Determination of lead in fly-ash from a garbage incinerator by atomic-absorption and x-ray fluorescence spectrometry

The lead content in fly-ash collected by an electrostatic precipitator has been determined by atomic-absorption spectrometry (AAS) after decomposition by four different leaching/dissolution techniques, and also determined by X-ray fluorescence spectrometry (XRFS) by the standard-addition method. The XRFS data were evaluated by non-linear regression since the standard additions affected the attenuation coefficient of the sample. Good agreement was obtained between the results obtained with AAS and XRFS. It is concluded that lead is quantitatively extracted by hot 1M nitric acid or treatment with hydrofluoric acid/nitric acid. Direct measurement of briquetted samples by XRFS is suggested for rapid monitoring of the lead content in fly-ash from garbage incineration.     

A modified standard addition method in X-ray fluorescence spectrometry

A modified standard addition method for single element determination by X-ray fluorescence spectrometry has been studied. The attenuation properties of the standard added samples are kept constant by adding decreasing amounts of an attenuation modifier along with increasing amounts of a standard. In this way the standard addition curve will be a straight line in cases where the ordinary standard addition curve is non-linear, and linear regression can be used to evaluate the concentration of the analyte. Standard additions of oxides of a number of elements, with and without modifier, have been made to cellulose powder or a mixture of aluminium oxide and polyethylene as matrices in order to test the method. The method has been applied to the determination of zinc in fly-ash from a steel work and of iron in cement. The fly-ash contained about 5% of zinc and the cement samples between 2 and 5% of Fe(2)O(3). The results were compared with those obtained by ICP-AES after decomposition of samples in lithium tetraborate or lithium metaborate and dissolution of the melt in 10%(v/v) nitric acid. The results agreed within 2%, relative, for fly-ash and within 3-6%, relative, for cement samples.     

Determination of bromine, chlorine, sulphur and phosphorus in peat by X-ray fluorescence spectrometry combined with single-element and multi-element standard addition

Bromine (20-40 ppm), chlorine (200-500 ppm), sulphur (0.2-3%) and phosphorus (300-1000 ppm) in peat have been determined by X-ray fluorescence spectrometry (XRFS) combined with the standard-addition method. Chlorine, sulphur and phosphorus have also been determined by other methods and agreement between the results is good. Theoretical calculations based on the Sherman equation were made to validate the linearity of the standard-addition curves. A multi-element standard-addition technique has been tested with addition of all elements at the same time. The results for chlorine were high but after correction for the difference in attenuation coefficient between the sample and added compound the results agreed with those from single-element standard addition.     

Standard-addition procedure for the determination of traces of lead in solid samples by x-ray fluorescence spectrometry

A standard-addition procedure for analysis of powdered solid samples by energy-dispersive X-ray fluorescence is described. Different amounts of the element to be determined are added to 4–6 specimens of the unknown sample. The spiked samples are prepared by mixing the powdered sample with an aqueous standard solution and drying the mixture. Homogeneously spiked samples are thus obtained with analyte and spike concentrations at the ppm level. The procedure has been investigated theoretically, and it is found suitable for the quantitative determination of lead at the ppm level. The accuracy of the technique for traces of lead has been tested on solid reference materials for the determination of lead. The quantitative results obtained compare well with those found by potentiometric stripping analysis.     

微波辅助消解-原子荧光法测定玻璃中的镉砷铅

光学玻璃中的各种元素对玻璃的光学性能有不同的影响。如加入镉可以提高玻璃折射率;砷的引入能增加玻璃的透光度,含铅玻璃具有低成本、高折射性等优点。但是镉、砷、铅均为有毒元素,玻璃加工和处理过程以及毒废弃物的处理都可能引起水、土壤、大气的污染并给人体带来一定的危害     

A simplified approach to the generalized standard-addition method and its application in electrothermal atomic absorption spectrometry

A simple and general standard-addition method for a single-component determination is presented. The method uses two independent variables for the calculation of the analyte concentration (the amount of sample taken and the amount of analyte added) and one dependent variable, the response. The sensitivity and the response of the blank can also be estimated from the model by changing the amount of the sample and the amount of the analyte addition. In the simples case, a linear equation is assumed to exist between the variables. Geometrically, the model can be expressed by the response plane in the variable-space. The method has all the advantages of the ordinary standard-addition method but also includes automatic blank elimination and versatile matrix-interference control. Two examples of the use of the method are based on graphite-furnace atomic absorption spectrometry of chromium and lead. Standard statistical packages are applied.     

