Determination of vanadium in food and traditional Chinese medicine by graphite furnace atomic absorption spectroscopy

Various experimental conditions were described for the vanadium determinationby graphite furnace atomic absorption spectroscopy (GFAAS). The experiments showed that whenatomization took place under the conditions where the combination of a pyrolytic coating graphitetube and fast raising temperature were used and the temperature was stable, the signal peak shapescould be improved, the sensitivity was enhanced, and the memory effect was removed. The vanadium infood and traditional Chinese medicinal herbs can be accurately determined using the standard curvemethod.

Determination of Trace Amounts of Nickel (Ⅱ) by Graphite Furnace Atomic Absorption Spectrometry Coupled with Cloud Point Extraction

A new method based on the cloud point extraction（CPE） for separation and preconcentration of nickel（Ⅱ） and its subsequent determination by graphite furnace atomic absorption spectrometry（GFAAS） was proposed, 8-hydroxyquinoline and Triton X-100 were used as the ligand and surfactant respectively. Nickel（Ⅱ） can form a hy-drophobic complex with 8-hydroxyquinoline, the complex can be extracted into the small volume surfactant rich phase at the cloud point temperature（CPT） for GFAAS determination. The factors affecting the cloud point extraction, such as pH, ligand concentration, surfactant concentration, and the incubation time were optimized. Under the optimal conditions, a detection limit of 12 ng/L and a relative standard deviation（RSD） of 2.9% were obtained for Ni（Ⅱ） determination. The enrichment factor was found to be 25. The proposed method was successfully applied to the determination of nickel（Ⅱ） in certified reference material and different types of water samples and the recovery was in a range of 95%―103%.

Preconcentration of Vanadium(Ⅴ) on Crosslinked Chitosan and Determination by Graphite Furnace Atomic Absorption Spectrometry

A new method is proposed for the preconcentration of vanadium(Ⅴ) with crosslinked chitosan (CCTS) and determination by graphite furnace atomic absorption spectrometry (GFAAS). The adsorption rate of vanadium(Ⅴ) by CCTS was 97% at pH 4.0, and vanadium(Ⅴ) was eluted from crosslinked chitosan with 2 mL 2.0 mol·L -1 chlorhydric acid and determined by GFAAS. The detection limit (3σ,n=7) for vanadium(Ⅴ) was 4.8×1 0 -12g and the relative standard deviation (R.S.D) at concentration level of 2.6 μg·L -1 is less than 3.6%. The method shows a good selectivity and high sensitivity, and it was applied to determination of vanadium(Ⅴ) in oyster and water samples. The analytic recoveries are (97±5)%.

A Study of the Background Absorption of Chitosan in the Graphite Furnace Atomic Absorption Spectrometry

ＡＳｔｕｄｙｏｆｔｈｅＢａｃｋｇｒｏｕｎｄＡｂｓｏｒｐｔｉｏｎｏｆＣｈｉｔｏｓａｎｉｎｔｈｅＧｒａｐｈｉｔｅＦｕｒｎａｃｅＡｔｏｍｉｃＡｂｓｏｒｐｔｉｏｎＳｐｅｃｔｒｏｍｅｔｒｙＴＡＮＧＹｏｕ－ｗｅｎ＊ａｎｄＭＯＳｈｅｎｇ－ｊｕｎ（Ｄｅｐａｒｔｍｅｎ...

Determination of Trace Iron in High Purity Sodium Fluoride by Graphite Furnace Atomic Absorption Spectrometry

A method is described for the direct determination of iron in high purity sodium fluoride using graphite furnace atomic absorption spectrometry. Interferences caused by the matrix are investigated. It is shown that the ashing temperature can be increased to 1 400°C and matrix interferences eliminated, the sensitivity of iron increased in 1. 27 fold by the addition of nickel nitrate. The method is applied to the determination of iron in sodium fluoride and satisfactory results are obtained.

