Determination of sulphur in uranium matrix by total reflection X-ray fluorescence spectrometry

The possibility of sulphur determination in uranium matrix by total reflection x-ray fluorescence spectrometry (TXRF) has been studied. Calibration solutions and samples of sulphur in uranium matrix were prepared by mixing uranium in form of a standard uranyl nitrate solution and sulphur in the form of Na₂SO₄ standard solution, prepared by dissolving Na₂SO₄ in Milli-Q water. For major element analysis of sulphur, it was determined without separation of uranium whereas for the trace level determinations, uranium was first separated by solvent extraction using 30% tri-n-butyl phosphate (TBP) in dodecane as an extractant. In order to countercheck the TXRF results, a few samples of Rb₂U(SO₄)₃, a chemical assay standard for uranium, were diluted to different dilutions and sulphur content in these solutions were determined. The TXRF determined results for trace determinations of sulphur in these diluted solutions were counterchecked after addition of another uranium solution, so that sulphur is at trace level compared to uranium, separating uranium from these solution mixtures using TBP extraction and determining sulphur in aqueous phase by TXRF. For such TXRF determinations, Co was used as internal standard and W Lα was used as excitation source. The precision and accuracy of the method was assessed for trace and major element determinations and was found to be better than 8% (1σ RSD) and 15% at a concentration level of 1 μg/mL of sulphur measured in solutions whereas for Rb₂U(SO₄)₃, these values were found to be better than 4 and 13%, respectively.     

A sensor based on electrodes supported on ion-exchange membranes for the flow-injection monitoring of sulphur dioxide in wines and grape juices

A sensitive and fast responding electrochemical sensor is described for the determination of free and total sulphur dioxide in wines and grape juices which prevents interferences coming from ethanol and other natural components. It consists of a cell provided with a porous gold working electrode supported on one face of an ion-exchange membrane, acting as a solid polymer electrolyte (SPE), which allows gaseous electroactive analytes to be detected. This sensor was used as an amperometric detector for a flow injection system in which controlled volumes of headspace equilibrated with samples were injected. This approach was adopted to make also possible the determination of total SO₂, avoiding drawbacks caused by the high relative humidity generated by the sample heating resulting from the neutralization reaction of excess NaOH, whose addition was required to release sulphur dioxide from its combined forms. Factors affecting the detection process were examined and optimised. Under the identified optimal conditions, SO₂ detection resulted in sharp peaks which allowed to infer detection limits for a signal-to-noise ratio of 3, referred to liquid samples, of 0.04 and 0.02 mg L⁻¹ for free and total SO₂ which were determined at 20 and 35 °C, respectively. Moreover, the responses were found to be characterized by good repeatability (±2% and ±4%, respectively) and linear dependence on the SO₂ concentration over a wide range (0.2-500 mg L⁻¹ for both free and total SO₂). Finally, the long-term stability of the sensor turned out to be totally satisfactory in that responses changed of ±9% alone even after long periods of continuous use. The application to some commercial wines and grape juices is also presented.     

Determination of sulphur dioxide in young white wines by flow injection with chemiluminescence detection

The use of the closed-flow injection system for the direct and repetitive determination of sulphur dioxide (5.0–300 mg l^t?1 in young white wines with chemiluminescence detection is described. The chemiluminescence from the oxidation of the disulfitomecurate complex with cerium(IV) in an acidic solution in the presence of riboflavin sulphate. The procedure is simple and reproducible. Results are in good agreement with those obtained by the spcetrophotometric pararosaniline method.     

空气-氩气冷却ICP-AES测定环烷酸镍中的镍、铁、镁和钙

本文介绍采用空气-氩气冷却ICP直接测定了以甲基异丁基酮稀释的环烷酸镍溶液中部分金属的含量。并研究了方法的工作条件、检出限和乙醇的影响。本法快速简便,结果令人满意。     

ICP-AES法测定钢中的铈

建立了离子体发射光谱仪测定钢中铈元素的方法。为消除共存元素对铈分析游线的光谱干扰,选择Ce413．380nm作为分析线,铈含量在0．005％-0．50％之间工作曲线线性良好。对于含量范围在0．005％-0．10％的铈元素,回收率为85．6％-12．5％,测定结果的相对标准偏差小于9．74％（n=8）;对于含量范围在0．10％-0．50％的铈元素,回收率为99．5％-103．0％,测定结果的相对标准偏差小于3．52％（n=8）。该方法适宜钢中含量范围在O．005％-0．50％的铈元素的测定。     

