Comparison of three digestion methods for the determination of the aqua regia soluble content of lead,cadmium and chromium in sewage sludges by ETAAS

A procedure for the determination of the aqua regia soluble content of lead, cadmium and chromium in a sewage sludge reference material (CRM 145R) by electrothermal atomic absorption spectrometry (ETAAS) is described. A comparison of the dissolution procedure proposed in the certification report, to an oven-assisted digestion and a proposed microwave digestion procedure is performed. In the ETAAS method developed, 1 g of Pt proved to be an appropriate modifier for each of the above heavy metals. Possible sources of error at each analytical step are addressed. The metal contents obtained with the proposed method are in a good agreement at 95% significance level with the certified values given for CRM 145R.     

A neutron activation scheme for the detection and determination of pollutant heavy metals in sewage based fertilizers

A scheme of analysis of heavy metals in sewage based fertilizers, based mainly on direct gamma spectrometry using a Ge(Li) detector, is described. Reversed-phase anion exchange chromatography was used in separating some of the elements with mutually interfering gamma energies. The results are compared with those obtained from atomic absorption and spectrophotometric procedures.     

Direct determination of trace elements in niobium,tantalum and their oxides by inductively coupled plasma atomic emission spectrometry after microwave dissolution

Analytical schemes for the determination of trace elements in high-purity niobium, tantalum and their oxides are proposed. The schemes are based on microwave dissolution of the metals and oxides followed by inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of impurities in the solutions. The possibilities of interelement and off-peak background corrections in ICP-AES analysis are discussed. The accuracy of the results obtained is confirmed by the determination of trace elements after a matrix sorption separation procedure. For a number of elements, a comparison of the results obtained by ICP-AES without and with the matrix separation procedure and by electrothermal atomic absorption spectrometry (ETAAS) shows good agreement. The limits of detection for direct ICP-AES determination are in the range 0.4*1.0 μg g⁻¹ for Ba, Ca, Fe, Mg, Mn, Y and La; between 2.0 and 10.0 μ g⁻¹ for B, Cd, Co, Cr, Cu, Hf, Mo, Na, Nb, Ni, Pb, Sr, Ti, Zr and Ta; and for K, Sb and W a detection limit of 20 μ g⁻¹ is achieved. The schemes proposed are intended for rapid routine analysis.     

Determination of cobalt in sewage sludge using ultrasonic slurry sampling graphite furnace atomic absorption spectrometry

Cobalt in sludge of domestic and industrial origin, with high iron contents (> 17 g/kg), was determined by slurry sampling graphite furnace atomic absorption spectrometry (GF-AAS). Slurries prepared by ultrasonic stirring were adequately diluted to cover the variation in cobalt content in the sludge samples. The diluent was 5% HNO3. Standard atomisation conditions for cobalt determination were used and no matrix modifier was applied. Slurry sampling GF-AAS results in the sludge were verified by analysing totally digested samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) and by GF-AAS. The procedure was validated by analysing the certified reference material BCR 146 R, a sewage sludge of industrial origin. Recoveries for cobalt in the spiked slurried sludge samples ranged from 92 to 96%, with a relative standard deviation of 10%. Recoveries in the certified sludge using slurry sampling GF-AAS technique were about 103% for a cobalt content of 7.39 mg/kg.     

Determination of cobalt in sewage sludge using ultrasonic slurry sampling graphite furnace atomic absorption spectrometry

Cobalt in sludge of domestic and industrial origin, with high iron contents (> 17 g/kg), was determined by slurry sampling graphite furnace atomic absorption spectrometry (GF-AAS). Slurries prepared by ultrasonic stirring were adequately diluted to cover the variation in cobalt content in the sludge samples. The diluent was 5% HNO₃. Standard atomisation conditions for cobalt determination were used and no matrix modifier was applied. Slurry sampling GF-AAS results in the sludge were verified by analysing totally digested samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) and by GF-AAS. The procedure was validated by analysing the certified reference material BCR 146 R, a sewage sludge of industrial origin. Recoveries for cobalt in the spiked slurried sludge samples ranged from 92 to 96%, with a relative standard deviation of 10%. Recoveries in the certified sludge using slurry sampling GF-AAS technique were about 103% for a cobalt content of 7.39 mg/kg.     