Energy dispersive X-Ray fluorescence determination of thorium in phosphoric acid solutions

Energy dispersive X-ray fluorescence studies on determination of thorium (in the range of 7 to 137 mg/mL) in phosphoric acid solutions obtained by dissolution of thoria in autoclave were made. Fixed amounts of Y internal standard solutions, after dilution with equal amount of phosphoric acid, were added to the calibration as well as sample solutions. Solution aliquots of approximately 2–5 µL were deposited on thick absorbent sheets to absorb the solutions and the sheets were presented for energy dispersive X-ray fluorescence measurements. A calibration plot was made between intensity ratios (Th Lα/Y Kα) against respective amounts of thorium in the calibration solutions. Thorium amounts in phosphoric acid samples were determined using their energy dispersive X-ray fluorescence spectra and the above calibration plot. The energy dispersive X-ray fluorescence results, thus obtained, were compared with the corresponding gamma ray spectrometry results and were found to be within average deviation of 2.6% from the respective gamma ray spectrometry values. The average precision obtained in energy dispersive X-ray fluorescence determinations was found to be 4% (1σ). The energy dispersive X-ray fluorescence method has an advantage over gamma ray spectrometry for thorium determination as the amount of sample required and measurement time is far less compared to that required in gamma ray spectrometry.     

前表面荧光光谱法快速测定洗涤剂中荧光增白剂的迁移量

建立了测定洗涤剂中荧光增白剂迁移量的前表面荧光光谱法,以玻璃纤维纸为吸附材质,洗涤剂样品中的荧光增白剂迁移到吸附材质上,用自行研制的前表面荧光光谱仪直接测量吸附材质.测定荧光增白剂的线性范围为10.0~500.0μg/kg,检出限为2.8μg/kg.分析了96种洗涤剂,其中发现12种洗涤剂有荧光增白剂迁移.与国标方法——目视法进行了比较,结果一致.本方法简单、快速、准确,可用于不同种类洗涤剂中荧光增白剂迁移量的测定.     

Determination of trace amounts of copper in water samples by flame atomic absorption spectrometry after preconcentration on octadecyl-bonded silica membranes modified by a Di-Schiff base ligand

A simple method for rapid extraction-preconcentration and determination of trace amounts of copper(II) ions in water samples by using octadecyl-bonded silica membranes modified by a Schiff base, named bis(5-chloro-2-hydroxyacetophenone)-1,2-propanediimine (L), followed by flame atomic absorption spectrometry (FAAS) is described. The effect of parameters influencing the extraction efficiency, i.e. pH of the sample solution, amount of the modifier, type and volume of stripping reagent, and sample and stripping reagent flow rates were evaluated and optimized. The detection limit and the concentration factor of the presented method are 10.2 ng/L and greater than 400, respectively. Under optimum experimental conditions the capacity of the membrane disks modified by 4 mg of the ligand was found to be 142.8 (±0.2) μg of copper. The method was applied to the enrichment and determination of copper content in different natural water samples.     

Solid phase extraction and determination of lead in soil and water samples using octadecyl silica membrane disks modified by bis[1-hydroxy-9,10-anthraquinone-2-methyl]sulfide and flame atomic absorption spectrometry

A simple, reliable and relatively fast method has been developed to selectively separate and concentrate trace amounts of lead from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through an octadecyl-bonded silica membrane disk modified by a recently synthesized bis(anthraquinone)sulfide, Pb(2+) ions adsorb quantitatively and almost all matrix elements will pass through the disk to drain. The retained lead ions are then stripped from the disk by minimal amount of acetic acid as eluent. The proposed method permitted large enrichment factors of about 300 and higher. The limit of detection of the proposed method is 50 ng Pb(2+) per 1000 ml. The effects of various cationic interferences on the recovery of lead in binary mixtures were studied. The method was successfully applied to the determination of lead in soil and water samples.     

Determination of copper, iron, manganese, lead and cadmium in automatically wet-digested animal tissue by graphite-furnace atomic-absorption spectrometry with zeeman background correction

An efficient wet digestion method is described which allows the determination of various elements in animal tissues. Copper, iron, manganese, lead and cadmium in one dilution of the digested sample can be determined by means of graphite-furnace atomic-absorption spectrometry, with Zeeman background correction. Tests with the National Bureau of Standards Bovine Liver SRM as reference gave analytical results, obtained with calibration graphs as well as by the standard-addition method, which agreed well with the certified values.     

