A new furnace design for constant temperature electrothermal atomic absorption spectroscopy

A new concept is described for the production of atomic vapour with a constant temperature graphite furnace. Samples are manually or automatically dosed into a graphite cup which is fastened tightly to an aperture of a graphite tube. For atomization, the tube is heated to a preselected temperature followed by heating of the cup by means of a separate power supply. Experimental results are given to characterize the performance of the furnace with regard to sensitivity, non-specific absorption and interference effects. Possible applications of the system are discussed.     

The graphite probe constant temperature furnace

A graphite probe, on which the sample is deposited, is thrust into a heated graphite furnace tube, providing a constant temperature furnace environment. By comparison with wall sampling, the graphite probe system provides equal or improved sensitivity and detection limit and considerably less memory effect. Experiments with metals that range from volatile to refractory show that the peak width is the same at the same atomization temperature. A tube was designed that provided a curtain of argon to limit the absorbance path to about 15 mm.     

Analytical carbon furnace atomic emission: Temperature measurements and excitation mechanism

Atomic emission has been observed from 20 elements in an electrically heated graphite furnace. Two-line temperature measurements carried out on iron indicate an excitation temperature of ca. 2450 K when the temperature of the furnace walls is ca. 2420 K. Calibration curves have been obtained for Al, Mo and Cr, each showing a useful working range. The detection limit for Al was 5 pg, and for Cr and Mo was 140 pg. Bismuth was found to give a poor detection limit (10 ng). Time resolved traces of background emission and line emission intensity shows the validity of using the two-line method to measure the excitation temperature of iron. A thermal excitation mechanism of emission is proposed.     

Determination of cadmium in paint samples by graphite furnace atomic absorption spectrometry with optical temperature control

A graphite furnace atomic absorption spectrometry (GFAAS) method with optical temperature control for the determination of trace cadmium in paint samples is described. Optical temperature control was superior in many respects to current temperature control. The sensibility increased by 60%, the linear range widened by 60%, and the life of graphite tube showed a 200–300% increase because atomization temperature was lowered distinctly and atomization time was shortened. Use of lanthanum chloride as a matrix modifier was investigated. The linear range of calibration curve was 0–24 ng mL⁻¹. The detection limit was 9.6 ng L⁻¹. The characteristic mass was 3.0 pg. The method also resulted in excellent reproducibility (≤2.5% R.S.D.) at such low levels, and the recovery of added cadmium in paint samples was from 94.6% to 102%. This method is readily applicable to the determination of cadmium in paint samples.     

微波消解-GFAAS法测定菠菜粉和蘑菇粉中微量镉的研究

应用微波消解-石墨炉原子吸收光谱法对菠菜粉和蘑菇粉中微量镉的含量进行测定。菠菜粉和蘑菇粉经HNO3+H2O2微波消解体系消解后,采用磷酸二氢铵作为基体改进剂,灰化温度为900℃,原子化温度为1 350℃,镉含量在0~2 ng/mL范围内与吸光度呈线性关系,线性相关系数为0.999 4,检出限为0.02 mg/kg。该法测定结果的相对标准偏差小于4%(n=6),加标回收率为96.7%~103.2%。     

A triangular wave form generator

A simple generator for triangular waveforms is described. It uses two operational amplifiers to give triangular waves between 0 V and a preselected voltage. The scan rate and limit can be varied independently.     

The determination of oxygen in brass and zinc by a vacuum carbon-reduction techniques

A vacuum carbon-reduction technique for the determination of oxygen in brass and zinc has been studied. As a preliminary, zinc is removed from the samples, sealed in predegassed graphite capsules, in a silica furnace maintained at ca. 850°C under vacuum in a vacuum fusion instrument. The residual contents of the capsules are then analysed in sequence at 1450°C in the main furnace of the apparatus, to which they are transferred without breaking the vacuum. The procedure developed affords a detection limit of 0.5–1 ppm of oxygen for samples weighing ca. 1.5 g.     

