Simultaneous Multi-element Atomic Absorption Research Articles

Evaluation of internal standardization for the determination of semivolatile analytes in difficult matrices by simultaneous multielement atomic absorption spectrometry

The aim of the present work is to investigate the use of the internal standardization technique combined with permanent chemical modification for the determination of two semivolatile analytes, such as As and Se, in difficult matrices by electrothermal atomic absorption spectrometry. Bismuth and tellurium have been evaluated as internal standards to minimize matrix effects on the direct determination of selenium and arsenic in sediments, by simultaneous electrothermal atomic absorption spectrometry using graphite tubes with integrated platform, pre-treated with different masses of Zr and Ir as permanent modifier. A Perkin-Elmer SIMAA 6000 simultaneous multielement spectrometer was used to study the correlation between two integrated absorbance signals. Matrix effects were evaluated by calculating the slope ratio between the analytical curve obtained from reference solutions prepared in 1.0% (v/v) HNO3 and analytical curve obtained from IS additions in matrix solutions. The results showed that Te was the optimal internal standard and 200μg Zr and 20μg Ir was the optimal permanent chemical modifier for both analytes. The instrumental limits of detection for As and Se were 1.48 and 1.96μgL−1 without the use of an internal standard and 0.59 and 0.35μgL−1 when Te was used as an internal standard, respectively. Relative standard deviations for a sample with matrix effect containing 100μgL−1 As and 200μgL−1 Se were 1.3% and 2.3% (n=20) using 100μgL−1 Te, respectively, and for a standard solution sample containing 100μgL−1 As and 200μgL−1 Se were 3.0% and 1.2% (n=20) using 100μgL−1 Te, respectively. The accuracy of the proposed method was evaluated by an addition-recovery experiment and by the analysis of different certified reference materials. The recovered values were in the 95–100% range for both analytes.

Alternative approaches to correct interferences in the determination of boron in shrimps by electrothermal atomic absorption spectrometry

The aim of this study is to propose alternative techniques and methods in combination with the classical chemical modification to correct the major matrix interferences in the determination of boron in shrimps. The performance of an internal standard (Ge) for the determination of boron by the simultaneous multi-element atomic absorption spectrometry was tested. The use of internal standardization increased the recovery from 85.9% to 101% and allowed a simple correction of errors during sampling preparation and heating process. Furthermore, a new preparation procedure based on the use of citric acid during digestion and dilution steps improved the sensitivity of the method and decreased the limit of detection. Finally, a comparative study between the simultaneous multi-element atomic absorption spectrometry with a longitudinal Zeeman-effect background correction system, equipped with a transversely-heated graphite atomizer and the single element atomic absorption spectrometry with a D2 background correction system, equipped with an end-heated graphite atomizer was undertaken to investigate the different behavior of boron in both techniques. Different chemical modifiers for the determination of boron were tested with both techniques. Ni-citric acid and Ca were the optimal chemical modifiers when simultaneous multi-element atomic absorption spectrometry and single-element atomic absorption spectrometry were used, respectively. By using the single-element atomic absorption spectrometry, the calculated characteristic mass was 220pg and the calculated limit of detection was 370μg/kg. On the contrary, with simultaneous multi-element atomic absorption spectrometry, the characteristic mass was 2200pg and the limit of detection was 5.5mg/kg.

Concentration Levels of Trace Elements in Carrots, Onions, and Potatoes Cultivated in Asopos Region, Central Greece

The objective of the work was to investigate the correlation between the environmental pollution of Asopos river area in Viotia, Greece and the concentration of Ni, Cr, Cd, Pb, Cu, and As in specific crops (carrots, onions, and potatoes) produced in this region. Samples of these crops from Asopos and other Greek areas (control) were collected. For method accuracy, the Certified Reference Material, CRM 281 (trace elements in rye grass) was measured. Simultaneous multi-element graphite furnace atomic absorption spectrometry was used after a microwave acid digestion. The levels of Ni in Asopos food were found up to 9 times higher than control (e.g., Asopos potatoes had an average Ni content of 800 µg/kg compared to 78 µg/kg in control, whereas Asopos carrots had an average Ni content of 474 µg/kg compared to 93 µg/kg in control). Likewise, the levels of Cr were found to be about 2 times higher than control (e.g., Asopos carrots were found to have an average Cr content of 43 µg/kg compared to 20 µg/kg in control). The levels of Cd and Pb had a high variance in the Asopos sourced food. Arsenic was not detected in any sample. Our results indicate that the mean intake of trace elements (Ni, Cr, Pb, Cd, and Cu) by adults through consumption of crops from Asopos, for an average consumption pattern, generally is well below the Allowable Daily Intakes (ADIs). Comparison was also made with data from literature from Greece.

