Furnace Atomization Plasma Emission Spectrometry Research Articles

Vapor generation coupled with furnace atomization plasma emission spectrometry for detection of mercury

Download options Please wait... Article information DOI https://doi.org/10.1039/B814401J Article type Technical Note Submitted 19 Aug 2008 Accepted 11 Dec 2008 First published 11 Feb 2009 Download Citation J. Anal. At. Spectrom., 2009,24, 689-694 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Vapor generation coupled with furnace atomization plasma emission spectrometry for detection of mercury A. S. Ribeiro, M. A. Vieira, P. Grinberg and R. E. Sturgeon, J. Anal. At. Spectrom., 2009, 24, 689 DOI: 10.1039/B814401J To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Anderson S. Ribeiro Mariana A. Vieira Patricia Grinberg Ralph E. Sturgeon

Solid phase microextraction capillary gas chromatography combined with furnace atomization plasma emission spectrometry for speciation of mercury in fish tissues

The use of solid phase microextraction in conjunction with tandem gas chromatography–furnace atomization plasma emission spectrometry (SPME–GC–FAPES) was evaluated for the determination of methylmercury and inorganic mercury in fish tissue. Samples were digested with methanolic potassium hydroxide, derivatized with sodium tetraethylborate and extracted by SPME. After the SPME extraction, species were separated by GC and detected by FAPES. All experimental parameters were optimized for best separation and analytical response. A repeatability precision of typically 2% can be achieved with long-term (3 months) reproducibility precision of 4.3%. Certified Reference Materials DORM-2, DOLT-2 and TORT-2 from the National Research Council of Canada were analyzed to verify the accuracy of this technique. Detection limits of 1.5 ng g −1 for methylmercury and 0.7 ng g −1 for inorganic mercury in biological tissues were obtained.

A comparison of alkyl derivatization methods for speciation of mercury based on solid phase microextraction gas chromatography with furnace atomization plasma emission spectrometry detection

Several derivatizing agents were evaluated for use in speciating mercury in biological samples using solid phase microextraction in conjunction with tandem gas chromatography-furnace atomization plasma emission spectrometry (SPME-GC-FAPES). Following digestion with methanolic potassium hydroxide, the pH of the samples was adjusted and NaCl added when necessary. The mercury species were then derivatized with sodium tetraphenylborate or sodium tetrapropylborate and extracted by SPME using a 100 µm PDMS coated fiber. The derivatized species were then separated by GC and detected by FAPES. All experimental parameters were optimized for best separation and analytical response. Propylation proved to be more sensitive, robust and faster than ethylation or phenylation, leading to procedural detection limits of 0.55 ng g−1 for methylmercury, 0.34 ng g−1 for ethylmercury and 0.23 ng g−1 for inorganic mercury. An intra-day and intra-fiber precision of typically 2.2% was achieved whereas long-term (4 months) and inter-fiber reproducibility precision was typically 4.4%. The accuracy of the method was validated by the analysis of Certified Reference Materials (DORM-2, DOLT-2 and TORT-2) from the National Research Council of Canada.

Iridium as a permanent modifier for determination of cadmium and lead in sediment and biological samples by furnace atomization plasma emission spectrometry

The use of iridium as a permanent modifier for the determination of lead and cadmium in marine sediment and biological tissues by furnace atomization plasma emission spectrometry (FAPES) was evaluated. The Ir coating procedure, atomization conditions and FAPES parameters were optimized for best analytical response and minimum background signal. Good precision (less than 3% RSD) can be achieved with the proposed method. Certified Reference Materials from the National Research Council of Canada were analyzed to verify the accuracy of this technique. Matrix interference was compensated for by the use of standard additions calibration and good agreement was achieved between found and certified values. Detection limits of 3.8 ng g−1 for Pb and 4.0 ng g−1 for Cd in MESS-3 and PACS-2 marine sediment and 4.1ng g−1 for Pb and 2.2 ng g−1 for Cd in DOLT-2 and TORT-2 biological tissues were obtained.

