足现场快速水质测定和野外水环境监测的需要。     

Accurate quantification of PAHs in water in the presence of dissolved humic acids using isotope dilution mass spectrometry

The effect of dissolved humic acids on the recovery of PAHs from water samples has been investigated using a commercially available humic acid preparation as colloid model and a mixture containing the 16 EPA PAHs. The presence of humic acid reduced the extraction efficiency down to between 10 and 75%. An analytical protocol was therefore developed for the accurate determination of PAHs in the presence of humic acids based on isotope dilution mass spectrometry. The procedure compensates for losses due to sorption of PAHs and can be used for the determination of the total PAH concentration in water, i.e. dissolved PAHs plus PAHs adsorbed on colloids. To obtain reliable estimates it is essential to allow a certain time for equilibration between the isotope spike and the aqueous matrix which may vary between 5 and 24 h, in correlation with the water solubility of PAHs. The protocol allows one to recover the 16 PAHs studied at 94 to 105%. The expanded uncertainty of the measurements was 5–7% for all PAHs. Liquid–liquid extraction and solid-phase extraction in combination with the developed isotope dilution protocol performed equally well for the quantification of PAHs from water samples rich in colloidal material.      

热处理对憎水硅胶吸附水蒸气的影响

用甲基氯硅烷蒸气或溶液处理硅胶,均可制成憎水硅胶。关于憎水硅胶的吸附性能和热稳定性的研究,文献中时有报道。本文主要探讨以下3个问题:(1)在水蒸气吸附中,硅胶表面自由羟基和缔合羟基究竟哪种起主要作用;(2)从吸附水蒸气等数据讨论硅胶表面有机基团—OSi(CH_3)_3的热稳定性;(3)用二甲基二氯硅烷(DMCS)和三甲基氯硅烷(TMCS)处理的憎水硅胶,哪种硅胶的热稳定性较高。这些基本问题,不仅具有学术意义,对研究氧化物表面改性也有参考价值。