In vitro evaluation of Cu and Fe bioavailability in cashew nuts by off-line coupled SEC–UV and SIMAAS

In this work Cu and Fe bioavailability in cashew nuts was evaluated using in vitro method. Extractions with simulated gastric and intestinal fluids and dialysis procedures were applied for this purpose. The proteins separation and quantification were performed by size exclusion chromatography (SEC) coupled on-line to ultra-violet (UV) and off-line to simultaneous multielement atomic absorption spectrometry (SIMAAS). The SEC–UV and SIMAAS profiles of the protein fractions obtained by alkaline extraction (NaOH) and precipitation with HCl indicated the presence of high and low molecular weight species in the range between >75 kDa and 9.3 kDa. Almost 83% of Cu and 78% of Fe were extracted during cashew nut digestion and 90% of both elements were dialyzed. With these results it is possible to assume that 75% of Cu and 70% of Fe present in cashew nut could be bioavailable. The SEC–UV and SIMAAS chromatographic profiles obtained after in vitro gastrointestinal digestion reveal that Cu and Fe not dialyzed can be associated to a compound of 9.2 kDa.

Mn and Cu concentrations in mixed saliva of elementary school children in relation to sex, age, and dental caries

To examine the standard Mn and Cu concentrations in mixed saliva from children and the relationship between these levels and dental caries, resting mixed saliva samples obtained from 527 children of an elementary school in Kitakyushu City were collected at 10:00–11:30 a.m. during December 2004. The Mn and Cu concentrations were determined using simultaneous multi-element atomic absorption spectrometry. The standard Mn and Cu levels were 22.0±15.2 and 3.8±4.1 ng/mL, respectively, in the sound teeth group. Mn levels were significantly higher in boys (25.4±17.4 ng/mL) than girls (19.1±12.3 ng/mL) and also higher in upper (25.5±16.4 ng/mL) than lower (19.0±13.5 ng/mL) grades. The Cu level was unaffected by sex and age in the sound teeth group. The Cu level in children with caries experience (5.7±5.3 ng/mL) was significantly higher than that of the sound teeth group. Moreover, the Cu levels in children with untreated caries were significantly higher than that of the sound teeth group, and increased with the number of untreated teeth. No significant difference was found in the Cu concentrations between the group in which all decayed teeth were treated and the sound teeth group. The Mn levels were similar with or without caries and treatment. These findings indicate that the Mn level in mixed saliva depended on sex and age, and suggest the possibility of Cu dissolving into mixed saliva by demineralization due to dental caries.

Evaluation and application of bismuth as an internal standard for the determination of lead in wines by simultaneous electrothermal atomic absorption spectrometry.

A method for the direct determination of Pb in wines by simultaneous multi-element atomic absorption spectrometry (SIMAAS) using a transversely heated graphite atomizer, Zeeman-effect background corrector and internal standardization is proposed. Bismuth was used as an internal standard and Pd(NO3)2 plus Mg(NO3)2 as chemical modifier to stabilize both the analyte and the internal standard. The implementation of two pyrolysis steps avoided any build-up of carbonaceous residues on the graphite platform. All diluted samples (1 + 1 v/v) in 0.2% v/v HNO3 and reference solutions (5.0-50 microg l(-1) Pb in 0.2% v/v HNO3) were spiked with 25 microg l(-1) Bi. For a 20 microl aliquot dispensed into the graphite tube, a good correlation (r = 0.9997) was obtained between the ratio of the analyte signal to the internal standard signal and the analyte concentration of the reference solutions. The electrothermal behaviour of Pb and Bi in red, white and rosé wines were compared. In addition, absorbance variations due to changes in experimental conditions, such as atomizer temperature, integration time, injected sample volume, radiation beam intensity, graphite tube surface, dilution and sample composition, were minimized by using Bi as internal standard. Relative standard deviations of measurements based on integrated absorbance varied from 0.1 to 3.4% and from 0.5 to 7.3% (n = 12) with and without internal standard correction, respectively. Good recoveries (91-104%) for Pb spikes were obtained. The characteristic mass was 45 pg Pb and the limit of detection based on integrated absorbance was 0.9 microg l(-1) Pb. Internal standardization increased the lifetime of the tube by 25%. Direct determinations of Pb in wines with and without internal standardization approaches were in agreement at the 95% confidence level. The repeatability and the tube lifetime were improved when using Bi as internal standard. The improvement in accuracy using an internal standard was only observed when the analytical results were affected by errors.