Determination of Trace Amounts of Lead by Modified Graphite Furnace Atomic Absorption Spectrometry after Liquid Phase Microextraction with Pyrimidine-2-thiol

The liquid phase microextraction (LPME) was combined with the modified Graphite furnace atomic absorption spectrometry (GF-AAS) for determination of lead in the water and solid samples. In a preconcentration step, lead was extracted from a 2 ml of its aqueous sample in the pH = 5 as lead-Pyrimidine-2-thiol cationic complex into a 4 μl drop of 1,2 dichloroethane and ammonium tetraphenylborate as counter ion immersed in the solution. In the drop, the lead-Pyrimidine-2-thiol ammonium tetraphenylborate ion associated complex was formed. After extraction, the microdrop was retracted and directly transferred into a graphite tube modified by [W.Pd.Mg] (c). Some effective parameters on extraction and complex formation, such as type and volume of organic solvent, pH, concentration of chelating agent and counter ion, extraction time, stirring rate and effect of salt were optimized. Under the optimum conditions, the enrichment factor and recovery were 525% and 94%, respectively. The calibration graph was linear in the range of 0.01 - 12 μg?L–1 with correlation coefficient of 0.9975 under the optimum conditions of the recommended procedure. The detection limit based on the 3Sb criterion was 0.0072 μg?L–1 and relative standard deviation (RSD) for ten replicate measurement of 0.1 μg?L–1 and 0.4 μg?L–1 lead was 4.5% and 3.8% respectively. The characteristic concentration was 0.0065 μg?L–1 equivalent to a characteristic mass of 26 fg. The results for determination of lead in reference materials, spiked tap water and seawater demonstrated the accuracy, recovery and applicability of the presented method.

A Study of the Background Absorption of Slurry Algae in the Graphite Furnace Atomic Absorption Spectrometry

In general, biological organisms have the ability to absorb a specific element selectively. Holcombe and his co-workers reported that copper, nickel and cobalt could be separated from riverine and sea-water samples and cadmium from river water samples by unicellular green algae and were determined by slurry GFAAS. Dar-

Determination of Pb Content in Soil Samples by Graphite Furnace Atomic Absorption Spectrometry

[ Objective] A method was established to determine trace Pb in soil by graphite furnace atomic absorption spectrometry. [ Method] The pre-treatment of soil sample was conducted by nitric acid -perchloric acid -hydrochloric acid system. Palladium nitrate was added to eliminate ma- trix interference. Digestion acid, ashing and atomization temperature of the sample were selected. The operating parameters of instrument and tem- perature-rise program of graphite furnace were optimized. National standard matter was used to verify accuracy of the method. [Result] The detec- tion limit for Pb was 0.27 μg/g by graphite furnace atomic absorption spectrometry, and the recovery rate was 91.0% -96.1%. [ Conclusion The method had rapid analysis velocity, high sensitivity, less interference and easy operation. When applied to determination of trace Pb in the soil, the method obtained satisfactory results.

Measuring Conditions for the Determination of Lead in Iron-Matrix Samples Using Graphite Atomizers with/without a Platform in Graphite Furnace Atomic Absorption Spectrometry

In graphite furnace atomic absorption spectrometry (GF-AAS), the atomization process of lead occurring in graphite atomizers with/without a platform plate was investigated when palladium was added to an iron-matrix sample solution containing trace amounts of lead. Absorption profiles of a lead line were meas- ured at various compositions of iron and palladium. Variations in the gas temperature were also estimated with the progress of atomization, by using a two-line method under the assumption of a Boltzmann distribu- tion. Each addition of iron and palladium increased the lead absorbance in both the atomizers, indicating that iron or palladium became an effective matrix modifier for the determination of lead. Especially, palladium played a significant role for controlling chemical species of lead at the charring stage in the platform-type atomizer, to change several chemical species to a single species and eventually to yield a dominant peak of the lead absorbance at the atomizing stage. Furthermore, the addition of palladium delayed the peak after the gas atmosphere in the atomizer was heated to a higher temperature. These phenomena would be because the temperature of the platform at the charring stage was elevated more slowly compared to that of the furnace wall, and also because a thermally-stable compound, such as a palladium-lead solid solution, was produced by their metallurgical reaction during heating of the charring stage. A platform-type atomizer with palladium as the matrix modifier is recommended for the determination of lead in GF-AAS. The optimum condition for this was obtained in a coexistence of 1.0 × 10–2 g/dm3 palladium, when the charring at 973 K and then the atomizing at 3073 K were conducted.

