Cadmium analysis in soil by microwave acid digestion and graphite furnace atomic absorption spectrometry

The need to determine micronutrients and toxic elements in soils has grown in recent years and cadmium is of special interest. A method has been developed for the determination of cadmium in soils based on a prior acid digestion of the samples with nitric acid in closed Teflon vessels, into a microwave over. The cadmium determination was carried out by graphite furnace atomic absorption spectrometry (GFAAS) with Lvov platform. Optimum operating conditions, analyte modifiers and matrix interferences have been investigated. The best matrix modifier was found to be ammonium dihydrogen phosphate. The interferences are greatly reduced under these operating conditions and calibration can be performed with simple aqueous solutions of the metal standard. The method is rapid and provides accurate and precise results that agree with certified values for two reference materials: BCR 141 (calcareous loam soil) and BCR 277 (estuarine sediment).     

Determination of cadmium in orthophosphoric acid by graphite furnace atomic absorption spectrometry

Summary Cadmium has been determined in analytical-reagent grade orthophosphoric acids by direct graphite furnace atomic absorption spectrometry with Zeeman background correction. The detection limit was 3.0 pg cadmium, corresponding to 1.0 g/l of cadmium in the concentrated acid. Most of the acids analyzed contained 2–5 g/l of cadmium. The method was checked using electrochemical preconcentration of cadmium, followed by flame atomic absorption spectrometry.     

微波消解-GFAAS测定浅水湖泊底泥中重金属元素

探讨了采用微波消解作为底泥样品的前处理方法,运用石墨炉原子吸收法测定浅水湖泊底泥中Cu,Pb,Zn,Cd,Cr含量的实验条件.方法的RSD为2.0％～4.1％,平均回收率为97.4％～101.5％,Cu,Pb,Zn,Cd,Cr的检出限分别为0.4,5,2.8,0.25,2.5ng.该法适合于浅水湖泊底泥中重金属含量的测定.     

Trace metal analyses in octocorals by microwave acid digestion and graphite furnace atomic-absorption spectrometry

Eight octocoral species from two reefs off the Venezuelan coast were analyzed to determine their Cd, Cu, Ni, Pb and Zn content. A microwave sample work-up procedure, including drying and acid digestion, was developed and found to be faster and more convenient than conventional methods. Accurate and precise results were obtained for the determination of the metals of interest, using graphite furnace atomic-absorption spectrometry (GFAAS) with L'vov platforms. The accuracy of the results was checked against synthetic standards prepared to simulate the matrix of the analyzed octocoral species. Standard deviation values for synthetically prepared standards were less than 1% in all cases. On the other hand, standard deviations for sample results were considerably higher due to heterogeneity of the samples and environmental conditions at the sampling sites.     

微波消化-石墨炉原子吸收法测定食用油脂中的铜

用微波消化技术对各种食用油脂试样进行预处理，针对样品特性，优化较佳的微波消化条件与操作参数，建立了用微波消化－石墨炉原子吸收法测定食用油脂中的铜，减少了样品处理过程中的损失，回收率为92.4%-96.2%；RSD为3.0%-3.6%, 检出限为0.05mg/kg。     

Slurry sampling for graphite furnace atomic absorption spectrometry

Summary Slurry preparations are an effective way to introduce solids into the graphite furnace. Ultrasonic agitation keeps samples mixed prior to analysis. Several aspects of the ultrasonic slurry sampling approach are discussed including contamination concerns, analyte partitioning, and the effect of particle size. In addition, sample preparation strategies for slurry preparations of non-powdered materials are reviewed. The suitability of this method for assessing homogeneity is demonstrated.     

Latest innovations in graphite furnace atomic absorption spectrometry technique

An overview of the latest innovations in the graphite furnace atomic absorption spectrometry technique is described. The use of the transverse heated graphite atomizer technology with its huge advantages, the possibilities of running powdered solids through the slurry technique, and the future possibility of using flow injection on-line with the graphite furnace are mentioned.     

