Determination of trace impurities in high purity copper using sector-field ICP-MS: continuous nebulization, flow injection analysis and laser ablation

High resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was applied for multielement-determination in high-purity copper (approx. 99.99%). The samples were introduced into the instrument by three different introduction systems, which were studied with respect to high accuracy, low detection limits and fast analysis: continuous nebulization (CN), flow injection analysis (FIA) and laser ablation (LA). The trueness of the applied method was checked by the analysis of high-purity copper reference material (BCR Cu074). All values obtained for this CRM using CN were in the range of the stated uncertainty for the 9 elements determined: Ag, As, Bi, Cr, Fe, Ni, Pb, Sb, and Sn with contents in the range of 0.5–13 μg/g. Another approach for checking the trueness of the method was to compare the results obtained by this method characterizing the purity of a 4N (99.99% copper content) copper material with those obtained by application of electrothermal atomic absorption spectrometry (ET-AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES). For further characterizing, the concentrations of 49 elements were found in this material below detection limits of HR-ICP-MS in the range of low μg/kg and sub μg/kg. The combination of HR-ICP-MS and a flow injection analysis system (FIAS) improved the robustness of the system in regard to high matrix concentrations. Therefore, matrix concentrations up to 4 g/L could be used for liquid analysis and detection limits were lowered by a factor of 2–5. A calibration method for bulk analysis with laser ablation was developed with doped copper powder as pressed pellets for calibration standards. This method proved to be an excellent fast semi-quantitative method, which was less time consuming in comparison with the analysis of liquids. After application of correction factors the deviation between the results obtained by laser ablation and by analysis of liquids was ≈ 15% for most elements. The method offered the possibility to check for potential losses of analytes occurring during the wet chemical operations. Received: 23 November 1998 / Revised: 25 February 1999 / Accepted: 2 March 1999     

Trace analysis of high-purity graphite by LA–ICP–MS

Laser-ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) has been established as a very efficient and sensitive technique for the direct analysis of solids. In this work the capability of LA–ICP–MS was investigated for determination of trace elements in high-purity graphite. Synthetic laboratory standards with a graphite matrix were prepared for the purpose of quantifying the analytical results. Doped trace elements, concentration 0.5 μg g^–1, in a laboratory standard were determined with an accuracy of 1% to ± 7% and a relative standard deviation (RSD) of 2–13%. Solution-based calibration was also used for quantitative analysis of high-purity graphite. It was found that such calibration led to analytical results for trace-element determination in graphite with accuracy similar to that obtained by use of synthetic laboratory standards for quantification of analytical results. Results from quantitative determination of trace impurities in a real reactor-graphite sample, using both quantification approaches, were in good agreement. Detection limits for all elements of interest were determined in the low ng g^–1 concentration range. Improvement of detection limits by a factor of 10 was achieved for analyses of high-purity graphite with LA–ICP–MS under wet plasma conditions, because the lower background signal and increased element sensitivity. Received: 4 January 2001 / Revised: 27 March 2001 / Accepted: 28 March 2001     

Determination of trace amounts of gold and silver in high-purity iron and steel by electrothermal atomic absorption spectrometry after reductive coprecipitation

Trace amounts of gold and silver in high-purity iron or steel were preconcentrated by reductive coprecipitation with palladium using ascorbic acid, and determined by electrothermal atomic absorption spectrometry (ET-AAS). Both gold and silver could be simultaneously separated and sensitively determined in 10 metals (aluminum, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, vanadium and zinc). Comparable values were obtained for gold and silver in reference materials (low alloy steel) by the proposed method and a non-separation method; good agreement was found between the analytical values by both methods and the certified values. The proposed method is easy, simple and not dependent on sample composition and content. Moreover, gold and silver in metal samples could be simultaneously separated together with selenium and tellurium. The detection limits for gold and silver (3 σ) are 0.003 μg g^–1 and 0.002 μg g^–1, respectively. Received: 3 February 2000 / Revised: 11 April 2000 / Accepted: 16 April 2000     

Determination of trace amounts of gold and silver in high-purity iron and steel by electrothermal atomic absorption spectrometry after reductive coprecipitation