Investigation of Distribution for Trace Lead and Cadmium in Chinese Herbal Medicines and Their Decoctions by Graphite Furnace Atomic Absorption Spectrometry

Lead and cadmium in herbal medicines are highly toxic to living organisms even in low concentrations. An effective method is developed for analysis of trace lead and cadmium in Chinese herbal medicines and their decoctions by graphite furnace atomic absorption spectrometry (GFAAS). The effects of analytical conditions on absorbance were investigated and optimized. A water-dissolving capability for Pb and Cd was investigated, and the contents of different species in five Chinese herbal medicines and their decoctions were analyzed. The content ratios (kow) of n-octanol-soluble Pb or Cd to water-soluble Pb or Cd were evaluated, and the distribution of Pb and Cd in water decoction at stomach and intestine acidities was developed, in the first time. The contents of water-soluble Pb and Cd, n-octanol-soluble Pb and Cd, and their content ratios were related with the kind of medicine and the acidity of the decoction. The proposed method has the advantages of simple operation, high sensitivity and high speed, with 3 σ detection limits of 4.2 pg for Pb and 0.1 pg for Cd.

Determination of Heavy Metals at Sub-ppb Levels in Water by Graphite Furnace Atomic Absorption Spectrometry Using a Direct Introduction Technique after Preconcentration with an Iminodiacetate Extraction Disk

A direct analysis method combining an iminodiacetate extraction disk (IED) with graphite furnace atomic absorption spectrometry was developed for the determination of Co, Ni, Cu, Cd, Sn, Pb, and Bi at sub-ppb levels in water. A 100 mL water sample was adjusted to pH 5.6 with nitric acid and a 1 mol?L–1 ammonium acetate solution, and then passed through an IED (diameter, 47 mm;effective filtering diameter, 35 mm) at a flow rate of 80 - 100 mL?min–1 to preconcentrate seven analytes. The IED was dried at 100?C for 20 min in an electric oven, and 110 - 145 small disks, each 2 mm in diameter, were punched out from the IED. A small disk was introduced into the graphite furnace and atomized according to a heating program. For Cd, Sn, Pb, and Bi measurements, Pd was used as a chemical modifier to enhance the absorbances. Calibration was performed using aqueous standard solutions. The detection limits, corresponding to three times the standard deviation (n = 5) of the blank values, were 0.092 μg·L–1 for Co, 0.12 μg·L–1 for Ni, 0.40 μg·L–1 for Cu, 0.077 μg·L–1 for Cd, 0.92 μg·L–1 for Sn, 0.61 μg·L–1 for Pb, and 0.80 μg·L–1 for Bi with an enrichment factor of 140 using a 100-mL water sample. A spike test for the seven analytes in tap water, rainwater, river water, and mineral drinking water showed quantitative recoveries (93% - 108%).

ICP-MS和GFAAS检测生活饮用水中镉、铬、铅的方法比较

目的:探索实验室检测生活饮用水中镉、铬、铅元素含量经济便捷的方法。方法:比较电感耦合等离子体质谱(Inductively Coupled Plasma Mass Spectrometry,ICP-MS)法和石墨炉原子吸收光谱(Graphite Furnace Atomic Absorption Spectrometry,GFAAS)法检测生活饮用水中镉、铬、铅元素含量的相关系数、方法检出限、回收率、重复性和精密度等。结果:两种方法在对应浓度范围内线性关系良好,r值均大于0.999;ICP-MS法的检出限为0.001 05~0.022 10μg·L^(-1),GFAAS法的检出限为0.067 1~1.120 0μg·L^(-1);ICP-MS法的回收率为96.5%~105.4%,GFAAS法的回收率为93.4%~100.6%;ICP-MS法的精密度为0.596%~0.922%,GFAAS法的精密度为2.52%~3.99%;两种方法的相对标准偏差均小于5%。结论:两种方法均具有检出限低、灵敏度高、分析精密度高的特点,实验室可根据需测元素、成本及效率等情况,选择合适的方法。