探针-石墨炉原子吸收光谱法测定岩石矿物中的金

本文采用自制探针系统对探针-石墨炉原子吸收光谱法测金的性能,探针系统的制作,探针的处理,探针原子化法的检测限,灵敏度及抗干扰能力进行了详细的研究,探针原子化的各项指标均优于常规的管壁原子化法。采用本法可不必分离基体物质,直接测定地质样品中的金,所得结果与萃取原子吸收法的结果相吻合。     

Determination of inorganic tin and organotin compounds by graphite-furnace atomic absorption spectrometry with a new matrix modifier

The determination of total tin in water samples by graphite-furnace atomic absorption spectrometry is described. A matrix modifier containing 0.4% (w/v) potassium dichromate and 0.2% ammonium dihydrogenphosphate in 2% nitric acid is proposed. Interferences from major ions in natural fresh waters decreased and the sensitivity is greatly improved. The procedure is compatible with all the commercial injection devices and requires no pretreatment of the graphite furnace or use of a stabilized temperature platform. The 3σ detection limit is 0.62 ng Sn ml^?1, and calibration is linear up to 30 ng ml^?1 tin.     

石墨探针—原子吸收光谱法测定人发中痕量铟的研究

探针原子化技术是一种实现等温原子化,改善灵敏度的行之有效的方法。本文采用此方法对痕量钿进行了一系列条件试验,峰面积与钿浓度在0～50ng·ml~(-1)范围内呈线性关系,其特征量4.8pg,检出限21.5pg,相对标准偏差5.7％,并成功地测定了成人发中铟的含量,范围在12～159pg·g~(-1),回收率96.4％～103.2％。该方法灵敏度高,操作简单、快速,结果满意。     

Direct Determination of Total Chromium in Sea Water by Graphite Furnace Atomic Absorption Spectrometry with Multiple Injections

The method of multiple injections coupled with graphite furnace and atomic absorption spectrometry is applied to direct determination of total chromium at extremely small concentrations in samples of open sea water. The method involves the in situ preconcentration of trace chromium in sea water onto a pyrocoated graphite tube by multiple injections (up to 4 × 90 μL) prior to analysis. The selected ashing temperature is up to 1800 °C, and the background signal caused by high sea-salt contents will be markedly reduced when the ashing time is prolonged up to 200 s. A CASS-2 reference sea water has been used as a quality control sample in the analyses of samples of open sea water samples; the results were found to agree with the certified value. Due to the use of a relatively large volume (up to 0.36 mL) of sample for direct determination of trace chromium in sea water, the detection limit for chromium is 0.057 ppb.     

Determination of Lithium in Copper by Carbon Furnace Atomic Emission Spectrometry

Abstract

Carbon furnace atomic emission spectrometry has been used for the determination of lithium in copper. The method involves dissolution of the sample in nitric arid and direct injection into the carbon furnace. The detection limit for lithium is 0.00007 μg/ml Li in aqueous solution and 0.000014% Li in the copper samples.     

Determination of mercury in environmental samples by cold vapour generation and atomic-absorption spectrometry with a gold-coated graphite furnace

Mercury is determined at below the pg/ml level by a combination of cold vapour generation, trapping in a gold-coated graphite furnace and atomic-absorption detection. The mercury is reduced to the element by stannous chloride, stripped from solution by a stream of nitrogen and collected on a gold-coated porous graphite disk in a graphite furnace. It is then atomized by increasing the graphite furnace temperature and detected by an atomic-absorption spectrophotometer. The absolute detection limit and the characteristic mass were found to be 5 and 20 pg for 0.0044 absorbance, respectively. The concentration limit of detection was 0.1 pg/ml for a 50-ml sample, and the linear dynamic range covered three orders of magnitude. The precisions of the measurements were 2.7% for 0.1 ng and 2.6% for 2 ng of mercury. Analyses of NBS and NIES reference materials showed quantitative recovery. Analytical results obtained by the technique are presented for natural waters, marine biota and sediments.     

