Simultaneous Determination Of Elements Research Articles

Spectrometers with MAES analyzers based on new photodetector arrays

Multichannel analyzers of emission spectra (MAES) are operated as part of more than six hundred systems for atomic emission spectral analysis at enterprises in Russia, the CIS countries, and others. Until recently, MAES analyzers used only BLPP-369M1 photodetector arrays, whose performance is sufficient for integral atomic emission spectrometry applications using bright sources of spectral excitation based, for example, on an arc or spark electric discharge. To solve problems where high temporal spatial resolution and high sensitivity are required, high-speed MAES analyzers have been developed based on two new photodetector arrays—BLPP-2000 and BLPP-4000. A number of optical spectrometers based on these arrays have been developed and put into production by the VMK-Optoelektronika company: Atomic emission spectrometers: Grand Globula and Ekspress arc and spark spectrometers for the direct analysis of powders by evaporation from the channel of a graphite electrode and for the analysis of metals; Grand-Potok arc spectrometers for the rapid analysis of powders by the spill-injection method; Grand-Ekspert and Favorit argon-spark vacuum spectrometers for the rapid analysis of metals and alloys; Grand-SVCh microwave-induced nitrogen plasma spectrometers and Grand-ISP inductively-coupled argon plasma spectrometers for the analysis of liquids; Kolibri-SVCh microwave-induced air plasma spectrometers and Pavlin flame atomic emission spectrometers for the determination of alkaline and alkaline earth elements in solutions. Grand-AAS high-resolution continuous-source electrothermal atomic absorption spectrometers for the simultaneous determination of elements in liquids.

Microwave-assisted digestion with a single reaction chamber for mineral fertilizer analysis by inductively coupled plasma optical emission spectrometry

ABSTRACTA systematic approach is proposed to evaluate microwave-assisted digestion in a single reaction chamber for the simultaneous determination of elements in the mineral fertilizer and raw material by inductively coupled plasma optical emission spectrometry. A reference material was digested using 12 acid mixtures containing nitric, hydrochloric, orthophosphoric, hydrofluoric or boric acid. Principal components analysis was applied for data treatment. Three digestion procedures based on diluted acids exhibited the most accurate results, with relative errors for reference values ranging from −15% to + 9%. Limits of quantification were in the range of 0.2 mg cadmium kg−1 up to 1000 mg aluminum kg−1.

A novel method for simultaneous determination of selected elements in dolomite and magnesia by Inductively Coupled Plasma Atomic Emission Spectroscopy with slurry sample introduction

The slurry nebulization ICP-AES method for simultaneous determination of selected elements in dolomite and magnesia was proposed. Based on the investigation results the optimal conditions for this analysis were as follows: particle size <40μm, the nitric acid concentration 10%, the RF power 1.0kW, aqueous solutions (no dispersing agents) and mixing on magnetic stirrer, during the sample introduction into plasma, as homogenization method. The certified reference materials Dolomite CRM 782-1 and High Purity Magnesia BCS-CRM 389/1 were analyzed. Student's t-test proved that there were no statistically significant differences between determined values and the certified ones. This proves that the slurry sample introduction into plasma in ICP-AES technique can be applied for simultaneous determination of elements in dolomite and magnesia.

Simultaneous spectrophotometric determination of copper, cobalt, nickel and iron in foodstuffs and vegetables with a new bis thiosemicarbazone ligand using chemometric approaches

A newly synthesized bis thiosemicarbazone ligand, (2Z,2′Z)-2,2′-((4S,5R)-4,5,6-trihydroxyhexane-1,2-diylidene)bis(N-phenylhydrazinecarbothioamide), was used to make a complex with Cu2+, Ni2+, Co2+ and Fe3+ for their simultaneous spectrophotometric determination using chemometric methods. By Job’s method, the ratio of metal to ligand in Ni2+ was found to be 1:2, whereas it was 1:4 for the others. The effect of pH on the sensitivity and selectivity of the formed complexes was studied according to the net analyte signal (NAS). Under optimum conditions, the calibration graphs were linear in the ranges of 0.10–3.83, 0.20–3.83, 0.23–5.23 and 0.32–8.12mgL−1 with the detection limits of 2, 3, 4 and 10μgL−1 for Cu2+, Co2+, Ni2+ and Fe3+ respectively. The OSC-PLS1 for Cu2+ and Ni2+, the PLS1 for Co2+ and the PC-FFANN for Fe3+ were selected as the best models. The selected models were successfully applied for the simultaneous determination of elements in some foodstuffs and vegetables.