Determination of lead in aluminum and magnesium antacids using electrothermal atomic absorption spectrometry

This paper proposes a method for the determination of lead in aluminum and magnesium antacids employing electrothermal atomic absorption spectrometry (ET AAS). The pyrolysis and atomization temperatures established during the optimization step were 700 and 2200 °C, respectively, using phosphate as the chemical modifier. Under these conditions, a characteristic mass of 25 pg, and limits of detection and quantification of 0.40 and 1.35 μg L⁻¹, respectively were obtained. Some experiments demonstrated that the calibration can be performed employing the external calibration technique using aqueous standards. The precision expressed as relative standard deviation (RSD %) was 4.03% for an antacid sample with lead concentrations of 284.5 μg L⁻¹. The proposed method was applied for the determination of lead in five antacid samples acquired in Salvador City, Brazil. The lead content was varied from 87 to 943 μg g⁻¹. The samples were also analyzed after complete dissolution by inductively coupled plasma mass spectrometry (ICP-MS). No statistical difference was observed between the results obtained by both of the procedures performed.     

Determination of indium by graphite furnace atomic absorption spectrometry after coprecipitation with chitosan.

A sensitive and simple method for the determination of trace amounts of indium in water samples by graphite furnace atomic absorption spectrometry (GFAAS) after coprecipitation with chitosan was investigated. Indium was quantitatively preconcentrated from water samples by coprecipitation with chitosan at pH 7.0-9.0. The coprecipitant was easily dissolved with acetic acid, and indium in the resulting solution was determined by GFAAS. The addition of lanthanum as a chemical modifier was more effective for the atomic absorbance of indium. The detection limit (S/N > or = 3) for indium was 0.04 microg dm(-3), and the relative standard deviations (n = 5) were 3.5-4.5% at 1.0 microg/100 cm3. The results obtained in this study indicate that the proposed method can be successfully applied to the determination of trace indium in water samples.     

Solid-phase extraction and determination of ultra trace amounts of lead,mercury and cadmium in water samples using octadecyl silica membrane disks modified with 5,5′-dithiobis(2-nitrobenzoic acid) and atomic absorption spectrometry

A simple and fast method for preconcentration and determination of ultra trace amounts of lead(II), mercury(II) and cadmium(II) in water samples is presented. Lead, mercury and cadmium adsorbed quantitatively during passage of water samples (pH?=?7, flow rate?=?20 mL min^?1) through octadecyl silica membrane disks modified with 5,5′-dithiobis(2-nitrobenzoic acid). The retained lead, mercury and cadmium are then stripped from the disk with a minimal amount of 1 M hydrochloric acid solution as eluent, and determined by atomic absorption spectrometry. The influence of flow rates of the eluent and sample solution, the amount of ligand, type and least amount of eluent, pH of sample, effect of other ions and breakthrough volume are determined. The breakthrough volume of the method is greater than 2000 mL for lead and greater than 1500 mL for mercury and cadmium, which results in an enrichment factor of 200 for lead and an enrichment factor of 150 for both mercury and cadmium. The limit of detection of the proposed method is 177, 2 and 13 ng l^?1 for lead, mercury and cadmium, respectively.     

Microwave sample-digestion procedure for determination of arsenic in moss samples using electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry

Arsenic in moss samples was determined by electrothermal atomic absorption spectrometry (ETAAS) after microwave-assisted sample digestion. Two different sample masses (500 mg and 1000 mg) and three different microwave ovens were used in the digestion. There was a slight difference in the digestion efficiency, as determined by the residual carbon concentrations of 500 mg digested samples, between the microwave ovens. The arsenic results obtained for moss reference samples were, in most cases, satisfactory. However, phosphorus was found to have a reducing influence on the arsenic peak area in the ETAAS determination. According to the results, it was not possible to reduce the phosphorus interference by increasing the amount of Mg(NO(3))(2) in the Pd-Mg chemical modifier. The arsenic results obtained by ETAAS were compared to those obtained by inductively coupled plasma mass spectrometry (ICP-MS).     

