Determination of cadmium, lead and copper in water samples by flame atomic-absorption spectrometry with preconcentration by flow-injection on-line sorbent extraction

Cadmium, lead and copper were determined in synthetic sea-water, drinking water and the NBS 1643b Trace Elements in Water standard reference material at mug/l. levels by flame atomic-absorption spectrometry after on-line preconcentration by sorbent extraction with a flow-injection system. Bonded silica with octadecyl functional groups packed in a micro column of 100 mul capacity was used to collect diethylammonium diethyldithiocarbamate complexes of the heavy metals in the aqueous samples. The sample loading time was 20 sec at a flow-rate of 3.3 ml/min. Ethanol or methanol was used to elute the adsorbed analytes into the spectrometer. The sample loading rate, elution rate and pH were optimized. Enrichment factors of 19-25 for Cd, Pb and Cu were achieved at sampling frequencies of 120/hr with precisions of 1.4, 1.0 and 1.3% rsd (n = 11), respectively. The detection limits (3sigma) for Cd, Pb and Cu were 0.3, 3 and 0.2 mug/l., respectively. Determination of Cd, Pb and Cu in NBS SRM 1643b showed good agreement with the certified values. Recoveries of Cd and Pb added to sea-water were 95 and 102%, respectively.     

Determination of Ba, Cd, Cu, Pb and Zn in saliva by isotope dilution direct injection inductively coupled plasma mass spectrometry

Trace elements in small sample volumes of saliva were determined by coupling a high efficiency direct injection nebulizer to inductively coupled plasma mass spectrometry and employing quantification by isotope dilution. Aliquots of 0.4 ml of human saliva were mixed with 0.1 ml of concentrated nitric acid and diluted to 2 ml with water. Sample solutions were spiked with an isotopic solution enriched in 135Ba, 112Cd, 65Cu, 206Pb and 66Zn. The amount of each isotope added to the samples and the measurement procedure were adjusted to attain precise analytical results calculated from the isotope ratios 135Ba/138Ba, 112Cd/114Cd, 65Cu/63Cu, 206Pb/208Pb and 66Zn/68Zn. Data acquisition for Ba, Cu and Zn isotopes was performed for a single sample injection of 50 microl and in another sample injection the Cd and Pb isotopes were measured. Concentrations ranging from 5.0 to 16 microg l(-1) for Ba, from 0.50 to 1.1 microg l(-1) for Cd, from 6.0 to 50 microg l(-1) for Cu, from 0.8 to 18.8 microg l(-1) for Pb and from 46.0 to 230 microg l(-1) for Zn were found in saliva samples. Detection limits of 0.11, 0.03, 0.40, 0.05 and 0.59 microg l(-1) were determined for Ba, Cd, Cu, Pb and Zn, respectively. The concentrations found by isotope dilution were in agreement with those of the completely digested samples quantified by external calibration. The direct analysis of 30 samples per hour was attained with the proposed procedure, avoiding time-consuming digestion steps, contamination risks and matrix effects.     

Electrothermal atomization atomic absorption spectrometric determination of trace metals in uranium-plutonium fuel materials

Summary Atomic absorption spectrometric methods using the electrothermal mode of atomization developed for the determination of Ag, Be, Ca, Cd, Cr, Co,Cu, Fe, Li, Mn, Na, Ni, Sn and Zn in (U, Pu) solution with 4% plutonium have been described. The carbon rod atomizer has been adapted for glove box operation to enable handling of plutonium containing solution samples. Multielement solution standards with graded concentrations of the analytes and fixed concentration of the matrix are used in the standardization process. Nanogram to sub-nanogram quantities of the analytes have been determined with a precision of better than 9% RSD using 5 l of the sample aliquots.

---

Bestimmung von Metallspuren in Uran-Plutonium-Kernbrennstoffen mit Hilfe der ETA-AAS

     

Elimination of matrix effect and simultaneous determination of multi-components in complex systems by matrix coefficient non-linearity multivariate calibration based on single point response signals.