Determination of Lead, Cadmium, Arsenic and Nickel in Atmospheric Particulate Matter by Simultaneous Multi-Element Electrothermal Atomic Absorption Spectrometry

A simple method for the determination of lead, cadmium, arsenic and nickel in atmospheric particulates by simultaneous multi-element Electrothermal Atomic Absorption Spectrometry has been developed. Due to the high concentrations of Pb and low concentrations of Cd, As and Ni found in particulate matter, lead was monitored at 261.4 nm and the other analytes at the usual wavelengths. Two approaches have been compared using aqueous standard solutions and acid extracts of particulate matter samples. First, a fast electrothermal programme, without chemical modifier, and a short pyrolysis step at 500°C for 10 s, has been developed. The omission of the pyrolysis step was not possible, because strong interference on arsenic was observed. The characteristic masses determined with this approach were 2.10 ng for Pb, 2.0 pg for Cd, 35.8 pg for As and 27.5 pg for Ni. The corresponding detection limits were 4.2 μg l−1 (Pb), 0.025 μg l−1 (Cd), 0.42 μg l−1 (As) and 1.5 μg l−1 (Ni), respectively. The second approach utilized the addition of Pd/Mg modifier (5 μg + 5 μg). The pyrolysis temperature (Tpyr) could be raised up to 650°C. The characteristic masses were 1.40 ng (Pb), 2.2 pg (Cd), 37.3 pg (As) and 27.9 pg (Ni). In the presence of Pd/Mg modifier the limits of detection were 4.3 μg l−1 (Pb), 0.020 μg l−1 (Cd), 0.26 μg l−1 (As) and 0.97 μg l−1 (Ni), respectively. These two approaches were applied in the determination of Pb, Cd, As and Ni in atmospheric particulates. Matrix matched calibration was used in order to achieve accurate and precise results. The calculated recoveries, in the absence of chemical modifiers, were 128% for Pb, 124% for Cd, 108% for As and 110% for Ni. The calculated recoveries were consistently better in the presence of the mixed Pd/Mg modifier: 101% (Pb), 99.7% (Cd), 103% (As) and 102% (Ni), respectively.

An improved impaction-graphite furnace system for the direct and near real-time determination of cadmium, chromium, lead and manganese in aerosols and cigarette smoke by simultaneous multielement atomic absorption spectrometry

The design, operating characteristics, and preliminary evaluation of an improved impaction-graphite furnace system, based on a theoretical study of particle size collected, are presented. After direct collection, the graphite furnace from the system is inserted in an atomic absorption spectrometer for analysis by simultaneous multielement atomic absorption spectrometry. This system has the potential for the direct and near real-time (few minutes) determination of metals in aerosols. The system has been preliminarily evaluated using aqueous solutions of chromium, and has then been applied to the determination of cadmium, chromium, lead, and manganese in cigarette smoke. Results show an increase ranging from almost five (lead) to sixteen (cadmium) over background levels.

Simultaneous multielement determination in complex matrices using frequency-modulated electrothermal atomic absorption spectrometry

This work presents the simultaneous multielement atomic absorption spectrometric (FREMSAAS) determination of cadmium and lead, iron and chromium, and cooper and manganese in several complex matrices. Four certified reference materials were chosen for the evaluation of the accuracy of the frequency-modulated method in routine analysis. For the determination of complex matrices, the use of a matrix modifier is unavoidable. The spectrometer is equipped with deuterium background correction. The instrumentation is presented as well as the procedures of preparation and determination and the resulting values are discussed. The samples were prepared through digestion with aqua regia according to DIN 38414 for sewage sludges and sediments. Determinations with a commercial Perkin-Elmer ZL-4100 AAS are carried out as reference. All resulting values were mathematically treated using statistical tests which have been recommended for quality control purposes.