Method for the determination of cadmium, lead, nickel, cobalt and copper in seafood after dispersive liquid–liquid micro-extraction

A method using dispersive liquid–liquid micro-extraction (DLLME) and detection by inductively coupled plasma optical emission spectroscopy (ICP-OES) was developed for the determination of trace elements in seafood samples. The procedure allowed the simultaneous determination of Cd(II), Pb(II), Ni(II) Cu(II) and Co(II) after pre-concentration using sodium diethyldithiocarbamate (DDTC) as a chelating agent. Under optimised conditions, the method had a limit of detection (LOD) of 0.03, 0.11, 0.12, 0.18 and 0.12 µg l−1 for Cd(II), Pb(II), Ni(II) Cu(II) and Co(II), respectively. The following enrichment factors were obtained: 16 (Cd), 34 (Pb), 20 (Ni) 34 (Cu) and 12 (Co). The procedure was applied for the determination of these elements in seafood (shrimp, mussel, bass and mullet) samples. The method is simple, efficient and easy to perform for the simultaneous determination of elements in seafood samples by ICP-OES.

A miniaturized capacitively coupled plasma microtorch optical emission spectrometer and a Rh coiled-filament as small-sized electrothermal vaporization device for simultaneous determination of volatile elements from liquid microsamples: Spectral and analytical characterization

A low power and low argon consumption (13.56MHz, 15W, 150mlmin−1) capacitively coupled plasma microtorch interfaced with a low-resolution microspectrometer and a small-sized electrothermal vaporization Rh coiled-filament as liquid microsample introduction device into the plasma was investigated for the simultaneous determination of several volatile elements of interest for environment. Constructive details, spectral and analytical characteristics, and optimum operating conditions of the laboratory equipment for the simultaneous determination of Ag, Cd, Cu, Pb and Zn requiring low vaporization power are provided. The method involves drying of 10μl sample at 100°C, vaporization at 1500°C and emission measurement by capture of 20 successive spectral episodes each at an integration time of 500ms. Experiments showed that emission of elements and plasma background were disturbed by the presence of complex matrix and hot Ar flow transporting the microsample into plasma. The emission spectrum of elements is simple, dominated by the resonance lines. The analytical system provided detection limits in the ngml−1 range: 0.5(Ag); 1.5(Cd); 5.6(Cu); 20(Pb) and 3(Zn) and absolute detection limits of the order of pg: 5(Ag); 15(Cd); 56(Cu); 200(Pb) and 30(Zn). It was demonstrated the utility and capability of the miniaturized analytical system in the simultaneous determination of elements in soil and water sediment using the standard addition method to compensate for the non-spectral effects of alkali and earth alkaline elements. The analysis of eight certified reference materials exhibited reliable results with recovery in the range of 95–108% and precision of 0.5–9.0% for the five examined elements. The proposed miniaturized analytical system is attractive due to the simple construction of the electrothermal vaporization device and microtorch, low costs associated to plasma generation, high analytical sensitivity and easy-to-run for simultaneous multielemental analysis of liquid microsamples.

Simultaneous determination of Mn2+ and Fe3+ as 4,4′[(4-cholorophenyl)methylene] bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) complexes in some foods, vegetable and water samples by artificial neural networks

A simple and sensitive spectrophotometric method to the simultaneous determination of Mn2+ and Fe3+ in foods, vegetable and water sample with the aid of artificial neural networks (ANNs) is described. It relies on the complexation of analytes with recently synthesised bis pyrazol base ligand as 4,4′[(4-cholorophenyl)methylene] bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)(CMBPP). The analytical data show that the ratio of ligand to metal in metal complexes is 1:1 and 1:2 for Fe3+ and Mn2+, respectively. It was found that the complexation reactions are completed at pH 6.7 and 5min after mixing. The results showed that Mn2+ and Fe3+ could be determined simultaneously in the range of 0.20–7.5 and 0.30–9.0mgl−1, respectively. The analytical characteristics of the method such as the detection limit and the relative standard error predictions were calculated. The data obtained from synthetic mixtures of the metal ions were processed by radial basis function networks (RBFNs) and feed forward neural networks (FFNNs). The optimal conditions of the neural networks were obtained by adjusting various parameters by trial-and-error. Under the working conditions, the proposed methods were successfully applied to the simultaneous determination of elements in different water, tablet, rice, tea leaves, tomato, cabbage and lettuce samples.