In order to deal with the matrix effect in the simultaneous determination of multi-components in a complex system, we have developed a novel method named matrix coefficient multivariate calibration method (MCMCM) for simultaneously determining n analytes in complex systems. The calibration models of n analytes, which are based on the experimental data of known samples, are first transformed into n linear equations, and then the equations are solved to obtain matrix calibration coefficients of the analytes in congeneric samples. In this way, the concentrations of n analytes in the unknown sample could be obtained easily and simultaneously by solving another n-variate linear equations with the help of the matrix calibration coefficients obtained-above. The method proposed in this work has been tested by voltammetry and atomic absorption spectrometry (AAS) with satisfactory results. On determining the elements such as Cu, Pb, Cd, Ni, Zn, Fe, Mn, Co, Ca, Mg, etc. in synthetic samples, the relative standard deviations (RSDs) of the results were 0.91 - 4.5%, and the recoveries were 95.8 - 105%. For actual samples, the RSDs and the recoveries were 1.5 - 6.9 and 92.0 - 110%, respectively.     

Preconcentration and separation with Amberlite XAD-4 resin; determination of Cu, Fe, Pb, Ni, Cd and Bi at trace levels in waste water samples by flame atomic absorption spectrometry

A method for the preconcentration of Cu, Fe, Pb, Ni, Cd and Bi as their diethyldithiocarbamate chelates was proposed using a column filled with Amberlite XAD-4 resin. The retained analytes on the resin were recovered with a small volume of acetone. The metal ions in the effluent were determined by a flame atomic absorption spectrometer. Different factors including pH of sample solution, sample volume, amount of XAD-4 resin, amount of ligand, eluent volume and matrix effects for preconcentration were examined. The recoveries for the analytes under the optimum working conditions were higher than 95%. The relative standard deviations of the determinations were below 9%. The limits of detection (3 s, n=20) for analytes were found to be between 4 and 23 mug l(-1). The proposed method was applied to the analysis of some waste waters from the organized industrial region of Kayseri.     

Direct determination of cadmium and copper in seawater using a transversely heated graphite furnace atomic absorption spectrometer with Zeeman-effect background corrector

Methods for the direct determination of copper and cadmium in seawater were described using a graphite furnace atomic absorption spectrometer (GFAAS) equipped with a transversely heated graphite atomizer (THGA) and a longitudinal Zeeman effect background corrector. Ammonium nitrate was used as the chemical modifier to determine copper. The mixture of di-ammonium hydrogen phosphate and ammonium nitrate was used as the chemical modifier to determine cadmium. The matrix interference was removed completely so that a simple calibration curve method could be applied. This work is the first one with the capability of determining cadmium in unpolluted seawater directly with GFAAS using calibration curve based on simple aqueous standards. The accuracy of the methods was confirmed by analysis of three kinds of certified reference saline waters. The detection limits (LODs), with injection of a 20-mul aliquot of seawater sample, were 0.06 mug l(-1) for copper and 0.005 mug l(-1) for cadmium.     

Column-switching high-performance liquid chromatographic analysis of carbamazepine and its principal metabolite in human plasma with direct sample injection using an alkyl-diol silica (ADS) precolumn

In this paper, the on-line coupling of solid-phase extraction, based on a restricted-access support with high-performance reverse phase chromatography for the analysis of carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-E) in human plasma samples is described. A precolumn packed with 25 mum C(18) alkyl-diol support is used for direct plasma injection. Using column-switching techniques, the analytes were enriched on the precolumn by a 5 mM phosphate buffer (pH 7) with 2% of methanol solution at a flow-rate of 0.8 ml min(-1), while proteins and endogenous hydrophilic substances in plasma were washed off to waste. The enriched analytes were then back-flushed onto the analytical C(18) column, separated by a mixture of 10 mM phosphate buffer (pH 7) acetonitrile (70:30 v/v) solution at a flow-rate of 1.0 ml min(-1) and detected by the ultraviolet absorbance set at 212 and 285 nm and without transfer loss. Linear calibration graphs were obtained for sample injection volumes of 50 (0.2-4.0 of mug of CBZ ml(-1) and 0.1-5.0 mug of CBZ-E ml(-1), respectively), and 20 mul (5.0-20.0 mug of CBZ ml(-1)); in either case the r-value was >0.9963. Recoveries from spiked plasma samples were quantitative for both analytes and the coefficients of variation were below 3.83%. The lowest samples concentrations that can be quantified with acceptable accuracy and precision was 0.2 mug CBZ ml(-1) and 0.1 mug CBZ-E ml(-1) when a sample volume of 50 mul was injected. Concentrations of 0.08 and 0.05 mug ml(-1) of CBZ and CBZ-E were considered the limit of detection for a signal-to-noise ratio of 3. Furthermore, the developed column-switching method was successfully applied to the determination of CBZ and CBZ-E in plasma samples of patients submitted to CBZ therapy.     

