The determination of selenium in sea water,silicates and marine organisms

Spectrophotometric procedures are described for the determination of selenium in sea water, silicates (especially marine sediments) and marine organisms. Coprecipitation with iron(III) hydroxide at pH 4–6 is used to concentrate selenium and to separate it from many of the commoner elements. Separation from iron and other cations is achieved by ion exchange. Selenium is determined photometrically with diaminobenzidine. Isotope dilution with selenium-75 is used to correct results for the small losses occurring during the analysis. Silicates can be decomposed without loss of selenium by means of a mixture of hydrofluoric and nitric acids. The method of Cummins et al., with sulphuric and perchloric acids in presence of molybdate ion, is highly satisfactory for the decomposition of bio-materials. For sea water, which contains ca. 0.4–0.5 <mg Se/l, a standard deviation of 0.03 μg/l was obtained. A silicate sediment and a sea weed containing ca. 1.5 μg Se/g and 0.8 μg Se/g respectively gave coefficients of variation of 8.0% and 4.7%. The U.S. Geological Survey standard granite G1 was found to contain 2.5 ± 0.1 μg Se/g.     

Determination of arsenic in sea water,marine plants and silicate and carbonate sediments

Cocrystallization with thionalide in a 0.05 N sulphuric acid medium is proposed for the recovery of microgram amounts of arsenic from sea water and from solutions prepared by the decomposition of silicates and marino plants. After destruction of the organic precipitant, arsenic is determined photomotrically by means of a single-solution molybdenum blue method. The overall recovery for the whole process is 97-98%. Arsenic was determined in sea water with a coefficient of variation of 1.3% at a level of 2 μg As/l. Coefficients of variation of 2.6% and 1.7% were found, for the determination of the element in marine sediments and plants at levels of 6.6 μg/g and 1.7 μg/g respectively. The U. S. Geological survey standard granite G 1 was found to contain 1.2 μg As/g     

The spectrophotometric determination of chromium in sea water

The coprecipitation of chromium from sea water by several precipitates was examined. With hydrous iron(III) oxide a recovery of chromium of >99% was obtained within the pH range 7.0–9.0 at a chromium level of ca. 0.4 μg/l. Chromium was separated from iron by anion exchange and determined spectrophotometrically using diphenylcarbazide. The method showed a precision of ±0.02 μg Cr/1. Chromium occurs in sea water in the 3+ oxidation state.     

Study of interference in the flame atomic absorption spectrometric determination of lithium by using factorial design

The severe interference of a number of metallic ions found in brines, marine sediments and sea water in the determination of lithium is demonstrated. Calcium, iron and sodium significantly depressed the absorption signal on lithium in an air/acetylene flame. Aluminium, magnesium and strontium up to 1500, 1000 and 200 μg/mL, respectively, showed no interference in the determination of lithium under the same conditions. Potassium produced some suppression of the lithium signal at levels in excess of 1500 μg/mL. Experimental data were examined using the factorial design method. Interference was demonstrated in two synthetic samples (models of “brine” and “marine sediments” ) and natural marine sediment. It was possible to eliminate all interferences using a higher temperature (nitrous oxide/acetylene flame). In addition, by using the standard addition method the interference disappeared, which confirmed the interference as a proportional systematic error.     

Determination of tungsten in silicates and natural waters

Coprecipitation with hydrous manganese dioxide is used for the concentration of tungsten from natural waters (including sea water) and from solutions prepared from silicate rocks and sediments by hydrofluoric acid attack. After dissolution of the hydrous manganese dioxide precipitate in acidified sulphur dioxide solution, cation excliange is used to separate tungsten and molybdenum from other coprecipitated elements, hydrogen peroxide being used as eluant. Molybdenum is separated from tungsten by extraction of its dithiol complex from 24 N hydrochloric acid medium containing citric acid and can be determined photometrically. After destruction of citric acid, tungsten is determined photometrically with dithiol. The overall cliemical yield of th analytical process is 94±1%. The standard deviation of the method is ±0.010 μg for sea water (0.116 μg W/l) and ca 0.05 μg/g for siliceous sediments containing 0.5–1.0 μg W/g.     