Low power capacitively coupled plasma microtorch for simultaneous multielemental determination by atomic emission using microspectrometers

A new, low power capacitively coupled plasma microtorch (30 W, 13.56 MHz, 0.5 L min −1 Ar) was investigated in conjunction with commercially available microspectrometers for the simultaneous multielemental analysis by atomic emission spectrometry of liquid samples without desolvation. Emission spectrum is simpler than in ICP-AES, the resonance lines are the most intense, so that a microspectrometer with FWHM of at least 1.5 nm is satisfactory for the record. The deviation from the Boltzmann distribution for Fe I has demonstrated the departure from the LTE in plasma. The non-spectral matrix effects of Li, Na, K, Ca and Mg on analytes emission are depressive and depend on matrix volatility, ionization potential of the interferent and analyte excitation energy. The detection limits (μg mL −1) are in the range 0.003 (Li) and 1.5 (Mn). The use of the standard additions method allowed the simultaneous determination of elements in environmental certified reference materials with overall recovery of 95 ± 10% and relative standard deviation of 1.7–8.2%. Compared to the traditional ICP, the microtorch has a simple construction, runs at low argon flow and can be integrated in a portable system suitable for in-situ simultaneous determination of elements.

Estimation of honey authenticity by multielements characteristics using inductively coupled plasma-mass spectrometry (ICP-MS) combined with chemometrics

In our study the mineral content of 55 honey samples, which represented three different types of honey: honeydew, buckwheat and rape honey from different areas in Poland, was evaluated. Determination of 13 elements (Al, B, Ba, Ca, Cd, Cu, K, Mg, Mn, Na, Ni, Pb, Zn) was performed using inductively coupled plasma-mass spectrometry. We tried to prove that the analysis of quality and quantity of honey elements could be used to define honey origin by using ICP-MS as a technique for simultaneous determination of elements. Chemometric methods, such as CA and PCA, were applied to classify honey according to mineral content. CA showed three clusters corresponding to the three botanical origins of honey. PCA permitted the reduction of 13 variables to four principal components explaining 77.19% of the total variance. The first most important principal component was strongly associated with the value of K, Al, Ni and Cd. This study revealed that CA and PCA analysis appear useful tools for differentiation of honey samples authenticity using the profile of mineral content and they highlighted the relationship between the elements distribution and honey type.

Development of a Partial Least-Squares Calibration Model for Simultaneous Determination of Elements by Inductively Coupled Plasma-Atomic Emission Spectrometry

A partial least-squares (PLS) calibration model was developed for simultaneous multicomponent elemental analysis with inductively coupled plasma-atomic emission spectrometry (ICP-AES) in the presence of spectral interference. The best calibration model was obtained using a PLS2 algorithm. Validation was performed with an artificial test set. Multivariate calibration models were constructed using 2 series of synthetic mixtures (Zn, Cu, Fe, and U, V). Accuracy of the method was evaluated with unknown synthetic and real samples.

Simultaneous determination of calcium, magnesium and zinc in different foodstuffs and pharmaceutical samples with continuous wavelet transforms

This work presents novel and very simple spectrophotometric methods by ratio spectra–continuous wavelet transformation for the simultaneous determination of ternary mixtures of calcium, magnesium and zinc without prior separation steps. The methods are based on the complexation reaction of these elements with bromopyrogallo red (BPR) at pH 9.4. The results showed that calcium, magnesium and zinc could be determined simultaneously in the range of 0.1–3.5 mg L −1, 0.2–3.2 mg L −1 and 0.5–3.8 mg L −1, respectively. Mexican hat and Morlet from the family of continuous wavelet transforms were selected and applied under the optimal conditions for multi-component determinations. In this study for improving the sensitivity the normalized spectra of divisors were used instead of standard spectrum of divisor. The method was tested by analyzing various synthetic ternary mixtures of Ca 2+, Mg 2+ and Zn 2+. Under the working conditions, the proposed methods were successfully applied to simultaneous determination of elements in cows’ milk, powder milk, pharmaceutical product and tea samples.