Determination of Cd in sonicate slurries and leachates of biological and environmental materials by FI-CV-AAS

An analytical method for Cd analysis in solid samples which combines the ultrasonic slurry formation with cold vapour generation and atomic absorption spectrometry is described. The samples are suspended in HCl and sonicated until homogeneous and reduced particle size slurry formation. Several aspects were studied: acidity of the medium, sonication time, and slurry formation in different matrices. The procedure described permits the use of direct calibration, with KCN addition as masking agent of interfering ions (Cu, Pb, Ni and Zn) present in the environmental matrices. Supernatant analysis of these last samples experimentally shown that preparation of the suspension with 6 mol l(-1) HCl concentration led to quantitative extraction of Cd. Biological materials analysis needed the use of the standard addition calibration method due to the high matrix effect observed. Supernatant analysis in biological samples does not give a total Cd recovery for all of them. The detection limits observed for Cd were 0.05 and 0.2 mug l(-1) for supernatant and slurry analysis respectively in environmental samples, while in biological samples were 0.2 and 0.6 mug l(-1) for supernatant and slurry analysis, respectively. In all case the better precision was obtained for supernatant analysis (3-6%) than slurry analysis (6-12%). The results obtained by analysing different reference materials (sewage sludge, city waste incineration, Antarctic krill and human hair) showed good agreement with the certified value confirming the validity of such a method for Cd determination instead to wet digestion procedures.     

Synthesis, characterization and applications of pyrocatechol modified amberlite XAD-2 resin for preconcentration and determination of metal ions in water samples by flame atomic absorption spectrometry (FAAS)

A new chelating resin is prepared by coupling Amberlite XAD-2 with pyrocatechol through an azo spacer, characterized (by elemental analysis, IR and TGA) and studied for preconcentrating Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) using flame atomic absorption spectrometry (FAAS) for metal monitoring. The sorption is quantitative in the pH range 3.0-6.5, whereas quantitative desorption occurs instantaneously with 2 M HCl or HNO(3) The sorption capacity has been found to be in the range 0.023-0.092 mmol g(-1) of resin. The loading half time (t(1/2)) is 1.4, 4.8, 1.6, 3.2, 2.3 and 1.8 min, respectively for Cd, Co, Cu, Fe, Ni and Zn. The tolerance limits of electrolytes NaCl, NaBr, NaNO(3), Na(2)SO(4) and Na(3)PO(4) in the sorption of all the six metal ions (0.2 mug ml(-1)) are reported. The Mg(II) and Ca(II) are tolerable with each of them (0.2 mug ml(-1)) up to a concentration level of 0.01-1.0 M. The enrichment factor has been found to be 200 except for Fe and Cu for which the values are 80 and 100, respectively. The lowest concentration of metal ion for quantitative recovery is 5, 10, 20, 25, 10 and 10 mug l(-1) for Cd, Co, Cu, Fe, Ni and Zn, respectively. The simultaneous determination of all these metal ions is possible and the method has been applied to determine all the six metal ions in tap and river water samples (RSD相似文献   

Preconcentration and determination of trace elements with 2,6-diacetylpyridine functionalized Amberlite XAD-4 by flow injection and atomic spectroscopy

