Determination of calcium, magnesium and zinc in unused lubricating oils by atomic absorption spectroscopy

Varying concentrations of lanthanum and strontium were added to solutions of ashed unused lubricating oils for the determination of calcium, magnesium and zinc content using flame atomic absorption spectrophotometry. At least 3000 μg g⁻¹ of lanthanum or strontium was required to completely overcome the interference of the phosphate ion, PO³⁻₄, and give peak values for calcium. The presence of lanthanum or strontium did not cause an appreciable increase in the amount of magnesium and zinc obtained from the analyses. The method is fast and reproducible, and the coefficients of variation calculated for the elements using one of the samples were 1.6% for calcium, 3.5% for magnesium and 0.2% for zinc. Results obtained by this method were better than those obtained by other methods for the same samples.     

Fast determination of calcium, magnesium and zinc in honey using continuous flow flame atomic absorption spectrometry

A procedure is described for the rapid determination of calcium, magnesium and zinc in honey with no previous mineralization stage. The samples are dissolved in a solution containing dilute hydrochloric acid and a lanthanum salt, and then directly introduced into the flame atomic absorption spectrometer by means of a simple continuous-flow manifold. The computer-controlled system performs an automatic on-line dilution of the solutions, in this way decreasing matrix effects due to the organic matter content and allowing analytical signals within the linear response range to be obtained. Calibration is carried out against aqueous standards. Reproducibilities for calcium and magnesium measurements in the honey samples are close to +/-3%. The detection limit for zinc is 0.2 mug g(-1), the reproducibility obtained for a honey sample containing 1.7 mug g(-1) zinc being +/-5.2%. The results agree with those obtained by means of a lengthy mineralization-based procedure, the main advantages of the non-conventional methodology reported being automation, saving of time and a decrease in the contamination risk.     

Direct FIA-AS determination of potassium and magnesium in cement samples by use of the slurries approach

A direct procedure has been developed for the flame atomic determination of potassium and magnesium in cement samples. A 50-mg sample is dispersed in 25 ml of 0.13M nitric acid; 100 mul of this slurry is injected in a double channel FIA manifold simultaneously with 100 mul of a 10% (w/v) lanthanum solution. This procedure allows the rapid extraction of potassium and magnesium by leaching of the sample; nitric acid is not necessary if only potassium must be determined and the sample can be diluted with only distilled water. Aqueous standards are used. The manifold employed includes a well-stirred mixing chamber, which provides an adequate on-line dilution of the sample, in order to obtain emission or absorbance measurements in the dynamic range of the elements to be determined. The results obtained in the analysis of real samples agree with those found by flame atomic spectrometry after a previous alkaline fusion with lithium carbonate, and exhibit better precision. The limit of detection of the procedure is 0.007% for K(2)O and 0.01% for MgO and the precision of the entire procedure corresponds to a relative standard deviation of 1%.     

The determination of wear metals in used lubricating oils by flame atomic absorption spectrometry using sulphanilic acid as ashing agent

A simple and reliable ashing procedure is proposed for the preparation of used lubricating oil samples for the determination of calcium, magnesium, zinc, iron, chromium and nickel by flame atomic absorption spectrometry. Sulphanilic acid was added to oil samples and the mixture coked and the coke ashed at 550 degrees C. The solutions of the ash were analysed by flame AAS for the metals. The release of calcium, zinc, iron and chromium was improved by the addition of sulphanilic acid to samples. The relative standard deviations of metal concentration results in the initial oil samples were 1.5% for Ca (1500 mg l(-1) level), 0.3% for Mg (100 mg l(-1) level), 3.1% for Zn (1500 mg l(-1) level), 0.7% for Fe (500 mg l(-1) level), 0.02% for Cr (50 mg l(-1) level) and 0.002% for Ni (10 mg l(-1) level). The optimum sample size for efficient metal release was 20 g while the optimum sulphanilic acid to oil ratio was 0.05 g per gram of oil for Zn and Cr and 0.10 g for Ca and Fe. Results obtained by this procedure were highly reproducible and comparable with those obtained for the same samples using standard procedures.     

The determination of strontium in coal ash by atomic absorption spectrophotometry

An atomic absorption spectrophotometric method for the determination of 0.01%–0.40% strontium in coal ashes is proposed. After suitable dissolution of the sample, 2000 p.p.m. of lanthanum are added to overcome interferences before the solution is atomized. The results obtained were compared with those obtained by flame-emission spectrophotometry. The method is rapid and no preliminary separations are necessary.     