Simultaneous determination of hydride forming (As, Bi, Ge, Sb, Se, Sn) and Hg and non-hydride forming (Ca, Fe, Mg, Mn, Zn) elements in sonicate slurries of analytical samples by microwave induced plasma optical emission spectrometry with dual-mode sample introduction system

A slurry sampling method for the simultaneous determination of hydride forming (As, Bi, Ge, Sb, Se, Sn) and Hg and non-hydride forming (Ca, Fe, Mg, Mn, Zn) elements, without total sample digestion has been developed using the commercial dual-mode sample introduction system (MSIS) coupled with microwave induced plasma optical emission spectrometry (MIP-OES) from biological and environmental reference materials and real samples. The main advantage of this system is its simultaneous determination of elements that form volatile vapor species and elements that do not, without any instrumental changes. Optimization of reaction, nebulization and instrumental conditions was performed to characterize the new system. Slurry concentration up to 4% m/v (particles < 100 μm) prepared in 10% HNO 3 containing 100 μL of decanol, by application of ultrasonic agitation, was used with calibration by the standard addition technique. An ultrasonic probe was used to homogenize the slurry in the quartz cup just before its introduction into the reaction/nebulization system; the multimode sample introduction system (MSIS) combines the benefits of nebulization and vapor generation in a single device. Detection limits (LOD, 3 σ blank, peak area) of 0.07, 0.29, 0.25, 0.10, 0.12, 0.14, 0.11, 0.28, 0.42, 0.02, 0.21 and 0.34 μg g − 1 were obtained for As, Bi, Ge, Sb, Se, Sn, Hg, Ca, Fe, Mg, Mn and Zn, respectively. The relative standard deviations were ca. 10%, adequate for slurry analysis. To test the accuracy, six certified reference materials were analyzed with the analyte concentrations mostly in the μg g − 1 level. Measured concentrations are in satisfactory agreement with certified values for the biological reference materials (LUTS-1, DOLT-2) and environmental reference materials (PACS-1, GWB 07302, NIST 2710, NBS 1633b), all adequate for slurry sampling. The method was successfully applied to the determination of the elements in real samples (coal fly ash, lake sediment, sewage). The method requires small amounts of reagents and reduces contamination and losses.

Performance of a new nebulizer system for simultaneous determination of Sb, Sn (hydride generation), V, and Zn by ICP–OES

A new nebulizer system is described that extends the analytical capability of the inductively coupled plasma technique to include the simultaneous determination of two elements Sb and Sn (hydride-forming), with two conventional elements, V and Zn. The main advantage of this system is its simultaneous determination of elements that form volatile hydrides and elements that do not, without any instrumental changes. Optimization of reaction and instrumental conditions was performed to characterize the new system. The performance of the new nebulizer system was evaluated by studying the effect of some transition metals (Ni, Cu, Co, and Fe, 1-1000 mg L(-1)) on the Sb, Sn, V, and Zn emission signals (1 mg L(-1)). Interferences from transition metal ions were found to be insignificant for determination of the four elements in presence of L: -cysteine. Long-term and short-term stability was also evaluated. The precision, expressed as RSD for 15 replicate measurements was 0.7% for Sb, 1.7% for Sn, 2.5% for V, and 2.3% for Zn at 200 microg L(-1) of each analyte. The detection limits obtained were 0.52, 1.3, 3.2, and 4.7 microg L(-1) for Sb, Sn, V, and Zn, respectively. Spike and recovery experiments were performed on the NIST 1643c trace metals in water standard reference material and results were in agreement with the certified values.

