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)%.

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%).

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.

ICP-MS法和GF-AAS法检测乳粉中铬元素的测量系统评价

铬元素是食品质量安全重点监测项目,GB 5009.123—2023《食品安全国家标准食品中铬的测定》中规定了食品中铬的2种常用检验方法:石墨炉原子吸收光谱(graphite furnace atomic absorption spectrometry,GF-AAS)法和电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)法。使用Minitab统计分析工具,运用控制图法、独立样件法、t检验法及方差分析法对上述2种常用检验方法测量系统的稳定性、偏倚、线性、重复性与再现性进行分析。结果表明:2种检测方法测量系统极差图和均值图均无异常点,组内误差处于统计受控状态,稳定性良好;量具线性和偏倚分析结果均不存在显著偏倚和显著线性误差;量具R&R报告分析结果表明,ICP-MS法和GF-AAS法测量系统重复性和再现性良好;双因子方差分析表明,样品是唯一显著影响测量误差的因子;研究变异分析表明,测量系统误差可以接受。ICP-MS法和GF-AAS法不仅能有效保障乳粉中铬元素含量检测数据的可靠性和可重复性,为实验室进行测量系统的误差分析与控制提供科学依据,同时也为乳制品中其他重金属检测及其他食品中重金属检测的测量系统评价提供一定参考。

GF-AAS与ICP-MS测定水中总铬含量的方法比对及其不确定度评定

石墨炉原子吸收光谱(GF-AAS)法和电感耦合等离子体质谱(ICP-MS)法是灵敏度较高的2种测定水中铬含量的方法。文中采用357.9 nm与429.0 nm波长条件下GF-AAS法、52与53质核比条件下ICP-MS法测定水质铬标准物质中总铬元素含量,从标准曲线、准确性、重复性、加标回收率、检出限、定量限、测量不确定度评定多个方面进行对比分析。结果表明,4组测定条件下,标准物质测定结果均在标准值不确定度范围内。其中,429.0 nm波长GF-AAS法测定结果相对其他3组显著偏低(P<0.05);ICP-MS法在检出限、定量限方面优于GF-AAS法;GF-AAS法测定结果357.9 nm波长优于429.0 nm波长。

Mechanism of boron atomization in graphite furnace atomic absorption spectroscopy

The mechanism of the atomization of boron and the enhancement of sensitivity by matrix modifier Sr(NO_3)_2 in graphite furnace AAS were discussed.X-ray diffraction and thermodynamic calculation were applied to study the mechanism of boron atomization with and without matrix mo- difier Sr(NO_3)_2.The formation of boron atom is due to the sublimation of solid boron which derived from the reduction of B_2O_3 by carbon.The enhancement of boron signal in the presence of Sr(NO_3)_2 is due to the formation of SrB_6 before atomization,which decreased the volatization losses of B_2O_3 and retarded the formation of B_4C.

土壤-苦丁茶树系统中铅的GF-AAS测定及其分布特性

采集不同苦丁茶树的根、茎、叶及对应的土壤样品,经过清洗、烘干、研磨等预处理后,采用高压密封罐加热消解,加入磷酸氢二铵作为基体改进剂,通过氘灯扣除背景,以石墨炉原子吸收光谱法(GF-AAS)测定样品中的铅,铅浓度在0.000—60.000ng.ml-1时与吸光度呈现良好的线性关系,相关系数r=0.9999,检出限为0.200ng.ml-1,方法精密度RSD<5%,回收率93%—107%.用上述方法研究土壤-苦丁茶树系统中铅的分布表明,各种苦丁茶树及土壤中铅的分布具有类似规律,即土壤中铅含量远高于茶树中,茶树的地下部分含量分布为:吸收根>主根,地上部分为:枯叶>茎>老叶>嫩叶,其中嫩叶中铅含量远低于限量指标(Pb≤5.0μg.g-1),对茶叶服用的安全性有利.

GF-AAS法测定处理污水灌溉土壤中铅最佳基体改进剂的选择及其应用

研究了石墨炉原子吸收法（GF-AAS法）测定一级处理污水灌溉土壤中铅最佳基体改进剂的选择及在最佳改进剂条件下测定污水灌溉土壤中铅的GF-AAS法。试验了磷酸二氢铵,磷酸铵,氯化铵,Pd-Mg和磷酸二氢铵＋硝酸镁＋硝酸铵等基体改进剂对测定一级处理污水灌溉土壤铅的基体改进作用,并根据基体改进剂的改进效果,最佳灰化温度和原子化温度,选定了最佳基体改进剂和测定条件。40 g·L^-1的磷酸二氢铵作为基体改进剂,灰化温度为850℃,原子化温度为1 600℃时,用氘灯校正背景GF-AAS法进行测定,测定方法的RSD为2.6%,回收率在92.4%-104%之内。

GF-AAS法测定庐山区农村饮用水中铅、镉的含量

通过对庐山区农村饮用水进行抽样测定了重金属Pb、Cd的含量,分析重金属Pb、Cd的污染情况。选取有代表性的水样28份,采用石墨炉原子吸收光谱法(GF-AAS)测定饮用其中Pb、Cd的含量。结果表明:28份水样中所含Pb量为(0.2386±0.4124)μg/L,Cd量为(0.0984±0.1456)μg/L。根据《生活饮用水卫生标准》(GB/T5750-2006),Pb限度为10μg/L,Cd限度为5μg/L,28份样本所测的重金属均在其限度范围内,表明庐山区农村饮用水没有重金属Pb、Cd的污染。

微波消解-GF-AAS测定荸荠及荸荠皮中的铅和镉

采用微波消解样品,石墨炉原子吸收光谱法测定荸荠及荸荠皮中铅和镉的含量。选定最佳的样品处理方法,并优化微波消解条件和仪器测定条件,对各种最佳分析条件进行了探讨和验证。研究表明,铅、镉的检出限分别为0.171、0.026μg/L;线性范围分别为0~60μg/L、0~4.0μg/L;加标回收率分别为94.0%~101.0%、92.0%~106.0%;RSD分别为4.2%、3.7%。用标准物质进行对照,其测定值均在给定的标准值范围内。

SS-GF-AAS法测定冬虫夏草中的铜元素

目的研究冬虫夏草中铜的含量。方法利用石墨炉原子吸收法,采取固体直接进样(solid sampling-graphite furnace-atomic absorption spectrometry,SS-GF-AAS)对冬虫夏草发酵菌丝体粉中的铜元素进行分析测定。结果 SS-GF-AAS实验结果显示,冬虫夏草发酵菌丝体粉中的铜元素含量在6.45～7.24mg/kg之间,平行样品的重复性相对偏差(RSD)为0.63%～5.37%,样品的日间重现性RSD为4.43%,此方法的回收率范围为91.19%～110.62%。结论该方法重现性良好,其测定结果的精密度及重现性可以同常用的液体原子吸收分光光度法相媲美。

GF-AAS法测定黄精中铬含量的方法研究

本文采用微波消解法对黄精样品进行前处理,利用石墨炉-原子吸收法(Graphite Furnace Atomic Absorption Spectrometry,GF-AAS)测定黄精中铬的含量。结果表明,当铬含量在0~10.0μg·L^(-1)线性关系较好,线性方程相关系数为0.9990,检出限为0.009 mg·kg^(-1),定量限为0.028 mg·kg^(-1),精密度、重复性试验(n=6)的RSD值≤2.50%,加标回收率(n=6)为96.2%~102.4%(RSD=2.49%)。该方法检出限低、易操作、结果准确,可用于黄精中重金属铬含量的测定。