分段流动分析法测定海水中挥发酚

研究了分段流动分析法测定海水中痕量挥发酚。在实验优化的最佳条件下测定海水中挥发酚,与国家标准方法有良好的相关性。方法的相对标准偏差(RSD)为1.9%,略优于国家标准方法,且操作简便。应用于海水中挥发酚的分析,取得结果满意。     

太阳能海水淡化系统经济性分析与研究

利用单因素分析方法,计算三效塔式太阳能海水淡化系统各个参数对太阳能海水淡化系统淡水生产成本的单因素影响值,分别给出太阳能集热系统成本、储热水箱成本、海水淡化装置成本、装置运行年消耗动力费用、设备使用年限和淡水年生产总量等参数对淡水生产成本影响的程度,明确降低淡水生产成本的方向,有助于太阳能海水淡化装置的深入研究。     

Flow injection flame atomic absorption determination of Cu, Mn and Zn partitioning in seawater by on-line room temperature sonolysis and minicolumn chelating resin methodology

A flow-injection system is developed for Cu, Mn and Zn partitioning in seawater by flame atomic absorption spectrometry. The first approach is where the trace metal species are fractionated in situ, but analysis is performed by using a flow injection manifold in the laboratory. This operational mode is used for the determination of the dissolved labile metallic fraction and is based on the elution of this fraction from a minicolumn packed with a chelating resin containing iminodiacetic acid groups (Serdolit Chelite Che) loaded in situ with the sample. The second is used for the determination of total dissolved concentrations of trace metals. This last mode is based on the retention/preconcentration of total dissolved metals on the chelating resin after on-line sonolysis of seawater samples acidified with diluted nitric acid to breakdown the metal-organic matter complexes. The figures of merit for Cu, Mn and Zn determinations in both fractions are given and the obtained values are discussed. The fractionation scheme is applied to the analysis of coastal seawater samples collected in Galicia (Northwest, Spain). The results of fractionation showed that Mn and Zn are mainly in the labile fraction, while Cu was mainly present in the organic fraction.     

The distribution of dissolved thallium in the different water masses of the western sector of the Ross Sea (Antarctica) during the austral summer

Vertical profiles for total dissolved thallium were obtained at five sites in the western sector of the Ross Sea (Southern Ocean), Antarctica. Thallium is estimated to have a natural mean seawater concentration between 50 and 65 pmol L^{− 1} with higher values in the North Pacific (65 ± 5 pmol L^{− 1}) and lower in the Bay of Biscay and Irish Sea (49 ± 3 pmol L^{− 1}). Our samples show a concentration varying from 22 to 55 pmol L^{− 1} with a mean value of 46 pmol L^{− 1}, depending on depth, dissolved oxygen, salinity and local topographic characteristics. The analyses were performed using an ICP-SFMS that has enabled us to obtain reliable Tl concentration measurements with a relative standard deviation of better than 2.5% and a detection limit, calculated as three times the standard deviation of the “blank signal” of 0.69 pmol L^{− 1} (1.60 pmol L^{− 1}, obtained analysing four blank solutions (n = 5) prepared with the same water and acid used for the dilution/acidification steps). Thallium appears to have a nearly conservative distribution in seawater as highlighted also from the comparison with the profiles of two seawater conservative elements: molybdenum and uranium; however it also highlights the presence of a reactive component of thallium, which is more influenced by the presence of particulate matter, oxygen content and fluorescence.     

Determination of Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb in seawater using high resolution magnetic sector inductively coupled mass spectrometry (HR-ICP-MS)

A novel method, combining isotope dilution with standard additions, was developed for the analysis of eight elements (Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb) in seawater. The method requires just 12 mL of sample and employs an off-line pre-concentration step using the commercially available chelating resin Toyopearl AF-Chelate-650M prior to determination by high resolution inductively coupled plasma magnetic sector mass spectrometry (ICP-MS). Acidified samples were spiked with a multi-element standard of six isotopes (⁵⁷Fe, ⁶²Ni, ⁶⁵Cu, ⁶⁸Zn, ¹¹¹Cd and ²⁰⁷Pb) enriched over natural abundance. In addition, standard additions of a mixed Co and Mn standard were performed on sub-sets of the same sample. All samples were irradiated using a low power (119 mW cm⁻²; 254 nm) UV system, to destroy organic ligands, before pre-concentration and extraction from the seawater matrix. Ammonium acetate was used to raise the pH of the 12 mL sub-samples (off-line) to pH 6.4 ± 0.2 prior to loading onto the chelating resin. The extracted metals were eluted using 1.0 M Q-HNO₃ and determined using ICP-MS. The method was verified through the analysis of certified reference material (NASS-5) and the SAFe inter-comparison samples (S1 and D2), the results of which are in good agreement with the certified and reported consensus values. We also present vertical profiles of the eight metals taken from the Bermuda Atlantic Time Series (BATS) station collected during the GEOTRACES inter-comparison cruise in June 2008.     

