镧涂层塞曼效应石墨炉原子吸收法测定铜基合金中微量锡

本文采用塞曼石墨炉原子吸收法结合石墨管涂镧技术测定了铜基合金中微量锡。文章对比了涂镧管与非涂镧管测定锡时的原子化曲线对于镧涂层对实验结果的影响及酒石酸的作用进行了讨论，提出了镧化合物可能在管内起到催化作用的观点。实际样品测定相对标准偏差为４．４％，加标回收率１０１％。     

钯—硝酸镁基体改进剂石墨炉原子吸收光谱法测定六味地黄丸中锡

本实验建立了钯－硝酸镁基体改进剂石墨炉原子光谱法测定六味地黄丸中锡的方法，研究了基体改进剂的加入方式对测定的影响，方法的相对标准偏差为２．５％，回收率在９０％～１１０％之间，检出限为０．３ｎｇ／ｍＬ。本方法用于中成药中锡的测定。     

X荧光光谱法测定锡酸铅TDI还原型催化剂中锡和铅含量

报道了一种准确度高、分析步骤简单的锡酸铅TDI还原型催化剂中锡和铅含量的X射线荧光光谱方法（XRF）．设计制备了标准样品,研究了仪器测试条件下元素峰位的选择和背景扣除方法．结果表明：X荧光光谱法在不破坏样品的前提下完成对二氧化锡和铅含量的同时测定,重复实验10次,Pb实验相对标准偏差为0．37％;SnO2实验相对标准偏差0．61％。     

ICP-AES法测定锡精矿中锡、铜、铅、铁的含量

建立了过氧化钠熔融分解样品、电感耦合等离子发射光谱法（ICP-AES）测定锡精矿中锡、铜、铅、铁的新方法。对试样分解方法、过氧化钠用量、元素分析谱线等进行了讨论。选择过氧化钠用量为2．0g,样品熔融温度为850~C,锡、铜、铅、铁分析谱线分别为189．991,324．754,220．353,259．940nm。将该方法应用于标准样品（BY0107—1）中Sn,Cu,Pb,Fe的测定,待测元素的回收率在92．0％-101．6％之间,检出限为分别为0．006,0．002,0．005,0．001μg／mL,测定结果的相对标准偏差为0．16％～2．11％（n=5）。     

钯－硝酸镁基体改进剂石墨炉原子吸收光谱法测定六味地黄丸中锡

本实验建立了钯－硝酸镁基体改进剂石墨炉原子吸收光谱法测定六味地黄丸中锡的方法。研究了基体改进剂的加入方式对测定的影响。方法的相对标准偏差为２．５％，回收率在９０％～１１０％之间，检出限为０．３ｎｇ／ｍＬ。本方法可用于中成药中锡的测定。     

ICP-AES法测定锡青铜中锡和磷

锡青铜可作轴套材料,通常ω_(Sn)<10％,ω_p<0.5％。按国家标准分析方法,用GB 8002.2—87中次磷酸盐还原法测定锡,用GB 8002.3—87中钒钼酸吸光光度法测定磷。采用普通化学方法测定,分析过程长,应用试剂多。测定锡还要应用氯化高汞造成环境污染,测定磷要在标准系列中加入优级纯金属铜,消耗较多标准物质。本文用ICP-AES法测定锡和磷,具有准确、快速、消耗试剂少等优点。 1 仪器与工作条件 应用JY70PⅡ电感耦合等离子体发射光谱仪JY38扫描部分测定,该仪器所配全息光栅的刻线为3600条·mm~(-1),焦距1m,扫描步距0.002nm。 高压4.0kV,阳流410mA,栅流175mA。     

