火焰原子吸收测定中的背景吸收和基体干扰

为了探讨火焰原子吸收法测定成分复杂样品时干扰的影响,采用扣除背景的方法来排除背景吸收,采用标准加入法来消除基体干扰的影响。通过对上述方法的对比实验,绘制相应的工作曲线图,能直观、准确地反映出背景吸收和基体干扰对样品测定的影响程度。扣背景和采用标准加入法两者结合使用能达到使样品测定结果准确可靠的目的。     

分子光谱技术在水体微塑料监测中的应用

水域、陆地和空气中的微塑料污染不仅对人们赖以生存的生态系统有潜在危害,而且对人类的身体健康存在持续性危害。针对这些污染问题开展研究的首要任务之一就是需要鉴定微塑料的成分,从而明确可能产生污染的源头以及引起污染的途径。分子光谱技术是鉴别微塑料最常用的分析方法之一,尤其是红外光谱法和拉曼光谱法。建立了基于分子光谱技术的水体微塑料检测方法,可实现对水体中1～5 000μm尺寸范围内的微塑料的自动化测试。其中,尺寸大于10μm的微塑料颗粒物可以通过显微红外光谱仪进行检测,尺寸大于1μm的微塑料颗粒物可以通过显微拉曼光谱仪进行检测。该方法操作简单、检测速度快、结果呈现直观,可作为微塑料检测的有力工具。     

南海区平台石油的特征荧光光谱分析

通过对南海区平台石油进行普通荧光光谱、同步扫描荧光光谱、导数荧光技术和三维荧光技术扫描,立体地了解各原 油样品荧光光谱特征,为科学鉴别濒发的海上溢油来源提供科学的依据。实验中综合分析了6个平台原油样品,并与标准原油 进行光谱对比,找出了这些样品的光谱数字化特征。     

区域土地利用类型对水源水中溶解性有机物丰度和荧光组分的影响

以潮白河密云段水体为研究对象,采用三维荧光光谱法及平行因子分析解析了潮白河饮用水源中溶解性有机物(DOM)来源和荧光特性,结合方差分析探讨了不同季节和区域土地利用类型对DOM浓度和荧光组分强度的影响.结果表明,潮白河密云段水体荧光溶解性有机物(FDOM)由5种荧光组分组成,包括微生物腐殖质2种,自生酪氨酸,还原醌类和陆...     

基于间隔偏最小二乘法短程硝化反硝化中无机盐氮的近红外光谱

采用序批式活性污泥反应器(SBR)研究短程硝化反硝化系统中稳定条件下无机盐氮的变化规律,利用小波去噪法对无机盐氮的近红外光谱进行预处理,并用间隔偏最小二乘法(iPLS)建立无机盐氮含量的校正模型(iPLS模型).结果表明:小波去噪法对原始光谱中的部分噪声进行滤除,从而提高了模型的精度.采用最小二乘法对预处理后的光谱进行建模,优选出最佳波长区间并将光谱划分为20个子区间,优选出的氨氮特征波数为8243~8663cm-1,亚硝酸盐氮特征波数为4000~4420cm-1.所建模型对氨氮、亚硝酸盐氮校正时的相关系数(rc)分别达到0.9582、0.9544,校正均方根误差(RMSECV)分别为0.0321、0.0406;预测时的相关系数(rp)分别为0.9184、0.8816,预测均方根误差(RMSEP)分别为0.0790、0.0451.采用实际污水为原水时校正模型对氨氮、亚硝酸盐氮预测的相关系数(rp￠)分别为0.9190、0.8739,预测均方根误差(RMSEP′)分别为0.0578、0.0229.模型对氨氮和亚硝酸盐氮的预测总体效果较好.用小波去噪和最小二乘法建立模型不仅能有效减少建模所需变量数、缩短运算时间,而且模型预测精度较高,为无机盐氮的快速测定提供了一种可行的分析技术.     