Sequential injection analysis for automation of the Winkler methodology, with real-time SIMPLEX optimization and shipboard application

A multipurpose analyzer system based on sequential injection analysis (SIA) for the determination of dissolved oxygen (DO) in seawater is presented. Three operation modes were established and successfully applied onboard during a research cruise in the Southern ocean: 1st, in-line execution of the entire Winkler method including precipitation of manganese (II) hydroxide, fixation of DO, precipitate dissolution by confluent acidification, and spectrophotometric quantification of the generated iodine/tri-iodide (I₂/I₃⁻), 2nd, spectrophotometric quantification of I₂/I₃⁻ in samples prepared according the classical Winkler protocol, and 3rd, accurate batch-wise titration of I₂/I₃⁻ with thiosulfate using one syringe pump of the analyzer as automatic burette.In the first mode, the zone stacking principle was applied to achieve high dispersion of the reagent solutions in the sample zone. Spectrophotometric detection was done at the isobestic wavelength 466 nm of I₂/I₃⁻. Highly reduced consumption of reagents and sample compared to the classical Winkler protocol, linear response up to 16 mg L⁻¹ DO, and an injection frequency of 30 per hour were achieved. It is noteworthy that for the offline protocol, sample metering and quantification with a potentiometric titrator lasts in general over 5 min without counting sample fixation, incubation, and glassware cleaning. The modified SIMPLEX methodology was used for the simultaneous optimization of four volumetric and two chemical variables. Vertex calculation and consequent application including in-line preparation of one reagent was carried out in real-time using the software AutoAnalysis. The analytical system featured high signal stability, robustness, and a repeatability of 3% RSD (1st mode) and 0.8% (2nd mode) during shipboard application.     

Assessment of Transition Metals Toxicity in Environmental Matrices Using Potentiometric Electrodes: Inorganic Mercury(II) in the Seawater as a Case Study

Chalcogenide glass electrode was applied to the detection of mercury(II) activity in the saline bromide buffers and artificial seawater at the activity levels corresponding to the acute toxicity. Mercury(II) toxicity in artificial seawater buffers and estuarine water was assessed using bioassay based on the luminescence of the marine bacterium A. fischeri. Electrode could detect mercury activity in the artificial seawater at the level of acute toxicity, which corresponded to pHg 23.2 (time of exposure 5 min.). Both electrode and bioassay indicated higher Hg²⁺ activity/toxicity in the estuarine water collected in the contaminated area. Quantification of Hg²⁺ activity in estuarine water using the mercury‐selective electrode requires calibration procedure to account for matrix effects.     

Scalable Antifouling Reverse Osmosis Membranes Utilizing Perfluorophenyl Azide Photochemistry

We present a method to produce anti‐fouling reverse osmosis (RO) membranes that maintains the process and scalability of current RO membrane manufacturing. Utilizing perfluorophenyl azide (PFPA) photochemistry, commercial reverse osmosis membranes were dipped into an aqueous solution containing PFPA‐terminated poly(ethyleneglycol) species and then exposed to ultraviolet light under ambient conditions, a process that can easily be adapted to a roll‐to‐roll process. Successful covalent modification of commercial reverse osmosis membranes was confirmed with attenuated total reflectance infrared spectroscopy and contact angle measurements. By employing X‐ray photoelectron spectroscopy, it was determined that PFPAs undergo UV‐generated nitrene addition and bind to the membrane through an aziridine linkage. After modification with the PFPA‐PEG derivatives, the reverse osmosis membranes exhibit high fouling‐resistance.

     

紫外光照还原-流动注射分光光度法测定海水中硝酸盐

在pH 8.2的二乙三胺五乙酸-三羟甲基氨基甲烷(DTPA-Tris)缓冲介质中,通过紫外光照射使NO3-还原为NO2-后,与显色剂反应生成吸收峰位于540 nm波长处的化合物,据此提出了在线紫外光照还原流动注射分光光度法测定海水中硝酸盐。经试验,选择30 g·L-1氯化钠溶液作为载流,所选定的反应圈及样品环的长度依次为180 mm和130 mm。硝酸盐的质量浓度在0.009~3.0 mg·L-1范围内与相应的吸光度呈线性关系,其检出限(3s/k)为4.63μg·L-1。对同一天然海水样品按此法测定其NO3-含量10次,测得其平均值为0.538 mg·L-1,相对标准偏差为0.34%,并求得NO3-的还原率为80%。另在6个海水样品中各加0.50 mg·L-1NO3-标准溶液,按方法做回收试验,测得其回收率在97%以上。     

火焰原子吸收光谱法测定人工海水中铁的不确定度评定

对火焰原子吸收光谱法测定人工海水中铁的测量不确定度来源进行了分析,并对各不确定度分量进行了量化,求得合成标准不确定度和扩展不确定度分别为0.027mg/L和0.053mg/L.