Determination of Cu, Zn and Cd in water by FAAS after preconcentration by baker’s yeast (Saccharomyces cerevisiae) immobilized on sepiolite

By using the adsorbent Saccharomyces cerevisiae immobilized on sepiolite an adsorption-elution method was developed for the preconcentration of Cu, Zn, and Cd followed by flame atomic absorption spectrometry (FAAS). Recoveries were 98.3 ± 0.4% for Cu, 94.2 ± 0.3% for Zn, and 99.04 ± 0.04% for Cd at 95% confidence level obtained by the column method. The influence of sea water matrix elements on the separation of the trace elements was also assessed by using the column procedure. The breakthrough capacities were found to be 74 μmol/g for copper, 128 μmol/g for zinc and 97 μmol/g for cadmium. After optimization the proposed method was applied to the trace metal determination in sea and river water.     

ICP-AES内标法测定钢铁及其合金样品中的化学成分

建立了内标法测定钢铁样品中化学成分的ICP-OES分析方法。利用铟元素作为内标物质,消除了铁基体元素对被测元素的干扰,减少了废气、废液的产生。钢铁样品中16种被测元素的检测范围在0．001％-20．00％之间,检出限为0．001-0．030μg／mL,回收率为97％-110％。该方法减少了高纯物质的使用。     

The determination of bismuth in sea and natural waters

A spectrophotometric method is described for the determination of bismuth in natural waters, particularly sea water at the level of ca. 0.02 μg/l. The element is concentrated from the acidified sample, by sorption onto De-Acidite FF anion exchanger, eluted with nitric acid and determined photometrically with dithizone. The overall efficiency of the separation process was determined radiochemically and amounted to ca. 85%. The interference of elements also taken up in the ion-exchange process was negligible at their normal levels in natural waters. A deep water sample from the North Atlantic was found to contain 0.015μg Bi/l.     

火焰原子吸收光谱法分析猫爪草胶囊中铁锌锰的含量

为给猫爪草胶囊药用研究提供依据,采用空气-火焰原子吸收光谱法对猫爪草胶囊中铁锌锰元素的含量进行了测定.结果表明,猫爪草胶囊中,铁为287.8 μg/g,锌为27.4 μg/g,锰为24.6 μg/g.方法精密度为2.67%～4.09%,各元素回收率在96.3%～107.6%之间.该法操作简单、结果准确,是猫爪草胶囊中铁...     

离子色谱法测定南海海水中的硝酸盐和磷酸盐及其对地球化学意义的初探

根据2010年"西太平洋海域海洋灾害对气候变化的响应"航次,从南海海域选取E断面4000m水深全层次站位,采用氧化银沉淀法,结合免化学试剂离子色谱技术分析了该站海水中的NO-3-N、PO3-4-P,NO-3、PO43-的检出限分别为4.84和17.1μg/L,回收率分别为94.5%和101.2%,相对标准偏差(RSD)分别为0.27%和0.15%,结果令人满意。并对其地球化学意义进行了初步分析探讨,为南海及周边海域海洋环境的研究提供了基础数据。     

Electrothermal Atomic Absorption Spectrometric Determination of Cobalt,Copper and Nickel in Fresh Water After Their Preconcentration by Precipitate Flotation

Abstract

A method is developed for simultaneous separation and determination of μg/L levels of Co(II), Cu(II) and Ni(II) in fresh water by precipitate flotation. The optimal conditions of the experimental procedure with hydrated iron(III) oxide and iron(III) tetramethylenedithiocarbamate as collectors were investigated. The pH interval of the working medium, within which Co(II), Cu(II) and Ni(II) can be successfully separated, was determined from the aspect of collectors and surfactant stability. The amounts of the elements investigated were determined by electrothermal atomic absorption spectrometry. The detection limit of the method is 0.15 μg/L for cobalt, 0.03 μg/L for copper and 0.79 μg/L for nickel.     