Determination of tributyltin in toluene extract from sea water by graphite furnace atomic absorption spectrometry with a new matrix modifier

A new matrix modifier composed of calcium and chromium[VI] was proposed for the determination of tributyltin (TBT) in toluene extract from sea water containing sediment by graphite furnace atomic absorption spectrometry (GFAAS). Fourteen inorganic and organic compounds (barium, calcium, chromium[VI], lanthanum, magnesium, nickel, palladium, strontium, calcium-chromium[VI], calcium-strontium, nickel isocaprylate, 5%-, 10%-aqueous solution of ascorbic acid and toluene-saturated solution of ascorbic acid) as a matrix modifier were comparatively studied and a matrix modifier composed from 5 microg of calcium and 1 microg of chromium[VI] was found to give the best performance. The interference effects of co-existing elements in sea water containing sediment (aluminium, iron, magnesium, sodium and strontium) were studied. TBT in eight toluene extracts was determined by GFAAS with the proposed matrix modifier. The relative standard deviation was 3.0% for 63 ng ml(-1) of TBT (n = 11). The recoveries were 88-104%. The characteristic mass was 7 pg. The linearity range was 0-250 ng mg(-1).     

进口氧化皮化学特性及X射线荧光光谱分析

采用玻璃片法熔融进口氧化皮样品,并应用X射线荧光光谱法测定其中全铁和硅、铝、磷、钙、镁、钛、砷、铅等15种杂质元素的含量.根据氧化皮成分含量范围,利用多个铁矿石标准样品、部分标准样品添加基准物质Fe2O3配制系列校准物质,建立工作曲线.结果表明,该方法能准确、快速地对氧化皮进行分析,测量值与经典方法或标准值比较没有显著性差异.     

再生障碍性贫血患者中药治疗前后微量元素变化初步观察

对20例再生障碍性贫血患者（以下简称再障）头发中12种微量元素的含量进行测定，与正常人做对照，结果发现，阴虚型患者锂、钙、锶、铬显著减少，阴虚型患者锌、镁、钡、钙、锂明显下降，阴阳俱虚型患者则12种元素均减少，并对本院治疗再障贫血的24味中药的微量元素的含量也进行测定。结合微量元素变化对指导再障的辩证组方和辩证施治提供新的思路，同时系统观察再障贫血10例治疗前后微量元素的变化情况，从微量元素角度探求再障的发症因素，认为与部分微量元素缺乏有关，补充相关的微量元素，再障患者可恢复健康。     

血清铁、锌、钙、镁、磷与妊娠的关系探讨

为探讨血清铁、锌、钙、镁、磷在孕妇体内的水平，做好围产期孕妇的保健工作，提高孕产妇的健康水平和新生儿健康素质，抽取125例孕中期妇女空腹静脉血，采用透射比浊法测定了其血清铁、锌、钙、镁、磷的含量。结果表明，铁、锌、钙、镁、磷的异常在孕妇中有一定的发生率，其中尤以钙与锌的缺乏最为多见。提示应定期检测孕妇血清铁、锌、钙、镁、磷水平，并采取相府的防治措施．以提高孕产妇及新生儿的健康水平。     

Determination of strontium in human tooth enamel by atomic absorption spectrometry

Interferences in the atomic absorption of strontium by calcium and phosphate at the levels found in human tooth enamel were investigated for both air-acetylene and nitrous oxide-acetylene flames. In air-acetylene flames, the interferences can be reduced by the addition of lanthanum(III); but perchloric acid, used for sample dissolution, causes a significant reduction in the calcium-phosphate interference, so that a standard addition method can be applied, without the need for any chemical separations. An average recovery of 98.6% for added amounts of strontium to enamel showed the proposed method to be reliable.     

Direct determination of calcium,copper, iron,magnesium, manganese and zinc in amniotic fluid samples using inductively coupled plasma-atomic emission spectrometry

An inductively coupled plasma-atomic emission spectrometric method is reported for the determination of calcium, copper, iron, manganese, magnesium and zinc. Samples are introduced directly when a sheath gas device is used. An external calibration procedure is used. The standards are prepared in a matrix composed of 0.5% (w/v) albumin and 0.76% (w/v) sodium chloride. The procedure was evaluated with a standard reference material (NBS SRM 909 Human Serum); all the values obtained are in agreement with the certified values. Results obtained for the determination of zinc, calcium, magnesium, copper, iron and manganese in amniotic fluid samples are reported.     

1152例婴儿血中6种元素检测结果的分析

为探讨婴儿体内铜、锌、钙、镁、铁和铅微量元素的含量及其与年龄、性别的关系,测定了1 152例湖南长沙地区1岁内婴儿指末梢全血中6种元素铜、锌、钙、镁、铁和铅的含量,对其结果进行了统计分析。结果表明,所测婴儿元素铁、锌缺乏最显著,其次是钙缺乏;铜、镁无明显失衡;血铅超标的水平较低;不同性别之间6种元素含量的差异无统计学意义。提示在长沙地区的孕婴保健中,应加强锌、钙与铁的合理补充。     

西安市老年人末梢血铜、锌、铁、镁、钙元素含量分析

为调查60岁以上老年人体内微量元素及钙、镁的含量,采用原子吸收光谱法对西安市60岁以上的老年人末梢血中的铜、锌、铁、镁、钙的含量进行了测定,观察了5元素的缺乏率及随年龄的增长5元素的缺乏情况.结果表明,60岁以上老年人,元素过量的情况鲜见;铜、锌、铁、镁、钙的缺乏率分别为37.87%0,11.76%,21.51%,2....     