Trace amounts of gold and silver in high-purity iron or steel were preconcentrated by reductive coprecipitation with palladium using ascorbic acid, and determined by electrothermal atomic absorption spectrometry (ET-AAS). Both gold and silver could be simultaneously separated and sensitively determined in 10 metals (aluminum, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, vanadium and zinc). Comparable values were obtained for gold and silver in reference materials (low alloy steel) by the proposed method and a non-separation method; good agreement was found between the analytical values by both methods and the certified values. The proposed method is easy, simple and not dependent on sample composition and content. Moreover, gold and silver in metal samples could be simultaneously separated together with selenium and tellurium. The detection limits for gold and silver (3 σ) are 0.003 μg g^–1 and 0.002 μg g^–1, respectively. Received: 3 February 2000 / Revised: 11 April 2000 / Accepted: 16 April 2000     

Determination of trace elements in zeolites by laser ablation ICP-MS

Laser ablation inductively coupled plasma mass spectrometry using a quadrupole-based mass spectrometer (LA-ICP-QMS) was applied for the analysis of powdered zeolites (microporous aluminosilicates) used for clean-up procedures. For the quantitative determination of trace element concentrations three geological reference materials, granite NIM-G, lujavrite NIM-L and syenite NIM-S, from the National Institute for Metallurgy (South Africa) with a matrix composition corresponding to the zeolites were employed. Both the zeolites and reference materials were fused with a lithium borate mixture to increase the homogeneity and to eliminate mineralogical effects. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS relative sensitivity coefficients (RSCs) of chemical elements and calibration curves were measured using the geostandards. The experimentally obtained RSCs are in the range of 0.2-6 for all elements of interest. Calibration curves for trace elements were measured without and with Li or Ti as internal standard element. With a few exceptions the regression coefficients of the calibration curves are better than 0.993 with internal standardization. NIM-G granite reference material was employed to evaluate the accuracy of the technique. Therefore, the measured concentrations were corrected with RSCs which were determined using lujavrite reference material NIM-L. This quantification method provided analytical results with deviations of 1–11% from the recommended and proposed values in granite reference material NIM-G, except for Co, Cs, La and Tb. The relative standard deviation (RSD) of the determination of the trace element concentration (n = 5) is about 1% to 6% using Ti as internal standard element. Detection limits of LA-ICP-QMS in the lower μg/g range (from 0.03 μg/g for Lu, Ta and Th to 7.3 μg/g for Cu, with the exception of La) have been achieved for all elements of interest. Under the laser ablation conditions employed (λ: 266 nm, repetition frequency: 10 Hz, pulse energy: 10 mJ, laser power density: 6 × 10⁹ W/cm²) fractionation effects of the determined elements relative to the internal standard element Ti were not observed. Received: 7 April 2000 / Revised: 25 May 2000 / Accepted: 31 May 2000     

Elemental mapping and quantitative analysis of Cu, Zn, and Fe in rat brain sections by laser ablation ICP-MS

This report details the application of laser ablation quadrupole ICP-MS for the (multi)elemental mapping of 100-μm-thick sections of rat brain. The laser spot size used was 60 μm, and the laser scan speed was 120 μm s⁻¹. The analysis was relatively rapid, allowing mapping of a whole brain thin section (≈1 cm²) in about 2 h. Furthermore, the method was amenable to multi-element data collection including the physiologically important elements P and S and afforded sub μg g⁻¹ detection limits for the important trace elements Cu and Zn. Calibrations were performed with pressed pellets of biological certified reference materials, and the elemental distributions and concentrations of Cu, Zn, and Fe were determined in whole rat brain sections. The distributions and concentration ranges for these elements were consistent with previous studies and demonstrate the utility of this technique for rapid mapping of brain thin sections.     

Optimization of a laser ablation-inductively coupled plasma “time of flight” mass spectrometry system for short transient signal acquisition

Simultaneous ion sampling and sequential detection offered by inductively coupled plasma ‘time of flight’ mass spectrometry (ICP-TOFMS) provides advantages for the analysis of short transient concentration-variable signals as produced in laser ablation. In order to investigate the capabilities of ICP-TOFMS in combination with an excimer laser ablation system, ablation studies on reference materials and geological samples were carried out. Various ICP-TOFMS parameters were optimized for laser-induced aerosols. Transverse rejection ion pulse was used to extend the dynamic range in concentration. A reduced volume ablation cell was designed and used in order to increase the sample density in the ICP. Results for 63 simultaneously measured isotopes (SRM 610 from NIST) lead to limits of detection in the 1–100 μg/g range for a 80 μm crater diameter (10 Hz, 1.2 mJ pulse energy). The reproducibility of signal ratios was determined to be better than 2% RSD for transient signals using 102 ms integration time. These optimized parameters were then used for the analysis of tin-rich fluid inclusions. Preliminary results of multielement analysis and isotopic ratio determinations on individual fluid inclusions (63 isotopes, 102 ms integration time) demonstrate the capabilities of ICP-TOFMS in combination with laser ablation. Received: 6 March 2000 / Revised: 11 May 2000 / Accepted: 14 May 2000     