The sesquiterpenes β-caryophyllene and caryophyllene oxide isolated from Senecio salignus act as phytogrowth and photosynthesis inhibitors

The n-hexane extract of S. salignus plants inhibited ATP synthesis and two sesquiterpenes, the β-caryophyllene (1) and caryophyllene oxide (2) were isolated from this nonpolar fraction. Compound 1 inhibited by 42% the root elongation of Physalis ixocarpa seedlings at 50 μg/mL and by 53% at 150 μg/mL, whereas at 150 μg/mL this compound only inhibited root elongation of Echinochloa crus-galli by 30%. On the other hand, compound 2 had no effect on either germination or root and stem growth of E. cruss galli and P. ixocarpa. However, 1 and 2 inhibited the dry biomass of P. ixocarpa plants grown for 18 days previous to treatment and it was found that 1 was the most active biomass inhibitor. The Chl a fluorescence transient in vivo experiment indicates that 1 (100 μg/mL) has a major effect at 72 h after treatment on leaves of P. ixocarpa plants by inhibiting photosystem II (PS II) transforming active reaction centers to "heat sinks" or the formation of silent reaction centers unable to reduce Q(A). β-Caryophyllene also induces chlorosis on treated leaves.     

The determination of antimony in natural waters with particular reference to sea water

A procedure is described for the determination of antimony in natural waters at concentrations down to 0.1 μg/l or less. The element is concentrated by coprecipitation with hydrous manganese dioxide (produced by the reaction of permanganate with ethanol). It is separated from manganese, iron and interfering elements by extraction from 5 M sulphuric acid, 0.01 M with respect to iodide, using methyl isobutyl ketone. After back-extraction with 0.4 M hydrochloric acid, it is determined photometrically using rhodamine B. The overall chemical yield of the process is measured radiochemically and amounts to ca. 80%. Sea water samples from the Irish Sea were found to contain 0.13–0.40 μg Sb/l.     

信宜市教育城幼儿园幼儿微量元素营养评估及分析

为了对信宜市教育城幼儿园幼儿微量元素营养进行评估,共采集了教育城幼儿园幼儿239例头发,其中男165例,女74例,用电感耦合等离子体发射光谱法测定头发中的钙、锌、铁、铜、锰和铅的含量,其结果分别为：钙584．844-178．76μg/g,锌178．10±83．38μg/g,铁61．67±17．49μg／g,铜14．03±8．92μg／g,锰2．86±1．73μg／g,铅7．13±2．83μg／g。按照世界卫生组织的四级评估标准进行评估,钙、锌和锰等元素没有发现中度以上的营养缺乏现象,其中铁只有0．4％重度营养缺乏,铜只有8．0％中度营养缺乏,有害元素铅没有发现中度以上超标现象。比对结果,信宜市教育城幼儿园幼儿微量元素营养水平,远优于当地及周边城市的幼儿园幼儿。幼儿园幼儿微量元素营养是否均衡,应作为幼儿园总体评估指标之一。     

QuEChERS结合LC-MS/MS同时测定虾肉中72种兽药残留

建立了虾肉中72种兽药残留的QuEChERS结合液相色谱串联质谱测定的分析方法。样品经5%醋酸乙腈均质提取离心后,上清液依次用C18净化、乙腈沉淀蛋白、氮吹浓缩,0.1%甲酸-乙腈（4∶1,体积比）定容,0.22 μm滤膜过滤,LC-MS/MS测定,外标法定量。流动相为0.1%甲酸和乙腈,色谱柱为ZORBAX SB-C18,采用梯度洗脱模式进行色谱分离;离子源为电喷雾离子源（ESI）,多重反应监测模式（MRM）。在0.1~1 840 μg/kg范围内,97.2%的目标兽药的线性相关系数大于0.95,定量下限范围为0.02~33.58 μg/kg。除熊脱氧胆酸、头孢吡啉、头孢喹咪、头孢噻呋、林可霉素、二嗪哝的回收率为38%~58%外,其它目标化合物的回收率为61%~119%,相对标准偏差为1.6%~20%,满足各国的限量法规要求。对市售的海虾、凤尾虾仁、青虾仁样品进行72种兽药残留筛查测定,海虾和凤尾虾仁中无检出;青虾仁样品中检出磺胺嘧啶和磺胺甲唑,检出量分别为4.0 μg/kg和2.2 μg/kg,均低于各国规定的限量要求。     

Determination of chlorobenzenes in pure,tap, and sea water by static headspace gas chromatography‐electron capture detection