Furnace atomization plasma emission spectrometry with He/Ar mixed gas plasmas

The influence of plasma gas composition on the operating and analytical characteristics of a furnace atomization plasma emission source (FAPES) is presented. He I and Ar I excitation temperatures increase 30% in the mixed gas plasmas whereas argon ion excitation temperatures decrease from 33 000 K to 26 000 K in the presence of He. Collisional exchange of internal energy between excited states of Ar and He accounts for these changes. Average analyte ionization temperatures (for Cr, Mn, Mg, Co, Fe, Cd and Zn), derived from the relative emission intensities of their ionic and atomic lines in a 40-MHz 50-W plasma, increase from 5270 K to 6740 K with the addition of Ar to He. Ionic line intensities increase from 10-fold (Mn) to 40-fold (Cd, Zn) with addition of Ar to the plasma while atomic line intensities increase only twofold. Limits of detection remain substantially unaltered for atomic transitions due to increased noise but are improved twofold (Cd) to 24-fold (Mn) for ionic transitions. The analytical advantages and disadvantages of mixed gas plasmas are discussed. The Ne I excitation temperature at 40 MHz and 50 W was determined to be 4330±80 K.

Influence of plasma gas composition on analyte ionization in furnace atomization plasma emission spectrometry

F. Sun and R. E. Sturgeon, J. Anal. At. Spectrom., 1999, 14, 901 DOI: 10.1039/A900273A

Effects of Bias Voltage and Easily-ionized Elements on the Spatial Distribution of Analytes in Furnace Atomization Plasma Emission Spectrometry

The effect of bias voltage and the presence of easily-ionized elements (EIEs) on the spatial distribution of excited-state atoms and ions of Cu, Ag, Cs and Ca in furnace atomization plasma emission spectrometry is presented. The dc bias of the centre electrode significantly affects the spatial distribution of He I, Cu I, Ag I, Cs I, and Ca II emission in the absence of EIEs. A reasonably uniform distribution of excited-state analyte atoms over the central cross-section of the tube occurs when the centre electrode is self-biased during the course of an atomization transient. A depleted area of Cs I emission around the centre electrode coupled with enhanced Ca II emission in the same region reveals that ionization of analytes is most pronounced in this region. With positive dc bias, concentric rings of enhanced emission occur between the centre electrode and the tube wall for analyte atoms and the He I plasma gas, although the overall breadth of analyte emission distribution is decreased. With NaCl, NaNO 3 and CsCl serving as EIEs, analyte emission from Ag I, Cu I and Ca II in the region between the centre electrode and the tube wall is strongly suppressed with self-bias. The degree of the suppression depends on the extent of vapour cloud overlap between analyte and EIE. In general, equimolar amounts of NaNO 3 and CsCl suppress analyte emission similarly and both produce a greater suppression than NaCl. Equal amounts of Fe, added as an interfering matrix, produces a suppression of analyte emission similar to that of EIEs, suggesting that the primary cause of suppression is the loss of energy from the plasma (as photons) due to excitation and ionization of matrix vapour. Control of the dc bias enhances the radial distribution of excited analyte atoms in the presence of EIEs and Fe, but only at low (≤2 µg) interferent loadings.

Gas-phase re-distribution of analyte species in the integrated contact cuvette furnace atomization plasma emission spectrometry source

Interactions of molecular and atomic analyte species released from the primary site of deposition of the sample into a heated integrated contact furnace have been studied with furnace atomization plasma emission spectrometry. With a 30 W forward power plasma, double peaks are observed in atomic emission during atomization of Cd, Pb, Ag, Mn, Cu, Fe and Co, reflecting early release of analyte from both the wall (primary site of deposition) and, subsequently, the radiationally-heated centre electrode (secondary release). With increased r.f. power, there is a corresponding early shift in all emission transients, reflecting plasma induced heating of both the tube wall and the centre electrode. At higher r.f. power, the centre electrode temperature is sufficient to prevent condensation of molecular species of Cd and Pb with the result that the second (late) peak for these elements is eliminated. Similarly, when the primary site for analyte deposition is the centre electrode, and the r.f. power is 50 W or more, transfer of analyte occurs and secondary release from the tube wall is observed. A directed internal convective flow of plasma gas in the char stage has a significant effect on this process.

Easily ionized element interference effects in furnace atomization plasma emission spectrometry

The effects of easily ionized element (EIE) matrices on the response in furnace atomization plasma emission spectrometry is reported. Using NaCl and CsCl as model matrices, interference on integrated emission intensity from Pb and Co was studied as a function of EIE mass and source pressure [200–1500 Torr (1 Torr = 133.322 Pa)] in a 50 W He r.f. plasma. Comparative response was measured in the same source using the AAS mode of operation. Radiative power losses from the plasma due to excitation of the EIE matrix species and probable alteration of the electron energy distribution function (due to EIE ionization and collisional dissociation of molecules) appear to be the major sources of interference. Classical analyte molecule formation, gas-phase expulsion and de-tuning of the plasma in the presence of large masses of EIE are not significant factors in determining the extent of interference.