碱性氢化物发生—火焰原子吸收光谱法测定锡

对Ｓｎ－ＮａＯＨ－ＫＢＨ４体系进行了系统研究，采用三乙醇胺－ＥＤＴＡ联合干扰抑制剂，可消除一定量铁及合金元素的干扰，对于锡含量小于０．０１％的试样，用苯萃取锡后所有元素不干扰测定。测定液中锡量为０－４μｇ／１０ｍｌ，呈线性关系，灵敏度为０．００４ｍｇ／Ｌ／１％，检出限为０．００８ｍｇ／Ｌ，测定钢中大于０．００１％锡，结果满意。     

锡及锡铅合金分析方法的研究

锡及锡铅合金的测定方法文献多采用返滴定法及置换滴定法。按文献方法,对高纯锡及锡铅合金进行多次测定,测得结果偏低,误差较大。从实验中观察到:当加入(CH_2)_6N_4调pH=5—6时,便产生浑浊或沉淀。这一现象与锡易水解的性质是一致的。即无论是Sn~(2+)     

顺序注射氢化物发生-原子荧光光谱法同时测定中草药中的铅和锡

建立了一种顺序注射氢化物发生一原子荧光光谱法同时测定中草药中的铅和锡含量的方法,同时讨论了共存离子的干扰情况。结果表明,在最佳实验条件下,铅和锡的检出限分别为0．0253μg／L和0．0425μg／L,加标回收率为95．5％～103．1％,相对标准偏差小于5．2％,被测试样中共存的离子对铅和锡的测定没有干扰。该法操作方便、快速,用于中草药试样中铅和锡的同时测定,具有很好的可行性和实用性。     

电位滴定法测定锡基合金中的铅

研究用305型铅离子选择性电极为指示电极,电位滴定法测定锡基合金中铅的新方法。在测定体系中加过量的EDTA标准溶液络合铅,再用硝酸铅标准溶液滴定过量的EDTA,电位突跃明显,用二级微商法确定滴定终点和计算终点时耗用滴定剂的体积,方法准确度高,结果稳定,操作简便。并对测定条件和干扰离子的掩蔽作了试验,对样品中加标回收率达99.95％～100.02％。     

Differential impacts of solar UV radiation on photosynthetic carbon fixation from the coastal to offshore surface waters in the South China Sea

We carried out experiments during an expedition (14 August to 14 September, 2007) that covered up to 250,000 km(2) to investigate the effects of solar UV radiation (UVR, 280-400 nm) on the photosynthetic carbon fixation of tropical phytoplankton assemblages in surface seawater of the South China Sea. From coastal to pelagic surface seawaters, UV-B (280-315 nm) caused similar inhibition, while UV-A (315-400 nm) induced photosynthetic inhibition increased from coastal to offshore waters. UV-B resulted in an inhibition by up to 27% and UV-A by up to 29%. Under reduced levels of solar radiation with heavy overcast, UV-A resulted in enhanced photosynthetic carbon fixation by up to 25% in coastal waters where microplankton was abundant. However, such a positive impact was not observed in the offshore waters where piconanoplankton was more abundant. The daily integrated inhibition of UV-A reached 4.3% and 13.2%, and that of UV-B reached 16.5% and 13.5%, in the coastal and offshore waters, respectively.     

超声萃取-气相色谱-质谱联用测定海洋沉积物中39种多溴联苯醚残留

建立了超声萃取-气相色谱-质谱法测定海洋沉积物中39种多溴联苯醚残留的分析方法.样品用V(正己烷):V(二氯甲烷) =1:1混合溶液提取,超声(控制水浴温度为25 ℃)提取60 min,采用硅胶和氧化铝净化,负化学离子源-气相色谱-质谱法进行检测,39种组分图谱在49 min 内能得到很好的分离. 39种混合样品的检出限为0.003～0.10 μg/kg; 加标回收率为66.2%～118.6%;相对标准偏差为0.8%～18.2%.用于实际样品分析,结果令人满意.     