高性能球型氢氧化亚镍的ICP-OES分析方法

建立了镍氢电池正极材料氢氧化亚镍中主成分锌、钴及杂质钙、镁、锰、镉的ICP AES测定方法。选择了仪器最佳工作条件 ,研究了镍基体对被测元素的干扰。方法的回收率为 95 .9%～ 1 0 3% ,RSD为 0 .93%～ 1 8%。     

Volatile sulphur compounds in wines related to yeast metabolism and nitrogen composition of grape musts

The influence of nitrogen compounds in grape musts on the content of sulphur compounds of wines was studied. Different vinifications were performed with the addition of methionine (20 mg l⁻¹) and/or cysteine (40 mg l⁻¹) to grape musts before alcoholic fermentation. Six grape musts, with different nitrogen composition, from cultivars of the ‘Vinhos Verdes’ Region, in Portugal, were used. Addition of methionine to grape musts enhanced the content of wines in 3-(methylthio)-1-propanol, acetic acid-3-(methylthio)propyl ester, 3-(methylthio)propionic acid and some unidentified sulphur compounds. Increase of cysteine concentration in musts led to the production of wines with high levels of hydrogen sulphide and cis-2-methyltetrahydro-thiophene-3-OL and also unidentified sulphur compounds; however, the content of 3-(methylthio)propionic acid in the wines decreased considerately with the addition of cysteine to grape musts. This work showed that cultivars from the Vinho Verde Region show different sulphur compound contents. Avesso wines, elaborated from grape musts with low amino acids level, presented the highest total sulphur compounds content. Wines from Azal branco and Alvarinho were characterised by high contents of 4-(methylthio)-1-butanol and 3-(methylthio)propionic acid, respectively. A high content of N-(3-(methylthio) propyl)-acetamide and dimethylsulphone characterise the Loureiro wines. In contrast, Trajadura wines, produced from a must rich in amino acids, presented a low total sulphur compounds content; however, these wines were also characterised by high concentrations of 4-(methylthio)-1-butanol, acetic acid-3-(methylthio)propyl ester and hydrogen sulphide.     

ICP-AES法同时测定化妆品中的Hg、As、Pb

采用高压溶样弹，将样品用硝酸－过氧化氢或高氯酸－过氧化氢溶解后，用ＩＣＰ－ＡＥＳ法对汞砷铅连续测定。方法的回收率分别为８６．０％、９６．２％、９９．８％，变异系数分别为３．１７％、２．５１％、２．０１％。与原子吸收法比较，无显著差异。应用于市售化妆品检测，结果满意。     

Solubility of sulphur dioxide in aqueous electrolyte solutions at higher ionic strengths—Chloride and bromide containing systems

The absorption of sulphur dioxide in chloride and bromide containing electrolyte solutions was measured up to ionic strengths of 5 mol/dm³. The thermodynamic equilibrium of the gas phase and the liquid phase was characterized by UV spectroscopy. UV spectra analysis gave strong evidence for SO₂X⁻ complexes existing in the solutions. Consequently, these compounds were implemented in the reaction scheme for absorption.     

四苯硼钠沉淀-ICP 发射光谱法间接测定药物片剂中扑尔敏含量

研究了等离子体发射光谱法间接测定药物片剂中扑尔敏的含量。选择了沉淀条件及ＩＣＰ－ＡＥＳ测定的最佳条件。在ＰＨ２－４．５范围内,当四苯硼钠过量时可完全沉淀扑尔敏。硝酸铝可以使沉淀导速如凝而易于过滤,测定滤液中的四苯硼钠计算得扑尔敏的含量。方法的相对标准偏差为２．２％回收率为９９％－１０２％,已用于实际样品的分析。     

Determination of sulphur in petroleum products after sulphur dioxide generation and of sulphur dioxide in air by chemiluminescent flame emission

The determination of sulphur in petroleum products by combustion, concentration of the sulphur dioxide in sodium tetrachtoromercurate solutions and cool flame molecular emission is described. Improvements in burner design and optimization of analytical conditions result in a minimum detectable amount of 6 ng of sulphur. The absorption of sulphur dioxide from air samples and its determination by a similar method gives a detection limit of 1.3 μg SO₂ m^-3.     