An on-line flow injection method for the direct determination of trace elements in environmental samples is described. A mini-column packed with 2,6-diacetylpyridine functionalized Amberlite XAD-4 was used to preconcentrate and separate 8 trace metals (Cd, Co, Cu, Mn, Ni, Pb, U and Zn) from water and extracts from solid samples. The metals were eluted with 0.1 M HNO(3) directly to the detection system (either inductively coupled plasma-mass spectrometry (ICP-MS) or flame atomic absorption spectrometry (FAAS)). As well as demonstrating that the resin could be used to preconcentrate ultra-trace analytes from natural waters, it was also shown to work well at a pH of 5.5. Therefore, after treatment of sample digests with sodium fluoride, samples that contain extremely large concentrations of iron may be analysed for trace analytes without the excess iron overloading the capacity of the resin. To this end, the analytes Cd, Co, Cu and Ni were preconcentrated from acid extracts of certified soil/sediment samples and then eluted with nitric acid to be determined on-line. Limits of detection (3sigma) of Cd = 0.33 microg l(-1), Co = 0.094 microg l(-1), Cu = 0.34 microg l(-1), Mn = 0.32 microg l(-1), Ni = 0.30 microg l(-1), Pb = 0.43 microg l(-1), U = 0.067 microg l(-1) and Zn = 0.20 microg l(-1) for the FI-ICP-MS system and Cd = 22 microg l(-1), Co = 60 microg l(-1), Cu = 10 microg l(-1) and Ni = 4.8 microg l(-1) for the FI-FAAS system were obtained. Analysis of certified reference materials showed good agreement with the certified values using the two methods.     

Trace metals analysis in estuarine and seawater by ICP-MS using on line preconcentration and matrix elimination with chelating resin

The main difficulties of trace metals analysis in estuarine and seawater stem from their very low concentration (mug/l to sub-mug/l), and, by contrast, the high salt content (up to 38 g/l in the Mediterranean Sea). ICP-MS allows multi-elemental analysis and offers great sensitivity, but may be strongly affected by matrix effects induced by high salt contents (> 1 g/l). To perform trace metals analysis both in riverine, estuarine and seawater, we have developed a hyphenated method: ion chelation chromatography coupled on-line with ICP-MS. Iminodiacetate resin, Metpac CC-1 (Dionex), was used to concentrate most of the trace metals, and to separate them from alkaline and alkaline-earth metals. Behaviour of 17 elements (Pb, Cu, Cd, Ni, U, Cr, Mn, Al, Co, Ga, In, Zn, V, Tl, Bi, Ag and Sn) towards the resin was qualitatively investigated. A method validation, partly derived from AFNOR standard XPT 90-210, was carried out on 12 elements (Pb, Cu, Cd, Ni, U, Cr, Mn, Al, Co, Ga, Bi and In). Replicate measurements of multi-elemental standard solutions were used to check linearity, and to determine repeatability and detection limits. Method accuracy was then assessed by analysing two certified materials: a synthetic freshwater (SRM 1643d), and a natural filtered coastal seawater (NRCC CASS-3). An application assay of natural samples from the Rh?ne river (France) was eventually carried out, and the analytical results were found to be consistent with previous works.     

Determination of beryllium and selenium in human urine and of selenium in human serum by graphite-furnace atomic absorption spectrophotometry.

For human urine beryllium (Be), each sample (500 microl) was diluted (1+1) with Nash reagent (containing 0.2% (v/v) acetylacetone and 2.0 M ammonium acetate buffer at pH 6.0) and then a 20-microl volume of Triton X-100 (0.4%, v/v) aqueous solution was added. An aliquot (10 microl) of the diluted urine mixture was introduced into a graphite cuvette and was atomized according to a temperature program. The method detection limit (MDL, 3sigma) for Be was 0.37 microg/l in the undiluted urine sample and the calibration graph was linear up to 65.0 microg/l. Calibration graphs were prepared by the standard addition method. Accuracies of 98.6-102% were obtained when testing standard reference material (SRM 2670) freeze dried human urine samples. Precision (relative standard deviation, RSD) for urine Be was < or = 2.3% (withinrun, n = 5) and was < or = 3.0% (between-run, n = 3). For human urine and serum selenium (Se), samples (100 microl) were diluted with HNO3 (0.2%, v/v) to make a (1+1) dilution for urine analysis or a (1+4) dilution for serum analysis. An additional aliquot (10 microl) of Triton X-100 (0.1%, v/v) was added to each 200 microl of (1+1) diluted urine (or 20 microl of the Triton X-100 was added to each 500 microl of (1+4) diluted serum) sample. After the diluted sample mixture (10 microl) was introduced into a graphite cuvette, the corresponding chemical modifier (10 microl, containing Ni2+ + Pd + NH4NO3 in HNO3 (0.2%, v/v)) was added to it and the mixture was atomized. The MDL (3sigma) for Se in urine and in serum was 4.4 and 21.4 microg/l in undiluted sample, respectively, and the calibration graphs were linear up to 150 and 400 microg/l. Accuracies of urine Se were 98.9 - 99.4% by testing SRM 2670 (NIST) urine standards with RSD (between-run, n = 3) within 2.9%; and that of serum Se was 97.2% when testing a certified second-generation human serum (No. 29, #664) with RSD (between-run, n = 3) of 1.4%. The proposed method can be applied easily, directly, and accurately to the measurement of Be and Se in real samples (including six urine Se and four serum Se from patients of Blackfoot Disease in Taiwan).     