Flow injection analysis with inductively coupled plasma time-of-flight mass spectrometry for the simultaneous determination of elements forming hydrides and its application to urine

The use of an inductively coupled plasma mass spectrometer (ICP-MS) with a time-of-flight (TOF) analyser is illustrated for the simultaneous determination of seven elements forming hydrides (As, Bi, Ge, Hg, Sb, Se and Sn) using flow injection (FI) as the sample introduction system. The chemical conditions for an adequate simultaneous volatile species generation as well as the plasma parameters for simultaneous determination were evaluated. The compromise hydride generation conditions were: 1% NaBH4 and 0.7 M HNO3 final concentration, while an Ar carrier gas flow rate of 1.1 l min−1 provided optimum results for the transport of the volatile species to the ICP-MS. Analytical figures of merit were evaluated under these compromise conditions and compared with those obtained by continuous nebulisation of the same elements in the ICP-MS(TOF). Detection limits in the low pg ml−1 region, linearity over more than five orders of magnitude and repeatability of 2–5% were achieved with the proposed methodology. Application of such a strategy was demonstrated by the simultaneous multi-elemental determination of As, Bi, Ge, Hg, Sb, Se and Sn in spiked urine samples with recoveries better than 80%. For Se, accurate results were only obtained by avoiding volatile species generation, demonstrating the presence of selenium species other than Se(IV) in human urine. The accuracy of the method was also checked by analysing a certified urine sample (NIST SRM 2670) by FI-ICP-MS(TOF) with satisfactory results.

Analysis of Archaeological Ceramics by TXRF and Contrasted with NAA

This paper presents a new alternative analytical tool for determining the composition of archaeological ceramics—total reflection X-ray fluorescence analysis (TXRF). TXRF is a useful technique for the simultaneous determination of elements with atomic number >12. It is a variant of energy dispersive X-ray fluorescence (EDXRF) for the analysis of small samples placed on a flat carrier and it presents the advantage of minimizing matrix effects. The technique has been compared with clay reference material analysed by neutron activation (NAA) in order to test its sensitivity and accuracy for determining the elemental composition of such material. At the current stage of research the technique can produce precise semi-quantitative results with a simple sample preparation process. The semi-quantitative results show that TXRF can be a suitable technique in the multi-elemental characterization of archaeological ceramics, obtaining data useful for archaeological interpretation, which is illustrated by a case study.

Atomic absorption spectrometric determination using a multipurpose dialyser in a flow injection system

A multipurpose dialyser unit was designed and incorporated into the conduits of flow injection (FI) systems and employed for automated dilution and multi-component determinations before detection by atomic absorption spectrometry (AAS). The combined multipurpose dialyser–FI-AAS systems were applied to the determination of copper(II) in industrial effluent samples where there is a great variation in copper(II) concentration levels. Both proposed multipurpose dialyser–FI-AAS systems were suitable to handle the wide variety in concentration levels present in industrial effluent samples. The automated dialyser–dilution system seemed to be ideally suited for the determination of a single element in industrial effluents where the concentration of the element varied considerably in the samples. The advances of the method were further enhanced with the removal of solid particles present in industrial effluents. These particles were of such a nature that they continuously blocked the inlet path to the nebulizer of the AAS detector. The multi-component determination–dialyser system seemed to be ideally suited for the simultaneous determination of elements, which is an advantage for big routine laboratories where there is a pressure on the number of samples and elements to be analysed. The scaling down of sample handling to a sample channelled to various streams and detectors is a further advantage. A prerequisite of the multi-component determination dialyser–FI-AAS system is, however, the number of atomic absorption spectrophotometers required and this may be a disadvantage of this system. The results obtained for copper(II) for both systems at a sampling rate of 120 samples per hour compared favourably with the standard manual atomic absorption spectrometric method. With 75 µl dialysates injected, the relative standard deviation of the draining point with the smallest membrane area was better than 0.3%.