Bromide/bromate speciation by NTI-IDMS and ICP-MS coupled with ion exchange chromatography

 Two different mass spectrometric methods, negative thermal ionization isotope dilution mass spectrometry (NTI-IDMS) and inductively coupled plasma mass spectrometry (ICP-MS), off-line and on-line coupled with anion exchange chromatography, have been developed for simultaneous bromide and bromate determinations in water samples. The detection limits of these methods are in the range of 0.03–0.09 μg/L using a 50 mL sample.The results are independent of the content of other anions, which could be demonstrated by the analyses of six mineral waters containing chloride and sulfate of up to 160 mg/L and 1500 mg/L, respectively. Bromide has been analyzed by the NTI-IDMS method in the range of 10–500 μg/L and bromate in the range of 1–50 μg/L with relative standard deviations of 0.3–1.2% and 0.4–6%. Quantification for the ICP-MS method was carried out by the standard addition technique, which resulted in relative standard deviations of 5.5% for bromide at the 500 μg/L level and of 13% for bromate at the level of about 3 μg/L. These results are compared with those described in the literature for ion chromatographic (IC) and other methods and those obtained in this work by IC using UV detection, which allows high concentrations of chloride in the bromate fraction. The detection limits of this IC method are 6 μg/L for bromide and 30 μg/L for bromate. NTI-IDMS and ICP-MS therefore fit the recommendations of the European Union (detection limit<2.5 μg/L; precision and accuracy better than 25% at the 10 μg/L level) for methods analyzing the carcinogenic bromate much better than IC and other methods applied up to now. As a definitive but time consuming method, NTI-IDMS is preferably applicable as a calibration technique, whereas ICP-MS, with relatively short analysis times, due to on-line coupling with chromatography, can be used as a sensitive and powerful routine method for trace bromide and bromate species in water samples. Received: 5 July 1996/Accepted: 7 August 1996     

Bromide/bromate speciation by NTI-IDMS and ICP-MS coupled with ion exchange chromatography

 Two different mass spectrometric methods, negative thermal ionization isotope dilution mass spectrometry (NTI-IDMS) and inductively coupled plasma mass spectrometry (ICP-MS), off-line and on-line coupled with anion exchange chromatography, have been developed for simultaneous bromide and bromate determinations in water samples. The detection limits of these methods are in the range of 0.03–0.09 μg/L using a 50 mL sample.The results are independent of the content of other anions, which could be demonstrated by the analyses of six mineral waters containing chloride and sulfate of up to 160 mg/L and 1500 mg/L, respectively. Bromide has been analyzed by the NTI-IDMS method in the range of 10–500 μg/L and bromate in the range of 1–50 μg/L with relative standard deviations of 0.3–1.2% and 0.4–6%. Quantification for the ICP-MS method was carried out by the standard addition technique, which resulted in relative standard deviations of 5.5% for bromide at the 500 μg/L level and of 13% for bromate at the level of about 3 μg/L. These results are compared with those described in the literature for ion chromatographic (IC) and other methods and those obtained in this work by IC using UV detection, which allows high concentrations of chloride in the bromate fraction. The detection limits of this IC method are 6 μg/L for bromide and 30 μg/L for bromate. NTI-IDMS and ICP-MS therefore fit the recommendations of the European Union (detection limit<2.5 μg/L; precision and accuracy better than 25% at the 10 μg/L level) for methods analyzing the carcinogenic bromate much better than IC and other methods applied up to now. As a definitive but time consuming method, NTI-IDMS is preferably applicable as a calibration technique, whereas ICP-MS, with relatively short analysis times, due to on-line coupling with chromatography, can be used as a sensitive and powerful routine method for trace bromide and bromate species in water samples. Received: 5 July 1996/Accepted: 7 August 1996     

Simultaneous Voltammetric Determination of Molybdenum and Copper in Manganese Compounds

 Adsorptive voltammetry was employed for the determination of copper and molybdenum in manganese compounds. As working electrode the hanging mercury drop electrode (HMDE) was used. The method was applied in aqueous solutions of MnCl₂ and Mn(NO₃)₂, as well as in pre-treated manganese dioxide and manganese ores. The detection limits are 3 μg/g for copper and 5 μg/g for molybdenum in the sample. The RSDs at concentration level of 8 μg/g are 2.2 and 3.2% for copper and molybdenum, respectively.     