Determination of trace amounts of some metals in samples with high salt content by atomic absorption spectrometry after cobalt-diethyldithiocarbamate coprecipitation

A method for determination of trace amounts of Cu, Fe, Pb, Mn, Zn, Cd, Ni, Bi and Cr in aqueous solutions by flame atomic absorption spectrometry after coprecipitation by using a combination of sodium diethyldithiocarbamate as a chelating agent and cobalt as a carrier element was introduced. Different factors including amounts of reagents, pH of sample solution, standing time, sample volume for the precipitation and matrix effects were examined. Under selected conditions, the relative standard deviation of the combined method of sample treatment, coprecipitation and determination with flame AAS (n = 9) is generally about 3.5-6.9%; the limits of detection (3 s, n = 20) for the analytes were found to be between 4 and 64 microg 1(-1). The procedure was applied to the analysis of sea water and dialysis concentrate samples with quantitative recovery, > or =95%.     

Several modified piezoelectric quartz crystals for determination of omethoate

A chromatographic method for the determination of transition metals in human hair samples is described. The method involves the separation of Cu, Pb, Zn, Ni, Co, Cd and Mn in a C18 column coated with sodium hexadecane-sulfonate (SHS) and spectrophotometric detection (520 nm) after post-column reaction of the eluted metals with 4-(2-pyridylazo)-resorcinol (PAR). The eluent was a 100 mM tartrate solution adjusted to pH 3.1 with a 2 M sodium hydroxide solution (flow-rate=1.0 ml min(-1)). A good separation of the eluted metals (specially for Cu/Pb and Zn/Ni) has been achieved. The detection limits, expressed as mug l(-1), were 2.2 (Cu), 8.0 (Pb), 2.8 (Zn), 1.5 (Ni), 1.5 (Co), 12.0 (Cd), and 1.4 (Mn). A microwave-assisted closed vessel acid digestion procedure with HNO(3)+HClO(4) (4+1 ml) was used for the hair samples solubilisation. Nineteen hair samples were analysed with the proposed method. The results were in good agreement with those obtained by atomic absorption spectrometry (AAS).     

Determination of metals in small samples by atomic absorption and emission spectrometry with discrete nebulization

Eight elements in NBS-SRM 1577 bovine liver and other biological standards are determined by flame atomic absorption (Ca, Cu, Fe, Mg, Mn and Zn) and emission (K and Na) spectrometry. Samples (2 mg) weighed into a 3.8-ml teflon vessel are decomposed with 40 μl of (5 ÷ 1) nitric—perchloric acids in a sealed teflon vessel. A 75-μl or 100-μl aliquot of the diluted sample solution is injected into a small teflon funnel coupled directly to the nebulizer needle of the spectrometer. The results obtained agree well with certified values: the standard deviation is about 2%.     

A novel fluorescence reagent, 10-hydroxybenzo[h]quinoline-7-sulfonate, for selective determination of beryllium(II) ion at pg cm(-3) levels.