Triclosan determination in water related to wastewater treatment

Triclosan in the waste, river and sea water samples collected in Hong Kong was analyzed by using gas chromatography–ion trap mass spectrometry method. ¹³C₁₂-triclosan was used as internal standard for the quantitative analysis. Water samples were prepared and cleaned-up by using a C₁₈ solid-phase extraction cartridge. The recoveries of triclosan in spiked coastal water at three different concentrations ranged from 83 to 110%. The method detection limit was 0.25 ng/L for triclosan in 1-L water and the relative standard deviations and relative error were less than 11.0 and 12.3%, respectively (n = 3). The method was successfully applied to analyze water samples collected from rivers, coastal water bodies and wastewater treatment plants at ng/L levels.     

Tritium content as indicator of environmental character on Taiwan Island

Environmental characters have been established by tritium contents in well water, coastal seawater and reservoir water collected from various places around Taiwan island. Tritium concentrations of samples were detected by a liquid scintillation analyzer TRI-CARB-LSC 2550 TR mode, with a low level standard quench curve. After samples were concentrated by electrolysis, tritium concentration was detected in optimum conditions of LLLSA. An electrolytic enrichment technique was also developed with a eurrent density of 100 mA/cm² and 0.4–0.6% (Na₂O₂) electrolyte in concentrated samples. Data observed show a lower tritium concentration for coastal seawater than for wells in the same area. The tritium concentration ratio of well and coastal seawater on the western side of Taiwan is 4.000 and on the eastern side 5.801. Tritium content of reservoir water is related to the logarithm of effective volume capacity.     

Chemical composition variations,allelopathic, and antioxidant activities of Symphyotrichum squamatum (Spreng.) Nesom essential oils growing in heterogeneous habitats

The present study aimed to analyze the chemical composition of Symphyotrichum squamatum EOs growing in two different habitats to explore the ecological implication on the EOs production and evaluate their antioxidant and allelopathic potentialities. The EOs from the aerial parts collected from coastal Mediterranean belt and inland abandoned habitats in the Nile Delta of Egypt, were extracted and analyzed using gas chromatography-mass spectrometry. Sixty compounds were characterized as overall constituents of EOs from both samples. Sesquiterpenes were the main component and represented by 69.77% and 88.68% from coastal and inland sample, respectively. The coastal sample attained a relatively high content of monoterpenes compared to the inland sample. Major compounds from the EOs of the coastal habitat sample, were humulene epoxide, (-)-spathulenol, (-)-caryophyllene oxide, germacrene D, and α-humulene representing 59.72%. However, β-pinene, germacrene D, α-humulene, α-muurolene, humulene epoxide, (-)-caryophyllene oxide, and β-cadinene were the major compounds of EOs of the inland habitat sample, representing 63.70%. The correlation analysis revealed more correlation between the Egyptian inland S. squamatum and the Japanese ecospecies. However, the Egyptian coastal S. squamatum and Turkish ecospecies were more correlated to each other. The present data suggested that chemotypes of S. squamatum maintain their typical pattern despite ecological or climatic differences. The EOs of S. squamatum showed moderate antioxidant activity, wherein coastal and inland EOs have an IC₅₀ value of 382.53 and 559.63 μL L⁻¹, respectively. Also, the EOs from both habitats showed moderate allelopathic activity against the noxious weed Bidens pilosa. However, the activity of the coastal sample was more than inland one and could be attributed to the content of the major compounds, especially the oxygenated terpenes.     

Sulphur speciation of PM10 samples by XANES spectroscopy

Sulphur K-edge X-ray absorption near edge structure (XANES) spectroscopy was used to identify sulphur compounds in PM10 samples collected simultaneously at two sites with different environmental situations in the province of Trieste (NE of Italy), during summer and winter seasons respectively. The first site is an industrial site located near a steel mill plant and the second is a coastal site. The sulphur speciation at the industrial site has shown the presence of the following sulphur compounds in both seasons: organic compounds (thiophenes or Polycyclic Aromatic Sulphur Heterocycles — PAHs) and sulphates while in the winter season sulphites were also present. In the coastal site organic compounds (thiophenes or PASHs) and sulphate were found during winter season, moreover bisulphates were found during summer season. Relative percentages of the different sulphur compounds have shown that sulphate is the most abundant form of sulphur in the industrial site samples during both seasons and in the coastal site sample collected during the winter season (> 98%); in the coastal site sample collected during the summer season the relative percentages of bisulphate and sulphate were around 40% and 60% respectively.      