中药牛大力微量元素含量的测定

用电感耦合等离子体发射光谱仪(ICP)测定了湛江地区产的中药牛大力微量元素的含量,发现其Ca、Mg、Fe、Zn等元素的含量都比较丰富,相对标准偏差为0.32%~7.05%,回收率为93.0%~101%,结果令人满意。     

地胆头微量元素含量的测定

用电感耦合等离子体发射光谱仪(ICP)测定了湛江地区产的中药地胆头微量元素的含量,发现其钙、镁、铁、锌等元素的含量都比较丰富。数据显示相对标准偏差为0.22%~4.45%,回收率为96.0%~102.0%,结果令人满意。     

微波消解－ICP-OES测定钛渣中常量或微量杂质

钛渣样品采取高压密闭微波加热方式以HF、HNO3进行消解,采用电感耦合等离子体原子发射光谱法(ICP-OES)直接同时测定常量、微量杂质铁、铅、砷、铬、铜、磷、锰、钒、镁、钙。考察了消解条件、基体钛以及共存元素之间的干扰影响、等离子体参数等测定条件,通过优选元素分析谱线、以及采用基体匹配与同步背景校正相结合的方式消除光谱干扰和基体效应。测定50、60、70、80、90等不同品位钛渣中杂质元素的结果表明:方法检测范围涵盖了0.005%～10.0%的钙、镁、铁,以及0.005%～2.0%的铅、砷、铬、铜、磷、锰、钒,校准曲线相关系数大于0.999 2;背景等效浓度0.002%～0.0015%,检测限0.0009～0.0038%;含量不小于1.0%的RSD低于0.677%,在0.010%～0.10%含量范围内RSD低于3.85%;回收率为90.0%～108.0%。以本法对70、80、90 3个高钛渣标准样品的定值分析结果与传统化学方法对照一致。     

镧助剂对模拟生物沼气重整制备合成气中Ni/SBA-15催化剂结构和性能的影响

以介孔分子筛SBA-15为载体, 采用浸渍法制备了镍质量分数(w)为12.5%, 并且分别添加质量分数(w)为2.5%的镧、铈、镁、钙、锶等助剂的系列Ni基催化剂. 以CH4/CO2体积比为2:1的模拟生物沼气和适量氧气作为原料气, 在常压固定床反应器上评价了催化剂对模拟生物沼气重整制合成气的反应性能. 采用X射线粉末衍射(XRD)、N2吸附/脱附、透射电子显微镜(TEM)、X射线光电子能谱(XPS)及H2程序升温还原(H2-TPR)等对催化剂的结构进行了表征. 催化活性评价显示, 添加镧助剂的2.5%La/12.5%Ni/SBA-15催化剂比添加铈、镁、钙、锶等助剂的催化剂具有更高的催化活性, 并且具有很好的稳定性. 因此, 文中着重研究了镧助剂对催化剂结构和模拟生物沼气重整制合成气的反应性能的影响. 结果表明, 镧能明显提高Ni/SBA-15催化剂的表面镍含量, 同时还具有很好的抗积炭作用, 在850 ℃的温度下反应820 h没有发现积炭生成, 这些可能是提高催化剂性能和稳定性的重要因素.     

茅根微量元素含量的测定

用电感耦合等离子体发射光谱仪（ICP）测定了湛江地区产的中药茅根微量元素的含量。结果表明,其钙、镁、铁、锌等元素的含量都比较丰富,测定方法的相对标准偏差为0．12％～4．03％,回收率为97．0％～102．0％,本法简便、快速,具有较高的准确性和重现性,适用于实际分析。     

微波等离子体炬原子发射光谱法测定铁增敏效应

针对在低功率下工作的微波等离子体炬原子发射光谱法(MPT-AES)存在对一些元素检测灵敏度较低和抗基体干扰能力弱的问题,以氩气为载气和工作气,研究了表面活性剂及镧盐对MPT-AES测定铁的增敏效应,考察了铁测定的工作条件和共存元素对铁测定的影响.实验结果表明,非离子表面活性剂对铁的测定有抑制作用,而阳离子表面活性剂和镧盐对铁的测定有增敏作用,其中镧盐增敏效果最好.以镧盐为增敏剂,不仅可提高MPT-AES测定铁的灵敏度,还可增加共存元素的允许量.当体系中镧浓度为0.500 mg/m L时,至少可使40倍的锌,30倍的钴,20倍的镍、锰,15倍的钙,10倍的镁、铜和钠不影响铁的测定.与不加镧时相比,铁的发射强度提高了2.4倍,检出限由原来的27.5×10~(-3)μg/m L下降为8.5×10~(-3)μg/m L.将本方法应用于原油样品中铁的测定,所得结果与火焰原子吸收光谱法测定结果一致.