Hydride Generation Graphite Furnace Atomic Absorption Determination of Bismuth in Clinical Samples with in Situ Preconcentration

A sensitive method for the determination of bismuth in clinical samples using hydride generation/trapping and atomization in a graphite furnace is described. Addition of Pd-Ir to the furnace tube surface before hydride trapping leads to great improvement in the sensitivity of the method. Calibration is achieved with simple aqueous standards carried through this same procedure. An absolute detection limit (3σ) of 100 pg and a concentration detection limit of 20 ng/liter are obtained using 5-ml sample volumes. Corresponding precisions of 8-12% are typical for analyses of these samples. Microwave-assisted sample digestion procedures using HNO₃ and H₂O₂ were used to decompose clinical materials. The method was used to determine Bi in human blood, serum, urine, and tissue before and after intake of therapeutic doses of colloidal bismuth citrate.     

石墨炉原子吸收法测定生物样品中的铊

为建立测定生物样品中铊的石墨炉原子吸收法,通过微波消解,采用基本改进剂,改变石墨炉灰化温度等操作条件,提高了该法的准确度和精密度.结果表明,方法的线性范围为0～100 μg/L;检出限:血为0.10 mg/L;尿为0.02 mg/L;头发为0.20 mg/kg;回收率:血为83.1%～108%;尿为89.6%～105%...     

石墨炉原子吸收分光光度法测定空气中的铍

对300余个样品进行监测,选择灵敏度高的石墨管和最佳基体,提高灰化、原子化的温度,确立了石墨炉原子吸收法测定空气中铍含量的实验条件。样品采用干灰化消解法,最佳溶剂为质量分数l％的硝酸溶液,利用仪器内置的样品浓度计算程序,绘制工作曲线直接获得样品中铍的含量。方法检出限为0．021μg／L,测定结果的相对标准偏差小于2％（n=6）,线性范围为0～6．5μg／L,加标回收率为91．6％～107％。     

流动注射-氢化物-石墨炉原子吸收光谱法应用研究 Ⅲ.痕量锗的测定

本文采用自制的氢化物-石墨炉自动进样器及流动注射仪,直接测定了一些环境试样中的痕量锗,并研究了测定条件。该方法灵敏度高,线性范围宽,操作简单,速度快,耗样量少。特征质量:5.7 pg/0.0044A;检出限:1.3 pg;测定速度:30个样/h;回收率:99.5％～104％。     

Activation analysis of bromine in rock samples

A simple method for the radiochemical neutron activation analysis of bromine in rock samples is described. The irradiated samples are ignited in an induction furnace in a flow of air for four minutes. The bromine expelled is collected onto activated charcoal which is measured using a Ge(Li) detector. The yield of the chemical separation is 85–100% and the detection limit is 7 ppb. The method is discussed and results for the analysis of 14 USGS standard rock samples are presented.     

Determination of bismuth in nickel-base alloys by atomic absorption spectrometry with introduction of solid samples into an induction furnace

Atomic absorption spectrometry with an induction furnace is applicable'to the determination of bismuth at 0.02–10 μg g^-1 levels in 1–30-mg samples of nickel-base alloys dropped into the furnace. Calibration graphs of peak absorbance versus mass of bismuth are constructed by use of standardised alloys. Samples of alloys can be added to the furnace at 2.5-min intervals. Calibration graphs, accuracy, precision and limits of detection of the method are discussed for 26 alloys. Accuracy is assessed by comparing the induction furnace results with results supplied with the alloys, and with results obtained for solutions of the alloys by atomic absorption spectrometry in association with hydride generation or a mini-Massmann furnace. With alloys containing more than 0.1 μg Bi g^-1, relative standard deviations by the induction furnace method are usually < 15%. The limit of detection for bismuth is 0.02 μg g^-1     

固体直接进样石墨炉原子吸收法测定土壤中镉元素

固体直接进样是近年来石墨炉原子吸收分析领域发展较快的技术,它取代了繁冗的对固体样品的前处理,避免了样品的污染和损失,也保护了操作人员的身体健康。采用固体直接进样-石墨炉原子吸收光谱仪,结合使用持久化学改进剂对环境土壤样品中Cd元素进行测定,其结果表明,方法检出限为0.002 66ng,定量测定下限为0.008 87ng,相对标准偏差RSD≤10%,方法准确、可靠,均满足环境土壤测试方法的要求。