A multi-detector continuous monitor for assessment of <Superscript>222</Superscript>Rn in the coastal ocean

Summary Radon-222 is a good natural tracer of groundwater discharge and other physical processes in the coastal ocean. Unfortunately, its usefulness is limited by the time consuming nature of collecting individual samples and traditional analysis schemes. We demonstrate here an automated multi-detector system that can be used in a continuous survey basis to assess radon activities in coastal ocean waters. The system analyses ²²²Rn from a constant stream of water delivered by a submersible pump to an air-water exchanger where radon in the water phase equilibrates with radon in a closed air loop. The air stream is fed to 3 commercial radon-in-air monitors connected in parallel to determine the activity of ²²²Rn. By running the detectors out of phase, we are able to obtain as many as 6 readings per hour with a precision of approximately ±5-15% for typical coastal seawater concentrations.     

沉淀/共沉淀-膜富集-X射线荧光法快速分析近岸海水中的重金属

建立了近岸海水中多种重金属(铁、镍、锰、铜、锌及铅)的氢氧化物和硫化物的沉淀/共沉淀-膜富集-X射线荧光测定法.在海水样品中加入沉淀剂,使重金属离子生成氢氧化物或硫化物沉淀.沉淀经过滤截留,富集在膜上,直接以手持式X射线荧光仪检测.富集100 mL水样时,两种沉淀法的测定线性范围均为12.5～400 μg/L,即测定限均为12.5 μg/L.对各重金属浓度为100μg/L的试样连续测定7次,相对标准偏差(RSD)为3.7％～6.4％;氢氧化物沉淀法的检出限在1.32～7.84 μ g/L之间;硫化物沉淀法为1.94～11.0 μg/L.用本方法成功测定了厦门近岸海域及九龙江河口海水中的重金属浓度.基于样品酸化与否及过滤先后顺序的不同,本方法可用于海水和河口水样中可溶态、溶解态及游离态重金属的现场快速分析.     

Geochemical association of plutonium in sediments of the Trombay coastal environment

Geochemical association of plutonium in the coastal environment of Trombay has been studied. A sequential leaching method was employed for chemical partitioning of plutonium in sediments. The results show that 95±15% of plutonium was extracted by different leaching reagents out of which 85±14% was associated with organic matter and hydrous oxide and 9±4% with residual fraction.The presence of significant fraction of Pu bound with organic matter of the sediment is an important factor in determining the extent to which an element becomes available to bottom feeding biota and so enters the aquatic food chain.     

Application of pressurized fluid extraction technique in the gas chromatography-mass spectrometry determination of sterols from marine sediment samples

In order to determine steroid compounds in GC/MS an analytical method using pressurized fluid extraction (PFE) was developed. While extracting in-house reference material (coastal sediment) typical recovery in PFE ranged from 80 to 120% (+/-2.5-14.5) and the average extraction yield in PFE in comparison to conventional soxhlet extraction was 115%. In particular, the PFE showed higher extraction efficiency for C29 and dien sterols. Optimizing parameters such as temperature and pressure is critical in achieving this efficiency. Sterols in the sediment were derivatized with silyl reagent BSTFA in acetone for the final determination. A short column florisil cleanup offered the best separation of the GC/MS sensitive derivatives from co-contaminants. Thirty-three coastal sediment samples were analyzed using PFE and Soxhlet extraction methods. The results on extraction efficiency, silyl derivatization kinetics and purification efficiency demonstrated that PFE is far superior in extracting sterols from sediment samples. It is simple, fast, efficient and amenable for automation.