A simple, efficient, solvent‐free, and commercial readily available approach for determination of 11 chlorobenzenes (CBs) in water samples using the static headspace (HS) sampling and gas chromatography‐electron capture detector has been described. The proposed static HS sampling method was initially optimized and the optimum experimental conditions found were 10 mL water sample containing 20% (w/v) sodium chloride placed in a 20 mL vial and stirred at 70°C for 30 min. The linearity of the method ranged from 0.16 to 8.0 μg/L for dichlorobenzene isomers, 0.0176～0.88 μg/L for trichlorobenzene isomers, 0.004～0.2 μg/L for tetrachlorobenzene isomers, and from 0.001 to 0.05 μg/L for pentachlorobenzene and hexachlorobenzene, with correlation coefficients ranging between 0.9992 and 0.9999. The limits of detection were in the low μg/L level, ranging between 0.0002 and 0.04 μg/L. The relative recoveries of spiked CBs with external calibration or standard addition method at different concentration levels in pure, tap, and sea water samples were 83～116%, 89～108%, and 93～112%, respectively, and with relative standard deviations of 1.9～6.3%, 1.6～5.4%, and 2.5～5.7% (n = 5), respectively. It is concluded that this method can be successfully applied for the determination of CBs in pure, tap, and sea water samples.     

The simultaneous determination of vanadium,chromium, manganese,iron, cobalt,nickel, copper and zinc in sea water by x-ray fluorescence sectrometry

A procedure is described for the determination of microgram quantities of the elements vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc in sea water. Separation and concentration of these elements from a large salt matrix, in order to prevent interferences in the subsequent X-ray fluorescence spectrometry, is achieved by continuous solvent extraction. Ammonium pyrrolidine dithiocarbamate is used as a chelating agent, and the chelated trace elements are quantitatively extracted at a pH of ca. 2.5 into methyl isobutyl ketone. Detection limits of 0.14 μg or better are obtained when a 600-sec counting period is used for X-ray fluorescence spectrometry.     

The separation of mercury from sea water by adsorption colloid flotation and analysis by flameless atomic absorption

Adsorption colloid flotation has been found capable of separating ionic mercury from sea water quantitatively at levels as low as 0.02 μg l^?1 with use of a cadmium sulfide collector and octadecyltrimethylammonium chloride as the surfactant. The mercury in 25 samples can be separated in 2 h. Following the separation the mercury was analyzed by flameless atomic absorption. Recovery of mercury from 0.5 l samples spiked with 0.010 μg of inorganic mercury gave sol|0.014 ± 0.002 μg/0.5 l. Black Point, Oahu near-shore sea water was found to contain mercury in the range 0.038–0.078 μg l^?1 with no measurable organic mercury fraction. Sea-water samples collected at an open ocean station analyzed for total mercury revealed the highest mercury concentrations above 200 meters. Mercury concentrations in general showed a decreasing trend with increase in depth.     

Certification of the methylmercury content in SRM 2977 Mussel Tissue (organic contaminants and trace elements) and SRM 1566b Oyster Tissue

The methylmercury content in two new marine bivalve mollusk tissue Standard Reference Materials (SRMs) has been certified using results of analyses from the National Institute of Standards and Technology (NIST) and two other laboratories. The certified concentrations of methylmercury were established based on the results from four and six different (independent) analytical methods, respectively, for SRM 1566b Oyster Tissue (13.2 ± 0.7 μg/kg) and SRM 2977 Mussel Tissue (organic contaminants and trace elements) (36.2 ± 1.7 μg/kg). The certified concentration of methylmercury in SRM 1566b is among the lowest in any certified reference material (CRM).     

西班牙Quinton海洋水生命元素测定及功能评价

目的应用电感耦合等离体子质谱(ICP-MS)检测法测定西班牙Quinton海洋水中的生命元素(该文特指人体所需的宏量元素和微量元素)。方法建立电感耦合等离子体质谱(ICPMS)法同时测定Quinton海洋水中21种生命元素含量的分析方法。结果方法检出限为0.01~0.10μg/mL,元素加标回收率为94.12%~104.35%,相对标准偏差为0.3%~12.2%。结论方法简单、快速、准确,适用于海洋水中多元素含量同时测定。并用元素含量评价Quinton海洋水的特性和功能。