The role of total-reflection X-ray fluorescence in atomic spectroscopy

Total-reflection X-ray fluorescence (TXRF) is a universal and economic method for the simultaneous determination of elements with atomic numbers > 11 down to the lower pg-level. It is a microanalytical tool for the analysis of small sample amounts placed on flat carriers and for contaminations on flat sample surfaces. Analyses of stratified near-surface layers are made possible by varying the incident angle of the primary beam in the region of total-reflection. This non-destructive method is especially suitable for thin layers of a few nanometres, deposited on wafer material although not usable as a microprobe method with a high lateral resolution. Furthermore, depth profiles of biological samples can be recorded by means of microtome sectioning of only a few micrometres, as, for example in the gradient analysis of human organs. In addition to micro- and surface-layer analysis, TXRF is effectively applied to element trace analysis. Homogeneous solutions, for example aqueous solutions, high-purity adds or body fluids, are pipetted onto carriers and, after evaporation, the dry residues are analysed directly down to the pg ml region. Particularly advantageous is the absence of matrix effects, so that an easy calibration can be carried out by adding a single internal standard element. A digestion or separation step preceding the actual determination becomes necessary if a more complex matrix is to be analysed or especially low detection limits have to be reached. A critical evaluation of the recent developments in atomic spectroscopy places TXRF in a leading position. Its outstanding features compete with those of e.g. electrothermal atomic absorption spectrometry (ETAAS), microwave induced plasma optical emission spectroscopy (MIP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) in the field of micro- and trace analysis and with Rutherford backscattering (RBS) and secondary ion mass spectrometry (SIMS) in the surface-layer analysis.

Determination of manganese concentrations in the spinal cords from amyotrophic lateral sclerosis patients by inductively coupled plasma emission spectroscopy

Continuing analytical studies on environmental factors in the foci of amyotrophic lateral sclerosis (ALS) in the Kii Peninsula of Japan and Guam, and metal analysis using neutron activation analysis in central nervous system (CNS) tissues from ALS cases indicate that chronic exposure to metals such as aluminum and manganese, together with a deficiency of minerals such as calcium and magnesium, may play a causative role in the neurodegeneration seen in ALS. An accurate and simple method for detecting minerals and trace metals in small, fresh samples of CNS tissue is necessary in order to follow the pathogenetic behavior of these elements. In this paper, we describe a method for measuring manganese (Mn) content in CNS tissue samples taken from mouse brain using inductively coupled plasma (ICP) spectroscopy and present results of the determination of Mn contents in spinal cord samples from ALS cases using the same method. ICP emission spectroscopy is considered to have great advantage for the simultaneous determination of elements in small, fresh CNS samples because of its simplicity and convenience, and the elimination of the necessity to use potentially dangerous acids. Results showed that the mean concentration of Mn in a mouse brain (0.56 μg/g) and in human spinal cords (0.39 μg/g wet weight in the anterior horn, 0.37 in the lateral fasciculus, 0.39 in the posterior horn and 0.28 in the posterior fasciculus) were compatible with results previously reported using other methods. In ALS spinal cords, the mean content of Mn was similar to that of controls, but the distribution differed. In the ALS cases, Mn contents were higher in the anterior horn and lateral fasciculus than in the posterior horn. A negative correlation between Mn and Ca contents was shown in the control spinal cords, but not in the ALS cords. Mn has been shown to inhibit neurotransmitter release with competitive inhibition of Ca in excitation-secretion coupling. Mn also activates calcium-activated neutral protease (CANP) under a disturbance of Ca metabolism. CANP probably controls the initial steps of intracellular protein degradation. It is speculated that an imbalance between Mn and Ca concentrations in the spinal cords of the ALS case may be associated with functional disability and neuronal death.

Simultaneous determination of elements in soft tissues of the Japanese oyster Crassostrea gigas by PIXE.

Simultaneous determination of elements in soft tissues of the Japanese oyster Crassostrea gigas was carried out. The recently developed method of PIXE was used in this study. The elements determined repeatedly during the experimental period were Cl, S, K, Zn, Ca, Fe, Br, Cu, Sr, Mn, Ni, Se, Ga, Cr and Ti. These can be classified into five groups in the order of elemental quantity. Localities of several elements, such as K, Ca, Mn, Fe, Cu and Zn among five different tissues such as mantle, gill, digestive diverticula, adductor muscle and remainders were compared in three physiological stages of the oyster. The element K showed no significant difference in five kinds of tissue. A typical accumulation was found for Ca in the mantle. A typical pattern was also observed for Mn in the remainders. The patterns were quite similar for Fe, Cu and Zn. The con-centration of Mn, Fe, Cu and Zn in the remainders seems to be decreased as a result of an increase in the remainders weight, while the diminution was not observed for K and Ca. These results sug-gest that the high accumulation occurs as a result of characteristic affinities of elements with specific tissues and organs due to the physiological activity of the oyster, especially for certain stages, concerning glycogen stores and sexual maturation.