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%.

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

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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)%.

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%).

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。

双水相萃取-连续光源石墨炉原子吸收光谱法测定水样中的痕量锑

提出了以吡咯烷基二硫代氨基甲酸铵(APDC)为螯合剂,乙腈为萃取剂,氯化钠为无机盐的双水相萃取-连续光源石墨炉原子吸收光谱法测定水样中痕量锑的方法。优化的双水相萃取Sb^(3+)的条件如下:螯合反应体系酸度为pH 4,0.5 mL的2 g·L^(-1)APDC储备溶液,1.6 mL的乙腈,1.2 g的氯化钠,反应时间为20 min。在此试验条件下,Sb^(3+)的质量浓度在1.00~20.00μg·L^(-1)内与对应的吸光度呈线性关系,检出限(3 s/k)为0.048μg·L^(-1)。分别对5.00,10.00μg·L^(-1)的Sb^(3+)标准溶液测定10次,测定值的相对标准偏差为4.6%和3.3%。按照标准加入法对实际样品进行回收试验,回收率为95.8%~102%。将此方法用于检测自来水、河水、湖水中的痕量锑,显示这些环境样品中含有部分痕量锑。

永泰县话梅中铅含量的检测分析

为调查研究永泰县话梅中铅含量情况,采购永泰县当地产话梅200份,采用石墨炉原子吸收光谱法对其铅含量进行检测分析。结果表明,永泰县话梅中铅的含量为0~1.10 mg·kg^(-1),平均含量为0.31 mg·kg^(-1),仅有1份话梅样品中铅含量超过0.8 mg·kg^(-1)的国家限量标准。200份话梅样本中铅检出率为85%,铅含量为0.41~0.80 mg·kg^(-1)的占17%,0.4 mg·kg^(-1)以下的占82.5%,整体合格率为99.5%,说明目前永泰县话梅质量安全较高,生产卫生较好。

Tamm溶液提取-石墨炉原子吸收光谱法测定土壤中有效钼

提出了Tamm溶液提取-石墨炉原子吸收光谱法对土壤样品中有效钼的测定方法。有效钼标准曲线的相关系数为0.9995,方法检出限为0.005 mg/kg,定量限为0.018 mg/kg;采用有证标准物质对方法适用性进行了考察,本方法测定值与认定值基本一致,且相对误差(RE)不大于4.17%,相对标准偏差(RSD)不大于7.87%,本方法检出限低、精密度和正确度较好,满足土壤样品测试工作的要求,简化了工作流程,提高了工作效率,适用于批量土壤样品中有效钼的测定。

石墨炉原子吸收法测定一回路冷却剂中锌的方法研究

压水堆核电厂采用一回路加锌技术能够有效降低电站的堆芯外辐射场,降低人员辐照剂量。采用加锌技术的核电厂需要监测一回路冷却剂中的锌含量,通常采用电感耦合等离子体发射光谱法或石墨炉原子吸收光谱法进行测定。石墨炉原子吸收光谱法检测限低、准确度高,但高浓度的硼酸基体严重干扰测定。本文为国内首次研究采用乙醇作为基体改进剂,在石墨炉升温过程中去除硼酸,消除干扰。经验证,方法有效,从根本上解决了使用石墨炉原子吸收光谱法测定一回路冷却剂锌含量时存在的问题。

石墨消解-石墨炉原子吸收光谱法测定土壤中锑和铋

建立石墨炉原子吸收光谱法测定土壤中锑和铋残留的方法。采用自动石墨消解仪对土壤样品进行消解,并对基体改进剂、原子化温度等实验条件进行优化。锑、铋在0.00~40.0μg·L^(-1)浓度范围内线性良好,方法检出限分别为0.006μg·g^(-1)和0.004μg·g^(-1),实际样品加标回收率分别为91.7%和98.3%。本方法操作简便,测试结果准确度、精密度和加标回收率均满足质量控制要求,适用于大批量土壤中锑、铋含量的测定。

快速消解-石墨炉原子吸收法测定鸡蛋中铅、镉、铬、铜含量

建立快速消解-石墨炉原子吸收法测定鸡蛋样品中铅、镉、铬、铜的含量。优化了快速消解-石墨炉原子吸收光谱法测定条件,在最佳实验条件下,采用纯硝酸消解鸡蛋样品,选用磷酸二氢铵为基体改进剂。铅、镉、铬、铜的质量浓度在各自的范围内与吸光度呈良好的线性关系,相关系数均大于0.999,各元素的检出限为0.006~0.066μg/g。样品加标回收率为94.6%~108.3%,测定结果的相对标准偏差小于10%(n=6)。该方法操作简便,准确度高,精密度好,可用于大批量鸡蛋样品检测铅、镉、铬、铜含量。

石墨炉原子吸收光谱直接法测定镍基高温合金中镉含量

采用硝酸、氢氟酸溶解镍基高温合金试样,建立石墨炉原子吸收光谱法测定镍基高温合金中镉元素含量。采用灰化温度500℃,原子化温度1200℃,对镍基高温合金试样进行测定。镉元素质量分数在0.1~20.0μg/g范围内与其吸光度线性关系良好,相关系数均大于0.99。通过标准物质对照和加标回收试验验证方法准确度,方法检出限和定量限分别为0.0029、0.01μg/g,样品加标回收率为91.8%~107.8%,相对标准偏差小于4.5%(n=11)。该方法灵敏度高,准确性好,适用于镍基高温合金中镉元素的质量控制。

石墨炉原子吸收分光光度法测定水中铟不确定度分析

铟作为一种环境污染物,其化合物具有致癌作用和生物毒性,是水质监测的一项重要的指标。为了确定检测过程中不确定度的主要来源,如实反映测量数据的置信度和准确度,提高检测质量,对石墨炉原子吸收分光光度法测定水中铟不确定度进行分析和评估。参照不确定度的评定规范和石墨炉原子吸收分光光度法对水中铟的测定原理建立数学模型,分析了包括重复性、标准储备液、标准曲线配制、标准曲线拟合、测量仪器以及样品前处理等不确定度来源,分别计算了各不确定度分量、合成标准不确定度和扩展不确定度。结果表明水中铟的平均值为19μg/L,扩展不确定度为5.6%,水中铟含量结果表示为19±2μg/L,k=2。经过评估分析,测定水中铟的不确定度的主要影响因素为样品的重复性处理和标准溶液的配制。