State-of-the-art contamination control techniques for ultratrace elemental analysis

The detection limits of many nonnuclear methods for ultratrace (≤0.1 μg/g) elemental determinations lie well below the level at which precise and accurate practical analysis can be executed routinely. Advances in analytical methodologies which are rapidly eroding such disparities are reviewed. The applications of X-ray fluorescence, atomic absorption, stable isotope dilution mass spectrometry, and laser intracavity absorption spectrophotometry to ultratrace analyses not amenable to solution by nuclear methods are discussed.     

Determination of trace elements in residual oil by high-resolution inductively coupled plasma mass spectrometry

An analytical method using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of 20 elements, including Na, Mg, Al, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, and Pb elements, in residual oil was described. The sample was dissolved in HNO₃ by microwave digestion, and then the above 20 elements in the solution were analyzed directly by HR-ICP-MS. Most of the spectral interferences could be avoided by measuring in the high-resolution mode. The matrix effect caused by the sample-digesting solution and corrected by Sc, Rh, and Bi as the internal standard elements was studied in detail. The optimum condition of the determination was also tested and discussed. The result showed that the detection limits of the method were in the range of 0.014 to 11.6 μg L⁻¹; the relative standard deviation was less than 3.8% and recoveries in the samples were in the range of 88.4% to 108.0%. This method can be used to determine the trace elements in residual oil with the features of accurate, rapid, and convenient determination.     

Application of a double-focusing magnetic sector inductively coupled plasma mass spectrometer with laser ablation for the bulk analysis of rare earth elements in rocks fused with Li2B4O7

Results of the use of a double-focusing, magnetic sector inductively coupled plasma mass spectrometer (ICP-MS) with ultraviolet (UV) laser ablation (LA) are presented for the bulk analysis of rare earth elements (REEs) in rocks fused with Li₂B₄O₇. The sample preparation procedure used a sample to flux weight ratio of 1 : 7, and was identical with a procedure routinely used for X-ray fluorescence (XRF) analyses of major and minor elements in geological materials. Calibration was based on a total of 18 international standard reference materials (SRMs), and Ba was used as an internal standard element for all REEs. The calibration curves were constructed using a weighted regression model. The use of internal standard, without exception, improved the correlation coefficients significantly. The 3σ detection limits were established by a blank sample of SiO₂ spiked with Ba, and were in the range from 0.003 μg g^–1 (¹⁵⁹Tb) to 0.051 μg g^–1 (¹⁴⁰Ce). The use of a large set of SRMs for calibration gave a good basis for the evaluation of analytical quality, and extensive data for calculated analytical uncertainty are presented. Instrumental precision and the repeatability of the method were studied separately, and no significant difference in these two sets of parameters were found, indicating that the spread of results predominantly was connected to the instrumental measurements. Repeated ablations on the surface of a disk did not influence subsequent measurements with XRF, showing that the fused disks can be stored for future use in XRF and/or LA-ICP-MS analysis. Received: 12 February 1998 / Revised: 6 April 1998 / Accepted: 17 April 1998     

The non-destructive determination of REE in fossilized bone using synchrotron radiation induced K-line X-ray microfluorescence analysis

The sensitivity and applicability of the synchrotron radiation induced X-ray microfluorescence (μ-SRXRF) spectrometer at the Hamburg synchrotron laboratory Hasylab for the determination of the distribution of trace concentrations of rare-earth elements (REE) in fossilized bone are discussed and critically compared to those of other trace analytical methods such as instrumental neutron activation analysis (INAA) and LAMP-ICPMS (laser ablation microprobe inductively-coupled plasma mass spectrometry). Measurements were carried out on two bone samples from contrasting terrestrial depositional environments at Olduvai Gorge (Tanzania). Results indicate that the microdistribution of the REE in these biological materials is not homogeneous and that the relative abundance of these elements can provide information on the palaeoenvironment during the fossilization process. The heterogeneous distribution of the REE can be determined in a quantitative and completely non-destructive manner provided the concentrations of individual REE are above 10 μg/g. Received: 18 January 1998 / Revised: 6 October 1998 / Accepted: 10 October 1998     