电感耦合等离子体质谱法(ICP-MS)和石墨炉原子吸收光谱(GFAAS)法测定大米粉中铅含量的探讨和比较

采用微波消解前处理方法,建立电感耦合等离子体质谱法(ICP-MS)和石墨炉原子吸收光谱法(GFAAS)测定大米粉中铅含量的方法,并进行比较分析。结果表明ICP-MS法和GFAAS法均能对大米粉中的铅元素进行很好的分析测定,校正曲线的相关系数均在0.999以上,线性关系良好;各方法铅元素检出限均小于国标方法要求的检出限,灵敏度较高;加标回收率范围在93.9%~103.2%之间,回收率良好;相对标准偏差RSD值均小于5.0%,精密度良好;大米粉标准物质测定值均在标示值范围内,准确度良好。

悬滴微萃取-高分辨连续光源石墨炉原子吸收光谱法测定高纯石墨中的超痕量金

准确测定高纯石墨中的超痕量金,难点是如何在最大程度地减少样品前处理过程中器皿、试剂、材料、环境及设备所引入的二次污染的前提下,实现对样品溶液中超痕量金(0.1~1ng/mL)的有效分离和高倍富集。本文建立了铂皿中灰化、酸解、磷酸三丁酯悬滴微萃取的方法用于高纯石墨中超痕量金分析。首先于铂皿中高温灼烧除去样品中的固定碳,然后采用氢氟酸-王水-高氯酸将灰分消解完全制备成样品溶液,再以微升级磷酸三丁酯悬滴作为萃取剂,分离富集样品溶液中的金,最后采用高分辨连续光源石墨炉原子吸收光谱法(GFAAS)对悬滴中的金进行测定。实验结果表明,使用2.5μL磷酸三丁酯悬滴(氯仿体积为20%)作为萃取剂,在10%盐酸介质的样品溶液中萃取金2min,对金的富集倍数可达283倍。在实验条件下,金的质量浓度在0.1~2.0ng/mL范围内与其吸光度呈良好的线性关系,相关系数r为0.999,检出限为0.11ng/g,样品溶液中一定量的共存元素(如钠、镁、铝)对金的测定无干扰。按照实验方法测定5个高纯石墨实际样品中的金含量,测定结果的相对标准偏差(RSD,n=6)为1.5%~4.9%,加标回收率为94.9%~105.3%。

石墨炉原子吸收光谱法测量干香菇镉含量的不确定度来源评定

依据国家计量技术规范《测量不确定评定与表示》(JJF 1059.1—2012),针对干香菇镉含量的原子吸收光谱法(石墨炉法)检测过程,分析测量不确定度的来源,不确定度主要来源于测量重复性、标准物质、样品制备、线性拟合标准曲线、石墨炉原子吸收光谱仪等5个方面,通过建立相应的数学模型,计算评定上述5个方面来源的相对标准不确定度分别为0.00743、0.00268、0.02275、0.00866和0.00005,合成标准不确定度为0.0151 mg∕kg,最终得出测量结果的扩展不确定度为0.03 mg∕kg。结果表明,在该试验中标准曲线线性拟合计算质量浓度是不确定度引入的最主要因素。

Cd在污泥厌氧消化中的检测及其对产沼气的抑制研究

为了研究重金属Cd对污泥厌氧消化产甲烷的影响,在序批式反应器中,通过控制进料中Cd的浓度,分析了Cd在污泥处理系统内的检出与去除规律,以及Cd对污泥厌氧消化产甲烷的影响。研究结果表明,石墨炉原子吸收光谱法能有效检测污泥中Cd的浓度,且Cd的初始浓度会影响Cd的去除效率;浓度>1.0 mg·L-1的Cd抑制了污泥厌氧消化产甲烷,最低甲烷产量为77.9 mL·g-1;Cd降低了污泥厌氧消化内有机质的水解,5.0 mg·L-1的Cd暴露组中溶解性COD和挥发性脂肪酸(VFA)的最大值分别为1455 mg·L-1和794 mg·L-1,低于对照组。高浓度Cd会降低污泥减量率,至24.5%,增加了污泥后续处理的难度。