Simultaneous determination of Cd,Cr, Cu,Ni, Pb and Zn in sewage sludge by slurry introduction ICP-OES method

In order to evaluate the slurry nebulisation method as an alternative method for analysis of sewage sludge, the metal content of sludge samples of different origins was determined. The concentrations of six elements: Cd, Cr, Cu, Ni, Pb, and Zn were determined by introducing the sludge as a slurry into an inductively coupled plasma optical emission spectrometer (ICP-OES). Calibration was performed by using aqueous standard solutions. For comparison, the sewage sludge was also digested by microwave digestion and introduced into the plasma as an aqueous solution. The accuracy of the method was checked by analysing a sewage sludge certified reference material (CRM 007-040 Sewage Sludge). The Student's t-test showed that values obtained using slurry nebulisation were close to the certified values at a 95% confidence level. The values of elements Cd 11.1?±?0.8; Cr 37.7?±?3.3; Cu 563.3?±?38.4; Pb 119.2?±?10.1; Zn 729?±?68.2?mg?kg^?1 obtained using this method were comparable with those obtained using the conventional method. The slurry method can, therefore, be successfully applied to the determination of content of each element in sewage sludge with RSD less than 3%, without the need to predissolve them. This could avoid the use of hazardous chemicals, incomplete dissolution and loss of volatile analytes.     

TS-FF-AAS and multivariate calibration: A proposition for sewage sludge slurry sample analyses

This work describes a methodology for Cd and Pb determination in sewage sludge slurry samples using thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). The TS-FF-AAS system was equipped with a Ni tube atomizer placed on an oxidizing air/acetylene flame. Two multivariate calibration models based on partial least squares (PLS) were proposed using total peak profiles (recorded during 57 s). Metals concentration in the sewage sludge samples were from 1.87 to 6.26 mg kg⁻¹ for Cd and from 101 to 327 mg kg⁻¹ for Pb. The limits of detection and quantification were, respectively, 0.2 and 0.7 μg kg⁻¹ for Cd and 8 and 26 μg kg⁻¹ for Pb. These values were three times lower than the limits found when these metals were calibrated using linear calibration with aqueous standard solutions.     

Comparison of electrothermal atomic absorption spectrometry of the metal content of sewage sludge with flame atomic absorption spectrometry in conjunction with different pretreatment methods

Determination of the metal content of sewage sludges is of increasing importance in order to assess the suitability of the sludge for disposal to agricultural land. The methods currently used for the determination of cadmium, chromium, copper, nickel, lead and zinc are time-consuming. A rapid electrothermal atomic absorption procedure with homogenization as the only pretreatment is compared with wet and dry pretreatment methods followed by flame atomic absorption spectrometry, in a statistically designed experiment. The precision of the rapid electrothermal atomic absorption procedure compares well with flame atomic absorption in conjunction with all pretreatment methods used. Time saved by the use of this method is substantial; the procedure could be used advantageously for routine analysis.     

Determination of mercury in sewage sludge by direct slurry sampling graphite furnace atomic absorption spectrometry

Ultrasonic slurry sampling electrothermal atomic absorption spectrometry (ETAAS) method was elaborated to the determination of Hg in sewage sludge samples with the use of KMnO₄+Pd modifier. The minimum sample amount required for slurry preparation with respect to sample homogeneity was evaluated by weighting masses between 3 and 30 mg directly into the autosampler cups. Validation of the proposed method was performed with the use of Certified Reference Materials of sewage sludge, CRM 007-040 and CRM 144R. Two sewage sludge samples from Poznañ (Poland) city were analysed using the present direct method and a method with sample digestion, resulting in no difference within statistical error.     

Determination de l'etain dans les sediments et les boues de stations d'epuration par spectrometrie d'absorption atomique avec generation d'hydruresDetermination of tin in sediments and sewage sludges by atomic absorption spectrometry with hydride generation.

The conditions for the determination of tin in sediments and sewage sludges by atomic absorption spectrometry with hydride generation are evaluated. Hydride generation is achieved in a 0.4 M nitric acid/0.2 tartaric acid solution. The effects of hydrochloric, nitric, sulfuric and hydrofluoric acids are discussed. Matrix effect and interferences from other trace elements are studied. Seven sample decomposition procedures are compared. Refluxing with a (1 + 3) niric acid/hydrochloric acid mixture was the preferred procedure for decomposing such samples.     