Advances in ultrasonic slurry graphite furnace atomic absorption spectrometry

Summary Ultrasonic slurry graphite furnace atomic absorption spectrometry is a useful technique for automated direct analysis of solids. The effectiveness of ultrasonic agitation for mixing samples is demonstrated. This analytical approach is evaluated to identify sources of imprecision. Strategies for optimizing slurry preparations are discussed, focusing on particle size, density, analyte partitioning, and sampling limitations. Finally, a teflon bead method is presented for grinding biological and botanical samples. An optimized general approach for ultrasonic slurry sampling is presented.Presented at the 5th International Colloquium on Solid Sampling with Atomic Spectroscopy, May 18–20, 1992; Geel, Belgium. Papers edited by R. F. M. Herber, Amsterdam.     

Mechanism of modification by palladium in graphite furnace atomic absorption spectrometry

The effects of palladium and mixtures containing palladium on the absorbance characteristics of lead, thallium, cadmium, selenium, manganese and cobalt are described. These data, together with results of scanning electron microscopy showing the distribution of palladium on the graphite surface, indicate that palladium has a physical mechanism of analyte modification. During furnace heating, the analyte dissolves in molten palladium and may combine with it chemically. However, the rate limiting step leading to atomization appears to be diffusion of the analyte from palladium. The addition of magnesium, molybdenum or powdered carbon increases the speed of diffusion by causing palladium to form smaller droplets, and hence produces sharper absorbance peaks. Palladium becomes less effective as the atomization temperature increases, because the rate of diffusion is higher. This accounts for palladium having only a small stabilizing effect on less volatile elements such as manganese and cobalt. The addition of ascorbic acid to palladium has no significant effect on its modifying properties in a dilute nitric acid matrix. Results of kinetic studies on the atomization of gold are consistent with analyte diffusion out of palladium as the rate-limiting step leading to atomization.     

石墨炉原子吸收光谱法测定茶叶中的铅

采用石墨炉原子吸收光谱法测定茶叶中铅,以NH4H2PO4作为基体改进剂,提高了测定的灰化温度,消除了基体干扰.方法简便,快速,准确度高.通过对标准物质的多次测定,结果均在其保证值范围内,相对标准偏差为2.8%.对样品进行加标回收试验,回收率为96%～105%,方法检出限为0.12μg/L.     

On the direct analysis of solid samples by graphite furnace atomic absorption spectrometry

Summary We have studied some limitations of the solid sampling, cup-in-tube technique by comparison with a constant temperature two-step atomiser and found consistently lower vapour-phase temperatures and greater interferences in the former. With the former, higher vapour-phase temperatures and improved analytical results for lead and cadmium were found using Pd(NO₃)₂+Mg(NO₃)₂ instead of NH₄H₂PO₄+Mg(NO₃)₂ as modifier. Investigations of methods to extend the useful calibration range revealed reduced vapour-phase temperatures in the presence of a convective gas flow during atomisation, and a greater potential for errors using non-resonance lines. With respect to the latter, the absorbance signal is much more sensitive to matrix induced changes in the temperature interval in which atoms are formed compared to resonance lines. Furthermore, at the lead 261.4 nm non-resonance line we observed overcompensation errors caused by cobalt when using a Zeeman-effect system, and undercorrection due to the AlCl(g) molecule with a continuum source background corrector.     

石墨炉原子吸收测定模拟体液中的镍

人工关节置换手术的出现是外科手术治疗软骨病损的一次巨大的进步。但人工关节假体的后期松动是长期困扰其发展的难题。镍钛合金人工关节假体材料在体液中的腐蚀与磨损,以及磨损颗粒引起周围组织的异物反应,是造成晚期关节假体松动的主要原因。另一方面,镍钛合金植人体在体液腐蚀下释放的镍离子对人体有害,而且还可能致癌。因此,对镍钛合金进行表面改性,以提高其耐磨与耐腐蚀性能很有必要。     

Quantitative element analysis by isotope dilution in diode laser graphite furnace atomic absorption spectrometry

The paper reviews the application of the isotope dilution technique in optical atomic absorption spectrometry by use of a low-pressure graphite tube furnace as atomizer and diode lasers as radiation sources. The principles and the methodology to obtain accurate quantitative results despite of the occurrence of interferences are presented. The successful application of different Doppler-limited and Doppler-free spectrometric techniques is also presented. The perspectives but also the limitations of this new method are discussed.     