Determination and fractionation of sulphur in a contaminated dredged sediment

Conversion of sulphur compounds in reduced, contaminated sediments that are brought in upland conditions may largely affect the potential mobility of heavy metal contaminants. We applied selected methods for the determination of total sulphur and sulphur fractions in a contaminated sediment in the reduced state and after gradual drying and oxidation during 1 month. Dry ashing, followed by ion chromatographic detection, was reliable for the determination of total sulphur. Good recoveries were obtained in both reference samples and spiked samples. Total sulphur was 14.5±0.6 g kg⁻¹ relative to dry sediment. Wet chemical methods that involve the determination of acid-volatile, Zn–HCl-reducible, chromium-reducible, acetone-soluble and HI-reducible sulphur were used to estimate specific sulphur forms. Results for acetone-soluble sulphur were to high and not consistent with results for other fractions. Major part of sulphur in the sediment (90%) was inorganic. Sulphides were converted partially to sulphate and to intermediary oxidised sulphur compounds upon oxidation of the sediment. The results suggested that the intermediary oxidised sulphur pool in the reduced sediment (2.5 g kg⁻¹) mainly consisted of pyrite, that was not converted during drying and oxidation. No significant changes in organic sulphur were detected.     

萃取分离 ICP-AES 法测定含铪铀中微量杂质元素

用盐酸-硝酸-氢氟酸溶解含铪的铀试样,以磷酸三丁酯为萃取剂,分离铀、铪与待测杂质元素.用 ICP-AES 法同时测定了试样中钼、钨、铁、硼、锰、铍、铜、镁、钙、铝和镍等11种杂质元素的含量.将 0.0900 g～0.1100 g 试样制成 6 mL 溶液时,各杂质元素测量范围为 1.0×10-3%～1.0×10-1%,回收率在 94%～105% 之间,相对标准偏差优于 10%.     

ICP-AES法同时测定合金工具钢中的Cr、Mo、V

采用盐酸－硫酸对以Cr,Mo,V为主要合金元素的工具钢试样进行消化,用ICP－AES法同时测定试样中Cr,Mo,V的含量。方法简便,结果满意。方法的加标回收率为95．5％－103．2％,相对标准偏差（n=9)为1．61％－6．64％。     

微色谱柱分离/ICP-AES测定环境样品中的痕量硼

本文采用色谱系统对水样品（温泉水、卤水）中的硼进行分离富集，探讨了影响其分离富集的条件。实验表明，在pH＝8条件下，硼可被树脂完全吸附，用3mL 1mol/L硫酸可以从吸附术上完全解吸硼，浓缩物用ICP－AES进行测定，所建立的方法简便、准确，适合于含盐量高及其它水样品中微量硼的测定。     

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。     

ICP-AES测定陶瓷器皿中微量溶出铅、镉的研究

用4%乙酸溶液萃取分离日用瓷表面微量溶出元素Pb和Cd后,采用电感耦合等离子体原子发射光谱(ICP-AES)法进行了分析,对影响其测量的各种因素进行了较详细的研究,确定了实验的最佳测定条件。结果表明,方法的检出限为0.023(Pb)和0.006μg/L(Cd),回收率为98.0%~104.0%,RSD小于3.5%。该法准确、快速、简便,应用于日用瓷中的微量溶出铅、镉的测定,结果满意。     

ICP-OES 法测定高温合金中的多种化学成分

采用电感耦合等离子体光谱法（ICP－OES）测定了镍基高温合金中的Zr、Mo、W、Ta、Nb、Ti等多种化学成分。选择仪器最佳工作条件,研究了镍基体对被测元素的影响。方法的回收率为95．3％－102％,RSD为0．40％－1．7％。     

用ICP-AES法测定首饰金的成分

本文报道采用ICP-AES法直接同时测定首饰金中合金无素及主要杂质元素含量,通过计算求得金含量。确定了仪器的最佳工作条件,进行了干扰试验。方法适用于18k～99.99%成色的首饰金。测定的RSD为<0.01%(对于高纯度金祥n=10)～0.2%(对于10k金样n=10)之间,分析结果表明,方法准确、快速、简便且样品消耗量少。