Quantification in MALDI-TOF mass spectrometry of modified polymers

MALDI-TOF mass spectrometry quantification is hampered by the poor reproducibility of the signal intensity and by molecular-mass and compositional discrimination. The addition of a suitable compound as an internal standard increases reproducibility and allows a calibration curve to be constructed. The concept was also verified with synthetic polymers but no instructions for practical implementation were given [H. Chen, M. He, J. Pei, H. He, Anal. Chem. 75 (2003) 6531-6535.], even though synthetic polymers are generally non-uniform with respect to molecular mass and composition and access to the polymer of the same molecular mass distribution and composition as that of the quantified one is thus the exception rather than rule. On the other hand, relative quantification of polymers e.g., the content of the precursor polymer in a batch of a modified polymer, is usually sought. In this particular case, the pure precursor is usually available and the modified polymer can serve as an internal standard. However, the calibration curve still cannot be constructed and the use of the internal standard has to be combined with the method of standard addition in which the precursor polymer is added directly to the analyzed sample. The experiments with simulated modified polymers, mixtures of poly(ethylene glycol) (PEG) and poly(ethylene glycol) monomethyl ether (MPEG) of similar molecular-mass distribution, revealed a power dependence of the PEG/MPEG signal-intensity ratio (MS ratio) on the PEG/MPEG concentrations ratio in the mixture (gravimetric ratio). The result was obtained using standard procedures and instrumentation, which means that the basic assumption of the standard-addition method, i.e., the proportionality of the MS and gravimetric ratios, generally cannot be taken for granted. Therefore, the multi-point combined internal-standard standard-addition method was developed and experimentally verified for the quantification of the precursor in modified polymers. In this method, the two parameters of the power-type calibration curve - the proportionality constant and the exponent-are assumed. If the exponent strongly deviates from unity the minority component can be significantly underrepresented in the spectrum. Therefore, the absence of the precursor polymer signals in the MALDI-TOF mass spectrum of a modified polymer sample does not prove the absence of the precursor in the sample. Such a conclusion has to be corroborated by the standard-addition method.     

Determination of cobalt, copper, iron, nickel and zinc in cemented tungsten carbides with cobalt as a binder by FAAS: Matrix effect control by multivariate technique

A new approach for the determination of cobalt, copper, iron, nickel and zinc in cemented tungsten carbides with cobalt as a binder by flame atomic absorption spectrophotometry (FAAS) is reported. Real samples were dissolved in phosphoric, hydrochloric and nitric acid. PTFE bomb or alternatively small amounts of HF were used for the enhancement of the recovery of the elements investigated. Synthetic samples were used for interference studies. Multiple linear regression was applied for the control of matrix effects and it proved to be very effective in the search for interfering elements. Using simple acid based standards, all investigated elements could be determined sequentially in a complex matrix by using an appropriate method of calculation. The method described has been succesfully applied to real type commercial samples. Results were compared with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) and X-ray fluorescence spectrometry (XRF), being in good agreement with each other and having relative standard deviations better than 5%.     

Determination of lanthanum, cerium, praseodymium and neodymium in alloy steels by inductively coupled plasma atomic-emission spectrometry

Inductively coupled plasma spectrometry has been applied to the determination of La, Ce, Pr and Nd in alloy steels. Spectral interference by other alloying elements as well as by the lanthanides themselves was studied. The influence of other lanthanides on the Pr and Nd lines could be dealt with by correction equations. It was found that within the range of concentrations corresponding to mild alloy steel, at least one of the lines selected for determining the lanthanides was free from interferences. The detection limits for La, Ce, Pr and Nd in steel were 5 x 10(-5), 1.5 x 10(-4), 1 x 10(-4) and 2.4 x 10(-4)% respectively. The procedure was tested on standard samples and by the standard-addition method.     

Determination of lead in fish samples by slurry sampling electrothermal atomic absorption spectrometry

Ultrasonic slurry sampling electrothermal atomic absorption spectrometry (USS-ETAAS) was been applied to the determination of lead in several fish samples. The influences of instrument operating conditions and slurry preparation on the signal were examined. Palladium and ammonium nitrate were used as the modifier to improve the signal. Since the sensitivity to lead in various fish slurries and aqueous solutions was different, the standard additions method was used for the determination of lead in these fish samples. The method was applied to the determination of lead in dogfish muscle reference material (DORM-2) and a swordfish muscle sample purchased from the local market. The analysis results agreed with the reference value. The accuracy was better than 6%. The precision between sample replicates was better than 16% with the USS-ETAAS method. The detection limit of lead estimated from standard additions curve was about 0.053-0.058 microgram g-1 in different samples.     

Direct determination of lead in polluted sea water by carbon-furnace atomic absorption spectrometry

A simple and rapid method is described for the direct determination of lead in polluted sea water by carbon furnace atomic absorption spectrometry. Filtered sea water is diluted (1+1) with'deionised distilled water and ammonium nitrate is added to act as a matrix modifier. Aliquots of this mixture are injected into a tantalum-coated graphite tube in a HGA-2200 furnace atomiser operated under gas-stop conditions. With the standard addi- tion method, a detection limit (20) of 1 μg Pb 1^-1 is achieved. Good agreement between the proposed method and results obtained by anodic stripping voltammetry was achieved for samples taken from the Firth of Forth.