A facile method has been developed for the highly sensitive and selective determination of ultratrace Be(II) ion using a new fluorimetric reagent, 10-hydroxybenzo[h]quinoline-7-sulfonate (HBQS), under extremely alkaline conditions, at pH 12.0. This reagent is quite suitable for the very small ion, Be(II), to form a 6-membered chelate ring, compatible with a high fluorescence yield. The stoichiometry of the chelate is 1:1 for Be-HBQS at pH 12.0. The calibration graph gave a wide linear dynamic range, 2-100 nmol dm(-3) of Be(II) ion with the detection limit (3s blank) of 0.52 nmol dm(-3), or 4.7 pg cm(-3). The excellent sensitivity and toughness toward the matrix influence were demonstrated using the artificial sample solutions for air-dust. Coupled with the simple masking procedure using EDTA, the method enables one to determine Be(II) ion at nanomolar levels in the presence of metals at the natural abundance levels in air-dust samples, typically Al, Ca, Cu, Fe, Mg, Pb, and Zn at 130, 150, 1.0, 70, 33, 3.0, and 8.0 micromol dm(-3), respectively, in the final solution. The proposed method was successfully applied to the determination of Be in urban air.     

Flame atomic absorption spectrometric determination of chromium(VI) by on-line preconcentration system using a PTFE packed column

A new, sensitive and robust time-based flow injection (FI) method for on-line preconcentration and determination of ultra trace amounts of chromium(VI) by flame atomic absorption spectrometry (FAAS) has been elaborated. The sample is initially mixed on-line with ammonium pyrrolidine dithiocarbamate (APDC) and the Cr(VI)-PDC chelate is absorbed quantitatively on a mini-column packed with polytetrafluoroethylene (PTFE) turnings at a pH range 0.8-1.4. The complex is subsequently eluted with isobutyl methyl ketone (IBMK) and introduced directly into the nebulizer-burner system. The optimized system offered improved performance characteristics, with unlimited lifetime of the proposed column. The enhancement factor was 80, for a 3-min preconcentration time and the sample frequency was 18 h(-1). The calibration curve was linear over the concentration range 1-40 mug l(-1) with a detection limit of c(L)=0.8 mug l(-1) and a relative standard deviation of s(r)=3.2%, at the 20 mug l(-1) level. The proposed method was evaluated by analyzing samples of certified and spiked water, and it was applied to the analysis of natural water samples and sediments.     

Determination of trace metals in waters and compost by on-line precipitation coupled to flame atomic absorption spectrophotometry or ion chromatography

A general rapid on-line preconcentration method for the determination of trace metals coupled to flame atomic absorption spectrophotometry (FAAS) or ion chromatography (IC) with spectrophotometric detection is described. The method is based on the on-line precipitation of metal hydroxides with sodium hydroxide and their dissolution in a small volume of nitric acid solution. All the chemical and physical variables that affect the efficiency of metal precipitation and elution in the flow injection system have been studied. The detection limits obtained by FAAS are 0.1, 0.3, 0.5 and 0.5 mug l(-1) for Zn, Cu, Ni and Pb, respectively. When the on-line precipitation is coupled to IC with post-column derivatization with the spectrophotometric reagent 4-(2-pyridylazo) resorcinol (PAR), the detection limits are 3, 1, 5, 3, and 3 mug l(-1) for Cu, Zn, Ni, Co and Mn, respectively. The proposed general method was successfully applied to determine independently the above mentioned metals in compost and tap and river water samples.     

Direct electrothermal atomic absorption spectrometry determination of nickel in sea water using multiple hot injection and Zeeman correction

Methods for the direct determination of Ni in sea water samples by ETAAS were developed using Zeeman effect background correction system (ZEBC) and a multi-injection technique. A mass of palladium nitrate of 2.5 mug (for an injection volume of 100 mul) was used as chemical modifier. The optimum pyrolysis and atomization temperatures were 1700 and 2100 degrees C, respectively. The characteristic mass (m(0)) and characteristic concentration (C(0)), precision and accuracy were studied for different injection volumes (20, 100 and 200 mul). For an injection volume of 100 mul (five 20 mul aliquot) of sample the accuracy analysis of different certified materials (saline and non saline water) was agreeable. The total time of the proposed procedure is 6 min. A m(0) and C(0) of 34.5 pg and 0.3 mug l(-1), respectively were obtained for this injection volume (100 mul). Finally, interferences from major and minor components of sea water was studied.