Cloud point extraction utilizable for separation and preconcentration of (ultra)trace elements in biological fluids before their determination by spectrometric methods: a brief review

This review summarizes and discusses applications related to the determination of (ultra)trace elements in biological fluids using cloud point extraction as sample pretreatment technique. Biological fluids, such as urine, whole blood, serum or plasma, are the most often analyzed biological materials in these applications. Spectrometric methods, such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry, and inductively coupled plasma mass spectrometry, are commonly used for quantification of elements preconcentrated by the extraction technique. Optimized extraction procedures lead to the high extraction recoveries of the target analytes. High enrichment factors achieved lead to the lowering of quantification limits. All these achievements illustrate the great potential of extractions for reliable quantification of (ultra)trace elements in complex biological matrix what is documented in this review of a number of works published on this topic.     

Determination of zinc, cadmium, lead and copper in soils and sewage sludges by microprocessor-controlled voltammetry in comparison with atomic absorption spectrometry

Summary Information on the heavy metal contents in soils and sewage sludges is of strong ecological interest. For control of the maximum allowed concentrations photometric and atomic absorption spectrometric methods have been developed for the determination of the single elements; sample digestion is carried out using hydrochloric acid and nitric acid.Differential pulse polarography and differential pulse anodic stripping voltammetry allow the simultaneous determination of different heavy metals in one digestion solution according to their electrochemical behaviour. This possibility is given, for instance, for zinc, cadmium, lead and copper. The adequate procedure was tested with a microprocessor-controlled polarograph. Flame atomic absorption spectrometry was used as reference method.

---

Bestimmung von Zink, Cadmium, Blei und Kupfer in Böden und Klärschlämmen durch mikroprozessorgesteuerte Voltammetrie im Vergleich mit der Atomabsorptionsspektrometrie

     

Some observations on the determination of total heavy metals in sewage sludge by atomic absorption spectrophotometry after a pressurized acid digestion

An economical and simple method for the flame atomic absorption spectrometric determination of Cd, Pb, Ni, Cu, Fe, and Zn in sewage sludges is described. Samples are treated with concentrated HNO₃ in a thermal oven using Pyrex glass tubes hermetically sealed with Bakelite screw caps. The effect of the digestion parameters, such as digestion time, acid volume, sample mass, and temperature, were studied. The precision and accuracy of this procedure were evaluated by the analysis of two BCR (Community Bureau of Reference, European Communities) certified sewage sludge samples (CRM 146 and 144).     

Atomiser, source, inductively coupled plasmas, in atomic fluorescence spectrometry (ASIA). Some recent work

The dual-plasma atomic fluorescence/atomic emission spectrometer (ASIA spectrometer) is described and the detection limits for several elements in both the fluorescence and the emission mode are presented and compared directly. The detection limits for the non-refractory elements are, in general, better in fluorescence than emission While for the refractory elements the converse is true, but all are in the ng ml⁻¹ range. Growth curves for a refractory and a non-refractory element are presented and evaluated.     

Microwave induced plasma atomic emission spectrometry: a suitable detection system for the determination of volatile halocarbons

Microwave induced plasma atomic emission spectrometry (MIP-AES), a highly sensitive detection system for organometal compounds, was coupled to an automated purge and trap gas chromatographic system for the determination of volatile halogenated hydrocarbons in environmental water samples. Optimisation of the parameters affecting the injection and detection system led to relative detection limits from 1 to 14 ng · L^–1 for chlorine- and bromine-compounds and from 10 to 75 ng · L^–1 for iodine-compounds, on basis of a 10 mL sample volume. A comparison of the analytical characteristics between atomic emission detection (AED) and electron capture detection (ECD) showed a lower sensitivity of the atomic emission detector for halocarbons, but the detection thresholds are low enough to use the method for the determination of volatile halocarbons in trace level concentrations. The ability of the atomic emission detector provides increased selectivity for monitoring individual halogenated compounds under simplified and rapid chromatographic conditions, within a total analysis time of only 30 min. The method was applied with gas chromatographic separation for the analysis of sea water samples. Concentrations for the different elements between 0.05 and 15.28 μg · L^–1 were determined.     

On-line microwave oven digestion flame atomic absorption analysis of solid samples

A manifold has been developed for on-line microwave oven digestion and flame atomic absorption spectrometric (FAAS) determination of metallic elements in solid samples. The use of a closed flow system permits sample treatment before analysis by FAAS, the direct injection of slurries avoids a filtration step and the interconnection of two conventional rotary injection valves allows the rapid introduction of samples and standards. The determination of lead in sewage sludge was employed as a test system for the proposed on-line sample digestion manifold. The procedure has a limit of detection of 0.2 μg Pb g^?1.     