Spatial imaging of the furnace atomization plasma emission spectrometry source

The spatial distribution of background species and analyte in a He FAPES source have been determined using a charge-coupled device (CCD) imaging system. Imaging of the He 667.82 nm support gas line reveals the presence of two distinct plasmas: an intense luminous zone located around the centre electrode and a diffuse plasma near the tube walls. In a graphite tube at room temperature, the plasma system exhibits a significant dependence on the d.c. bias of the centre electrode for a constant forward r.f. power of 50 W. Polyatomic background species exhibit similar overall distributions and response to changes in the centre electrode d.c. bias. The ingress of atmospheric nitrogen into the plasma can be indirectly detected at elevated tube wall temperatures. Images obtained for Ag atomized into 30 W and 50 W plasmas point out the role of the centre electrode as a primary condensation and secondary re-volatilization site. Condensation and re-evaporation is alleviated when Ag is atomized into a 70 W plasma as the result of plasma-induced heating of the centre electrode.

Furnace atomization plasma emission spectrometry at controlled pressures

A furnace atomization plasma emission source was operated in a controlled pressure He environment (200–2000 Torr)(1 Torr = 133.322 Pa). The response from several elements (Cd, Pb, Ag, Mn, Cu, Fe and Co) as well as emission from He l at 388.8 nm and the temperature of the centre electrode (CE) were measured. Below 800 Torr the temperature of the CE increases with increasing pressure, as does emission from the analytes and He l. This can be attributed to increases in the gas density and collision frequency. Response reached an optimum slightly above atmospheric pressure and declined thereafter. At high pressures (>1200 Torr), the emission from Cd, Pb and Ag again increased, probably as a result of an increase in the efficiency of deposition of these analytes onto a cooler CE (secondary site). The effect of pressure on detection limit and linear range of calibration for Cd and Mn was also examined.

Impact of bias voltage on furnace atomization plasma emission spectrometry performance

The effects of an applied d.c. bias potential on the analytical response from a furnace atomization plasma emission spectrometry (FAPES) source operating with a 50 W He plasma were investigated. Enhancements in absolute sensitivity and detection limits for B, Cd, Pb, Ni, Fe, S, Pt and Se ranged from 2–10-fold as compared to the usual “free running” self-bias situation and response from all species was enhanced as the applied bias was made more negative. Reflected power increases up to 35 W exert little effect on the excitation conditions within the plasma. The excitation temperature of the He support gas as well as that of Fe introduced as a thermometric species indicated that, while the temperature of the former varied by up to 700 K over the course of an atomization transient, that of Fe remained relatively stable. Bias control reduced the fluctuation in the He temperature to under 400 K.

Figures of merit for two-step furnace atomization plasma emission spectrometry

A furnace atomization plasma emission spectrometry (FAPES) system was assembled using a two-step graphite furnace which consisted of a spatially isothermal tube positioned at the top of a cup. It was possible to ignite and stabilize an He 50 W r.f. plasma, tuned for a reflected power of less than 5 W, inside the tube, at temperatures of 2500–2600 K and subsequently heat the cup to vaporize the sample. Detection limits for Cr and Al were 298 and 30 pg, respectively. Sensitivities and detection limits for Pb, Cd and Sn were comparable to previously published values using a Massmann-type FAPES system employing a platform and Pd modifier.

Developments and trends in plasma spectrochemistry—a view. Plenary lecture

A review of the history of spectrochemistry over the past 40 years is taken as a starting-point for presenting a personal view on recent developments and current trends in plasma spectrochemistry. Booms and trends, featured in graphical form, are introductorily discussed. In that context, an iconographic approach for the visualization of ratings of analysis methods is proposed. The main body of the discussion deals with assessments of the present position and future perspectives of furnace atomization plasma emission spectrometry, plasma source mass spectrometry, plasma source emission spectrometry, and, as a perhaps curious intruder and possibly serious competitor, total-reflection X-ray fluorescence spectrometry. The potentials of recently introduced echelle array spectrometers for plasma source emission spectrometry are considered in the light of new or improved insights into the spectroscopic methodology and in the scope of input from developments in chemometrics. The paper is concluded with a brief review of the plasma spectrochemistry conferences in the past 18 years and their role for communication.