Laser ablation-atomic fluorescence approach for the determination of mercury

A method for the determination of mercury in solid samples using laser ablation coupled with atomic fluorescence spectroscopy has been developed. An Nd-YAG laser was used for ablation and the vaporised and atomised material was rapidly led to an atomic fluorescence detector, where excitation and emission took place. The experimental approach was applied to the assessment of different procedures as sensitive as possible for implementing standard addition methods. Calibration curves were recorded using the prepared standards, which exhibited linear ranges between 0.5–100 μg/g, with excellent regression coefficients in all instances (0.9907). The precision, expressed as RSD %, was 3 and 4% for contents of 1 and 30 μg/g, respectively, in the same pellet; and 7 and 12% for the same contents and different type of pellets. The method has been applied to the determination of mercury in CRM of sewage sediment and a sludge sample with a known amount of mercury determined by an interlaboratory study. The results obtained show good agreement with those expected. Received: 21 December 1998 / Revised: 12 April 1999 / Accepted: 14 April 1999     

Determination of Cu, Zn and Cd in water by FAAS after preconcentration by baker’s yeast (Saccharomyces cerevisiae) immobilized on sepiolite

By using the adsorbent Saccharomyces cerevisiae immobilized on sepiolite an adsorption-elution method was developed for the preconcentration of Cu, Zn, and Cd followed by flame atomic absorption spectrometry (FAAS). Recoveries were 98.3 ± 0.4% for Cu, 94.2 ± 0.3% for Zn, and 99.04 ± 0.04% for Cd at 95% confidence level obtained by the column method. The influence of sea water matrix elements on the separation of the trace elements was also assessed by using the column procedure. The breakthrough capacities were found to be 74 μmol/g for copper, 128 μmol/g for zinc and 97 μmol/g for cadmium. After optimization the proposed method was applied to the trace metal determination in sea and river water. Received: 8 June 1998 / Revised: 8 September 1998 / Accepted: 16 September 1998     

The application of butanol as dilution agent for the inductively coupled plasma-atomic emission spectrometric determination of boron and phosphorus in lubricating oils

An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5% for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil. Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997     

Determination of 2-isopropyl thioxanthone and 2-ethylhexyl-4-dimethylaminobenzoate in milk: comparison of gas and liquid chromatography with mass spectrometry

Liquid chromatography–tandem mass spectrometry (LC-MS/MS) and gas chromatography–mass spectrometry (GC-MS) have been compared for the analysis of 2-isopropyl thioxanthone (ITX) and 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB). Pressurized liquid extraction (PLE) was applied for the extraction of ITX and EHDAB from milk and milk-based beverages. Samples were homogenized with sea sand and anhydrous sodium sulfate, and were extracted with ethyl acetate at 100 °C and 10.3 × 10⁶ Pa in one cycle of 10 min at 90% flush. Both, GC-MS and LC-MS/MS were suitable to determine these photoinitiators in the PLE extracts, providing appropriate identification and quantification. The recoveries obtained ranged from 70 to 99% for ITX and from 70 to 95% for EHDAB. These recoveries were equal as those obtained by a conventional liquid–liquid partitioning with acetonitrile and tert-butyl methyl ether–hexane. The quantification limits using GC-MS, based on a signal-to-noise ratio of 10, were 0.5 μg/L for ITX and 1 μg/L for EHDAB. The repeatability of the method, as indicated by the relative standard deviations, was within the range 0.9–16.1%. The same parameters calculated using LC-MS/MS result in quantification limits of 0.1 μg/L for ITX and 0.02 μg/L for EHDAB and repeatability within the range 5.2–19.4%. These results pointed out that both techniques are appropriate to determine these compounds in food samples. The method was applied to milk and milk-based beverages from different supermarkets. The ITX and EHDAB contents ranged from 2.5 to 325 μg/L and from 8 to 126 μg/L, respectively. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The application of butanol as dilution agent for the inductively coupled plasma-atomic emission spectrometric determination of boron and phosphorus in lubricating oils

An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5% for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil. Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997     

Elemental composition of drinking water supplies in three states in Southeastern Nigeria

The levels of some trace elements; Co, Mn, Cu, Zn, Cr, Cd, Pb, Fe, Hg, Se, As, Ni and minor elements; Na, K, Ca and Mg were determined in public drinking water supplies (public taps and groundwaters) in three states in Southeastern Nigeria using energy dispersive X-ray fluorescence spectrometry (EDXRF) and flame atomic absorption spectrometry (FAAS). The mean levels of most of the trace elements in the groundwater samples were below the World Health Organization (WHO) drinking water quality limits, the only exception being Hg whose mean value of 3.69 μg/l exceeded the WHO limit of 1.0 μg/l. Violations of the WHO limits were also observed for Fe, Zn, Se and Pb in some of the groundwater samples. In the public tap samples only Hg violated the WHO limit.