Frequency-modulated simultaneous multielement atomic absorption spectrometry using electrothermal atomizer and deuterium background correction

Characteristic data of the frequency-modulated simultaneous multielement atomic absorption spectrometry (FREMSAAS) using electrothermal atomizer with deuterium background correction, have been determined. The data obtained have been processed by using several statistical tests recommended for quality control purposes. The instrumentation has been presented as well as procedures of separating elements into measure groups and fixing of variable conditions. Detection limits, characteristic masses and working ranges have been given for the eleven elements examined. The data have been in good agreement to results obtained with conventional one-channel AAS instruments. The eleven elements have been simultaneously determined in a standard reference material (SRM) and all results are compatible with a 95% certainty with the certified values. FREMSAAS has been applied to a real sample.

Simultaneous multielement graphite furnace atomic absorption measurements using a photodiode array detector

A photodiode array detector multichannel analyser system has been coupled to a graphite furnace atomizer and tested for simultaneous multielement atomic absorption analysis. Multielement hollow cathode lamps are used as light sources and spectral lines are dispersed through a spectrograph with three selectable gratings. Multiple transmitted spectra are recorded to simultaneously determine the atomic absorption profiles of the analyte elements during the atomization stage. Atomic absorbance of individual elements is obtained by integrating the respective peak areas of the appropriate time-resolved atomic absorption spectra. The obtained sensitivities for Ni-Co-Fe are within the same order of magnitude as those from conventional single element determinations using photomultiplier tube detection. The system has also been applied for simultaneous multielement flame atomic absorption spectrometry (AAS) measurements and it has been demonstrated that background absorption can be readily corrected for both flame and graphite furnace AAS by a two-line method where non-atomic absorption lines can be chosen from the simultaneously recorded spectra.

Background correction in frequency modulated simultaneous atomic absorption spectrometry

For a long time simultaneous multielement determination by AAS has been a subject of intensive research. In this work a simultaneous multielement atomic absorption spectrometry method is described in a special new arrangement, called frequency modulated simultaneous AAS (FremsAAS), using fiberoptics, interference filters and frequency modulation and demodulation by lock-in amplifiers as main devices. Purpose of this work was to equip the FremsAAS with a D2-background correction and to test it with certified reference materials. Mn, Cd, Pb, Cu, Ni, Cr and Zn had been determined simultaneously (three at a time) in sewage sludge (BCR/CRM 146), estuarine sediment (BCR/CRM 277) and phosphate rock (BCR/CRM 32) with good feasibility. Frequency modulated simultaneous AAS with background correction (FremsAASUK) represents an interesting alternative to known instruments.

尿中重金属の同時多元素原子吸光分析による正常値の測定

尿中重金属の同時多元素原子吸光分析による正常値の測定

尿中重金属の同時多元素分析法および分析上の留意点について

The methods of simultaneous analysis of heavy metals in urine using simultaneous multielement atomic absorption spectrophotometry were examined. Seven elements, Co, Cr, Cu, Mn, Ni, Pb, Cd, important as environmental chemical hazards were examined concerning, analytical method, term and cautionary points for human urine analyses. Analytical method of creatinine in urine was improved with no reexaminations. Standard added method is superior to the working curve method for human urine analyses.Highly precise urine analysis is possible by the standard added method without consideration for deterioration of source of light.

SIMULTANEOUS DETERMINATION OF TRACE ELEMENTS IN URINE BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

Trace amounts of cadmium, chromium, nickel, and lead in urine were determined by simultaneous mltielement graphite furnace atomic absorption spectrometry. Palladium chloride was employed as a matrix modifier. The urine was diluted 1+1 with distilled water, and introduced into simultaneous multielement atomic absorption spectrophotometer together with palladium solution. Standard addition methods were recommended for these elements analysis. Cadmium, chromium, nickel and lead contents determined by the proposed method ranged 0.2-2.4μ/l, 1.0-3.0μ/l, 0.2-4.8μ/l. and 5.0-10.0μ/l. respectively.