石墨炉原子吸收法测定石脑油中微量砷

试样用四氢呋喃（THF）有机溶剂稀释,以硝酸镍为基体改进剂,研究采用石墨炉原子吸收法直接进样测定石脑油中的砷量。研究表明,砷量在0～50μg／L范围内线性关系良好,回收率93％～104％。     

石墨炉原子吸收光谱法测定食盐中钡

建立了石墨炉原子吸收光谱法测定食盐中钡的方法,不需要对石墨管做任何处理,也无需对样品进行除盐处理,通过优化石墨炉升温程序,极大改善了食盐样品中钡测定的灵敏度和峰型。钡在0.00~50.0 μg/L浓度范围呈现良好的线性关系,相关系数优于0.999,检出限为0.650 mg/kg(以称样量0.200 g,定容至50 mL计算)。食盐样品钡加标回收率范围为81.3%~105.1%,相对标准偏差在8.9%以内。方法稳定可靠,准确度较高,适用于食盐中钡的测定。     

Pigment identification in artwork using graphite furnace atomic absorption spectrometry

The use of a sampling technique is described for the identification of metals from inorganic pigments in paint. The sampling technique involves gently contacting a cotton swab with the painted surface to physically remove a minute quantity (∼1-2 μg) of pigment. The amount of material removed from the painted surface is invisible to the unaided eye and does not cause any visible effect to the painted surface. The cotton swab was then placed in a 1.5 ml polystyrene beaker containing HNO₃ to extract pigment metals prior to analysis using graphite furnace atomic absorption spectrometry (GFAAS). GFAAS is well suited for identifying pigment metals since it requires small samples and many pigments consist of main group elements (e.g. Al) as well as transition metals (e.g. Zn, Fe and Cd). Using Cd (cadmium red) as the test element, the reproducibility of sampling a paint surface with the cotton swab was approximately 13% in either a water or oil medium. To test the feasibility of cotton sampling for pigment identification, samples were obtained from paintings (watercolour and oil) of a local collection. Raman spectra provided complementary information to the GFAAS, which together are essential for positive identification of some pigments. For example, GFAAS indicated the presence of Cu, but the Raman spectra positively identified the modern copper pigment phthalocyanine green (Cu(C₃₂Cl₁₆N₈). Both Raman spectroscopy and GFAAS were useful for identifying ZnO as a white pigment.     

石墨炉原子吸收法测定3-苯基丙烯酸酯类化合物中微量钯

利用高灵敏的石墨炉原子吸收法,在V(HCl):V(HNO3):V(H2O)＝5:1:94混合酸介质中测定苯基丙烯酸酯类化合物中的钯量.已纯化样品钯量的平均值是6.76 μg/g,标准相对偏差是4.8%,平均回收率为99.3%;未纯化样品钯量的平均值是121.2 μg/g,平均相对偏差是5.4%.还讨论酸介质对测定钯吸光度的影响,通过比较找到了合适的酸介质组成.     

Low volume microwave digestion for the determination of selenium in marine biological tissues by graphite furnace atomic absorption spectroscopy

A microwave digestion method for the determination of marine biological tissues has been developed to allow determination of selenium in small sample sizes (< 0.1 g). The benefits of this technique include maintaining concentrates in extracts without the subsequent over dilution encountered when using larger vessels, increased sample throughput and reduced loss of volatile material. Freeze dried biological material (< 0.1 g) and nitric acid (1 ml) were placed into 7 ml screw top Teflon vessels which are completely sealed on capping. Two 7 ml vials were placed into larger 120 ml vessels fitted with a Teflon spacer and 10 ml of distilled water. The effects of microwave power and time, and sample mass on selenium recovery from three marine standard reference materials (NIST SRM 1566a Oyster Tissue, NRCC DORM-1 Dogfish Muscle and NRCC TORT-1 Lobster Hepatopancreas) were examined. The optimum conditions: 600 W, 2 min; 0 W, 2 min; 450 W, 45 min, allowed quantitative recoveries of selenium from these and three other standard reference materials (NRCC DOLT-1 Dogfish liver, NIST RM-50 Albacore tuna and IAEA MA-A-2 fish flesh). Studies on sample mass showed that the analysis of sample masses from 0.025 to 0.1 g gave selenium concentrations within the certified range. Six species of selenium: selenite, selenate, selenomethionine, selenocysteine, selenocystamine, and trimethyl selenonium were added to oyster, dogfish, and lobster tissues. Recoveries were near quantitative for all species (94–105%) except trimethyl selenonium (90–101%).