Excitation and detection of molecular species with furnace atomization plasma emission spectrometry

Detection of molecular emission from analyte species introduced into the source of a furnace atomization plasma emission spectrometer is demonstrated for the monochlorides of lead, cadmium, zinc and tellurium and the monoxides of lead and phosphorus. Reduced palladium is shown to be effective in eliminating these species.

Influence of the Generator Frequency on the Analytical Characteristics of FAPES

A preliminary study of the influence of generator frequency on the operating and analytical characteristics of atmospheric-pressure rf He and Ar plasmas in a FAPES (Furnace Atomization Plasma Emission Spectrometry) system is presented. Apparent forward powers of 50 W were used to establish He plasmas at 13.6,27,40, and 54 MHz and Ar plasmas at 27 and 40 MHz. He and Ar excitation temperatures were of comparable magnitude (∼3400 K) and exhibited a monotonic increase with operating frequency. Both plasmas produced complex background structure due to excitation of molecular impurities. Significant was the presence of carbon-containing molecules (CN, C2) in the Ar plasma as a result of its enhanced sputtering capabilities. Analyte sensitivity increased with frequency, but detection limits were frequency independent. Sensitivities (peak height and area) for Ag, Cu, Mn, Pb, Ni, and Fe were consistently greater in the Ar plasma.

Application of platform and palladium modification techniques with furnace atomization plasma emission spectrometry

Figures of merit (limit of detection, sensitivity and precision) for eight elements (Ag, Cd, Pb, Mn, Sn, Tl, As and Se) were obtained using furnace atomization plasma emission spectrometry (FAPES) in combination with atomization of samples from a L'vov platform and the use of a Pd modifier (0.5 µg). A 50 W He plasma was utilized. Precision of replicate integrated signals averaged 2.8%(range 1.7–4.3%) for injection, by hand, of samples at concentrations 13–70-fold above the detection limit. Estimated limits of detection and sensitivities for integrated intensities improved 3–10- and 6–17-fold, respectively, for volatile elements (Cd, Pb and Ag) compared with sample atomization from the tube wall. Added NaCl, up to 24 µg, had no effect on the recovery of the integrated signal from Pb when a 100 W plasma was used.

Characteristic temperatures in a FAPES source

A number of state distribution temperatures were measured in an effort to characterize a 100 W 13.56 MHz rf He plasma established in a FAPES (Furnace Atomization Plasma Emission Spectrometry) source. Excitation temperatures derived from a Boltzmann plot of He I and Fe I lines were in reasonable agreement, i.e. 3300 ± 180 and 2920 ± 180 K, respectively. An excitation temperature measured with Fe II lines was substantially larger than the above values, being 7610 ± 450 K. A kinetic or Doppler temperature based on measurement of the width of the Be I 234.861 nm line profile was 7030 ± 1150 K whereas the He ionization temperature derived from the measured electron number density was 10920 ± 1900 K. It is clear that complete LTE does not exist in this source

Tandem sources using electrothermal atomizers: analytical capabilities and limitations

Tandem emission sources with electrothermal volatilization and atomization of the sample, such as furnace atomic non-thermal excitation spectrometry (FANES) or furnace atomization plasma emission spectrometry, are compared with other excitation sources, e.g., an inductively coupled plasma. The interdependence between the excitation and atomization processes, which causes restrictions for analytical procedures, is considered. Of particular interest for the analytical applications of tandem sources is the influence of matrix constituents on the excitation conditions. Furnace atomizers are able to form relatively high matrix concentrations in the excitation plasma, which can lead to a breakdown of the initial electron energy distribution. Correspondingly, depression of the analytical signals by the matrix has been found for FANES, which leads to some general conclusions on tandem sources.

Figures of merit for furnace atomization plasma emission spectrometry

Analytical figures of merit for nine elements (viz. Ag, Cd, Pb, Ni, Be, Fe, Bi, Cu, and P) are presented that serve to broadly characterize the furnace atomization plasma emission spectrometry technique. Detection power lies in the low picogram region; precision of replicate signals obtained with injection of samples by hand ranges from 2.2 to 12.1% relative standard deviation and the linear range of calibration spans 2-4 orders of magnitude. Relative sensitivities of alternative atom and ion lines are given for each element. Sufficient energy is available to efficiently detect analyte ion lines having excitation energies of up to 13 eV. Static and dynamic background spectra are presented which reveal broad-band contributions from molecular species such as CO, N{sub 2}, NO, and OH as well as atom lines from the He support gas.