Slurry sample preparation for simultaneous multi-element graphite furnace atomic absorption spectrometry

Simultaneous multi-element graphite furnace atomic absorption spectrometric analysis of solids prepared as slurries is investigated. Slurries were prepared using 5–10 mg of sample and 5 ml of dilute nitric acid. Analyses were performed on a simultaneous multi-element atomic absorption spectrometer with a continuum source (SIMAAC) using platform atomisation, integrated absorbance measurements, 20-µl sample volumes and calibration standards prepared in 5% HNO3. As many as seven elements were determined simultaneously in a total of ten different National Bureau of Standards (NBS) reference materials representing a wide variety of sample matrices. Ultrasonic agitation of the slurry preparations proved useful in avoiding setting of the particles. Typically, average accuracies of 100 ± 12% were observed.

Human albumin as a reference material for trace elements

An investigation through interlaboratory comparison using different analytical techniques has been carried out in order to assess the suitability of a plasma protein solution as a source for a trace element reference material in clinical analysis. Reasonable agreement was obtained for a number of elements from the range studied: Al, Ba, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Sr, V and Zn. The techniques used included flame and furnace atomic absorption spectrometry (FAAS and ETA-AAS), furnace atomic emission spectrometry (ETA-AES), inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and simultaneous multi-element atomic absorption spectrometry (SIMAAC). Results indicated that this plasma protein solution may prove useful as a source for a reference material covering trace element levels outwith the range found in normal human plasma.

Simultaneous multi-element analysis by continuum source atomic absorption spectrometry with a spatially and temporally isothermal graphite furnace

The performances of three furnace systems were compared with respect to conditions for multi-element atomic absorption spectrometry (AAS), interference effects and carry-over contamination, when operated with a simultaneous multi-element atomic absorption continuum source spectrometer (SIMAAC). The three systems were a Perkin-Elmer HGA-500, an integrated contact cuvette furnace (spatially isothermal) and a two-step atomiser (spatially and temporally isothermal). High atomisation temperatures must be used in multi-element AAS if non-volatile elements are to be included. Therefore the facility of the two-step atomiser for selecting optimum temperatures regardless of the volatility of an element cannot be fully exploited. However, by using a consecutive two-stage constant-temperature atomisation procedure, optimum sensitivity could be achieved for volatile as well as refractory elements. The two furnace systems providing spatial isothermality were in general less susceptible to interference effects and, in addition, offered a significant reduction in carry-over contamination. This is of special importance in the SIMAAC system in order to utilise its facility of a dynamic calibration range of 5–6 orders of magnitude for each element.

Optimisation of flame parameters for simultaneous multi-element atomic absorption spectrometric determination of trace elements in rocks

A study is described that identifies the optimum operating conditions for the accurate determination of Co, Cu, Mn, Ni, Pb, Zn, Ag, Bi and Cd using simultaneous multi-element atomic absorption spectrometry. Accuracy was measured in terms of the percentage recoveries of the analytes based on certified values in nine standard reference materials. In addition to identifying optimum operating conditions for accurate analysis, conditions resulting in serious matrix interferences and the magnitude of the interferences were determined. The listed elements can be measured with acceptable accuracy in a lean to stoicheiometric flame at measurement heights ⩽5–10 mm above the burner.

高周波誘導結合プラズマを原子化源とし，水銀キセノンランプを光源とする原子吸光分光分析法

Simultaneous multielement atomic absorption spectrometry using a mercury-xenon lamp and inductively coupled plasma (ICP) was studied. The ICP was used for the atomization and ionization of analytes, and the mercuryxenon lamp was used as a light source which provided a strong continuum emission spectrum over a wide wavelength range.Effects of the carrier gas flow rate, rf power and the height of optical axis on the absorbed spectral intensity were investigated. Detection limits of Ni, Fe, V, Sn, Si and Pb were lower than those obtained by ICP-atomic emission spectrometry. Linear dynamic ranges of typically three orders of magnitude were observed.