苯基荧光酮沉淀捕集-GFAAS测定痕量镓、锗、钼和铟

以苯基荧光酮沉淀捕集溶液中的痕量镓、锗、钼和铟,用石墨炉原子吸收法进行测定。研究了溶液酸度、苯基荧光酮(PF)用量、陈化时间、溶液体积以及共存元素的影响。最佳条件分别为:Ga(Ⅲ):500 mLpH≈2溶液中加入10.00 mg.mL-1PF 2.00 mL,陈化4h;Ge(Ⅳ):500 mL pH≈2溶液中加入10.00 mg.mL-1PF 4.00 mL,陈化10 h;Mo(Ⅴ):1 000 mL pH≈3溶液中加入10.00 mg.mL-1PF 3.00 mL,陈化6 h;In(Ⅲ):100 mL pH≈5溶液中加入10.00 mg.mL-1PF 4.00 mL,陈化10 h。实验显示,苯基荧光酮沉淀对痕量镓、锗、钼和铟的捕集过程以后沉淀为主。方法检出限(3s):镓0.12 ng.mL-1,锗0.30 ng.mL-1,钼0.046 ng.mL-1,铟2.7 ng.mL-1。该方法成功地用于石墨炉原子吸收测定水溶液、国家地质标准物质和锌精矿中痕量镓、锗、钼和铟。

不完全消化-微乳液进样-HR-CS GFAAS测定休闲食品中5种金属元素

建立不完全消化-微乳液进样-高分辨-连续光源石墨炉原子吸收光谱法测定休闲食品中Cu、Al、Cr、Cd和Pb的方法。以不完全消化作为样品的前处理方式,正丁醇作为助乳化剂,研究微乳液的形成条件,系统地分析基体改进剂及其添加体积、灰化温度和原子化温度对吸光度和吸收峰峰形的影响,通过单因素试验确定Cu、Al、Cr、Cd和Pb的最佳测定条件。将本法所测得的结果与微波消解作为前处理方式所测得的结果进行比较,两者相近,本法的加标回收率为96.4%~105.6%。该方法快速、准确、稳定,具有较高的实用价值,为休闲食品中多元素检测提供了科学依据。

以壳聚糖为母体的螯合树脂预富集GFAAS测定痕量金的研究

以壳聚糖为原料 ,经环氧氯丙烷适当交联 ,与N ,N 二乙基胺基环氧丙烷作用 ,合成了凝胶树脂。实验证明 ,该树脂在强酸介质中不溶解 ,对Au 具有较强吸附作用 ;经超声波富集后 ,用GFAAS法测定 ,富集效率达到 98%以上 ,将该法用于测定矿样中微量金 ,效果好。

交联羧甲基魔芋葡甘聚糖微柱预富集-GFAAS测定痕量铅、镉、铜的研究

建立了用交联羧甲基魔芋葡甘聚糖(CCMKGM)作为微柱预富集填料,分离富集-GFAAS测定环境水样中痕量铅、镉和铜的新方法。研究了溶液酸度、样品的流速和体积、洗脱剂的浓度和体积、共存离子等对CCMKGM微柱吸附重金属离子的影响。结果表明:在pH为5.0～7.0的条件下,三种重金属离子可定量吸附在CCMKGM微柱上;采用1.0mL0.5mol.L-1的盐酸溶液可将吸附在CCMKGM微柱上的铅、镉和铜定量洗脱。Pb2+,Cd2+,Cu2+的检出限(3σ)分别为0.038,0.0005和0.014μg.L-1,相对标准偏差(RSD)分别为3.5%,9.2%和4.7%(初始浓度cPb2+=cCu2+=1.0μg.L-1,cCd2+=0.1μg.L-1,n=11),富集倍数50。将该法用于环境标准样品的测定,测得值与标准值相符。