Developing electrodeposition techniques for preconcentration of ultra-traces of Ni, Cr and Pb prior to arc-atomic emission spectrometry determination

Electrodeposition is known to be proper for separation and preconcentration of extremely low concentrations of analytes from the bulk sample which is instrumentally very simple. In the present research, a combination of electrodeposition with arc atomic emission spectrometry (ED-AAES) method has been developed in order to improve the analytical performance of this spectrometry technique. The results show that sensitivity and detection limits by using ED-AAES were improved 1000–2000 folds over those of normal arc atomic emission spectrometry in determination of the selected elements. The detection limits for measurement of Ni, Cr and Pb were 2.56, 3.05 and 2.11 µg L^{− 1} for monodeposition and 3.31, 3.72 and 3.25 µg L^{− 1} for simultaneously deposition, respectively. The precision of determination was in the range of 2–4% RSD. Typical calibration graphs for these elements were linear up to 100 µg L^{− 1}, depending on the element and matrix.Application of this technique was also tested on determination of the studied elements in an electroplating plant's waste water. The accuracy of technique was verified by comparing the results of the waste water analysis with those of electrothermal atomic absorption spectroscopy as a reference standard method.The obtained results show that the combined technique (ED-AAES) has been progressed substantially toward the ultimate goal of direct interference-free determination of trace analysis in complex samples by AAES.     

Automatic flow-injection system for the determination of heavy metals in sewage sludge by microwave digestion and detection by inductively coupled plasma-atomic emission spectrometry (MW-ICP/AES)

Results are shown obtained in the optimization of an automatic flow injection system that combines microwave digestion with atomic spectrometric detection (FAAS, ICP/AES) for the determination of heavy metals in sewage sludge. Digestion is performed by preparing a suspension of the sample in 1.5 mol/l HNO₃ and making it flow through a PTFE capillary tube placed inside a conventional microwave oven. The effects of the length and inner diameter of the capillary tube, as well as that of the pumping rate, have been studied in order to find the experimental conditions that allow a quantitative elemental recovery in the shortest period of time possible. The optimization study was carried out on a certified sample (BCR No. 146), and the elements determined were Zn, Cu, Pb, Cd, Ni and Cr. The experimental data (percent recovery vs. digestion time) have been fitted to a mathematical model in order to quantify the influence of each of the variables studied. The optimized procedure (MW-ICP/AES) has been applied to one ordinary and one certified sewage sludge sample. In comparison with the conventional methods of sewage sludge analysis, the one proposed is less time consuming, while being equally precise and accurate.     

Operation of a proficiency testing scheme of trace elements in sewage sludge with reference values

A proficiency test (PT) was carried out to investigate the quality of laboratory results measuring trace elements in sewage sludge. The scheme relied on reference values, established through flame atomic absorption spectroscopy and instrumental neutron activation analysis. Within the framework of the project, ”Proficiency testing in Central and Eastern European Countries”, the measurements were done in parallel using induced coupled plasma mass spectrometry. This paper discusses the design of the PTS, the metrological concepts behind it and the way in which it was operated. The discussion includes the estimation of measurement uncertainty of the reference values obtained, homogeneity testing and its uncertainty evaluation, as well as all relevant quality assurance aspects. From the results, it can be concluded that all measurement methods involved agree within their respective uncertainties. Furthermore, it can be concluded that it is feasible to operate a proficiency test of trace elements in sewage sludge using reference values. The agreement between the reference values and the consensus values is satisfactory.     

Free-atom formation processes in premixed fuel-rich and stoichiometric oxygen-acetylene flames employed in atomic emission and absorption spectroscopy

Detailed observations on the atomic and molecular absorption and emission spectra of the various zones of premixed oxyacetylene flames are presented. Spatial flame profile data for both the natural flame species and those formed when solutions of metallic salts are nebulized into the flame are interpreted in terms of: (a) the relative concentrations of reactive intermediate and stable species in the various zones; (b) the mechanism of free-atom formation from aerosol droplets; and (c) free-atom depopulation processes. The results of this study clearly show that the striking enhancement in atomic spectra observed in either absorption or emission for many elements in the fuel-rich oxyacetylene flame originate in the favorable chemical environment provided by the interconal zone for the formation and existence of free-atoms.