A simple and robust method for determination of neem (Azadirachta indica A. Juss) oil in neem oil coated urea

The production of neem oil coated urea (NOCU), a technology developed by the Indian Agricultural Research Institute, has been grown to over 2.0 million tons per year. The estimation of neem oil content in NOCU is important due to its significance in ensuring agronomic efficiency. Therefore, this study was taken up to develop a simple method for the determination of neem oil in NOCU. The procedure involves extraction of neem oil from NOCU; saponification of extracted oil; oxidation of released glycerol to formaldehyde, and subsequent conversion of formaldehyde to a dihydrolutidine derivative. Its concentration was determined spectrophotometrically. The recoveries of neem oil from NOCU with oil load of 500 and 1000?ppm were 87.6?±?3.0% and 90.0?±?4.8% respectively with direct method; and improved to 92.6?±?4.0% and 96.7?±?3.8% after including the in situ purification. A simple method based on the Hantzsch reaction was developed for the determination of neem oil in NOCU. This method is superior to earlier methods in terms of sensitivity, simplicity, and time required.     

Estimation of Similarity in the Qualitative Composition of Humic Substance in Marine Sediments By Means of an Uv-Spectroscopic Library

In this paper a method for the study of the qualitative similarity of extractable humic substance (EHS) in marine sediments based on the realisation of UV spectral library of EHS is described. the spectral library was built including the digitised spectra of humic substance extracted from several marine sediments (46 samples) and two samples of standard materials (lignin sulphonate and humic substance) in a Statistica data file. the data matrix was elaborated by means of different multivariate statistic techniques such as Cluster Analysis (CA), Principal Components Analysis (PCA) and the univariate technique Spectral Correlation Analysis (SCA). This approach allows us to show the contribution of different organic compounds (aromatic, lipid and acid) to the composition of EHS and moreover it evidences also the structural characteristics of EHS in terms of similarities in the qualitative composition of samples such as presence of terrestrial and/or vegetal contributions. the UV library is an objective tool to study the qualitative composition of EHS and it represents a complementary approach to the most common methods based on the application of spectroscopic (IR, ¹³CNMR), potentiometric and chromatographic techniques.     

Characterization of fulvic acids during olive mill waste composting (Elemental,Thermal and fluorescence analyses)

Elemental analysis, fluorescence spectroscopy and differential scanning calorimetry (DSC) were applied to the study of fulvic acids isolated from different stages during olive mill waste composting. The fulvic extracted acids are characterized by a high nitrogen content and O/C ratio values that may result from the high degree of humification and the synthesis of more condensed humic complexes. This was confirmed by fluorescence spectroscopy in the synchronous-scan mode by the decrease of shoulder intensities at intermediate wavelengths indicating the increase of polycondensation and conjugation of unsaturated structures and the greater uniformity of fluorophores. Fluorescence spectra in the emission, excitation and synchronous modes became simpler with compost maturation. This was confirmed by DSC results which proved the high degree of polycondensation of aromatic nuclei of fulvic acid molecules during olive mill waste composting.     

Application and mechanism of polysaccharide extracted from Enteromorpha to remove nano-ZnO and humic acid in coagulation process

Green source Ep was extracted from marine alga waste. The molecule model structure of Ep was studied and constructed. PAC-Ep coagulation system improves the efficiency of removal efficiency. Synergistic effects between NPs and HA make a big difference to enhance efficiency. Mechanism is charge neutralization, hydrogen bonding and adsorbing-complexing Enteromorpha polysaccharide (Ep) extracted from alga a novel green coagulant aid for nanoparticles (NPs) and heavy metal ions removal and the structure of EP was intensively studied in this study. The integration of Ep with polyaluminum chloride (PAC-Ep) coagulants exhibited higher coagulation performance than that of the polyaluminum chloride (PAC) because of the negatively charged NPs suspension and humic aid (HA) solution. Significant high removal efficiencies of dissolved organic matter (94.1%), turbidity (99.3%) and Zn ions (69.3%) were achieved by the PAC-Ep coagulants. The dual-coagulation properties of PAC-Ep for different pollutants was based on multiple mechanisms, including (i) Al³⁺ charge neutralization; (ii) hydroxy aluminum hydroxyl bridging formed polynuclearhydroxy complexes bridge and sweep colloidal particles; (iii) adsorption and bridging of Ep chain for the NPs and heavy metal ions. Results indicated that the destabilization of colloid was induced by the coexisting HA and higher removal was achieved as ions adsorption was enhance in the presence of HA complexation. On the basis of that, the extraction of polysaccharide is a promising candidate for its high coagulation performance in water treatment.