Total Reflection X-ray Fluorescence Analysis Research Articles

Quantification of [99Tc]TcO4- in urine by means of anion-exchange chromatography–aerosol desolvation nebulization–inductively coupled plasma–mass spectrometry

To sensitively determine 99Tc, a new method for internal quantification of its most common and stable species, [99Tc]TcO4-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{O}}_{4}^{-}$$\\end{document}, was developed. Anion-exchange chromatography (IC) was coupled to inductively coupled plasma–mass spectrometry (ICP-MS) and equipped with an aerosol desolvation system to provide enhanced detection power. Due to a lack of commercial Tc standards, an isotope dilution-like approach using a Ru spike and called isobaric dilution analysis (IBDA) was used for internal quantification of 99Tc. This approach required knowledge of the sensitivities of 99Ru and 99Tc in ICP-MS. The latter was determined using an in-house prepared standard manufactured from decayed medical 99mTc-generator eluates. This standard was cleaned and preconcentrated using extraction chromatography with TEVA resin and quantified via total reflection X-ray fluorescence (TXRF) analysis. IC coupled to ICP-MS enabled to separate, detect and quantify [99Tc]TcO4-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{O}}_{4}^{-}$$\\end{document} as most stable Tc species in complex environments, which was demonstrated in a proof of concept. We quantified this species in untreated and undiluted raw urine collected from a patient, who previously underwent scintigraphy with a 99mTc-tracer, and determined a concentration of 19.6 ± 0.5 ng L−1. The developed method has a high utility to characterize a range of Tc-based radiopharmaceuticals, to determine concentrations, purity, and degradation products in complex samples without the need to assess activity parameters of 99(m)Tc.Graphical

Evaluations of the optimal plasma treated area in total reflection X-ray fluorescence analysis and the retention period of superhydrophilic ability of the substrate

An atmospheric pressure plasma jet was applied to control the form of a dried residue for total reflection X-ray fluorescence analysis.

Titanium dioxide release behavior during wash of UV-protective garments by total reflection X-ray fluorescence

The increasing worldwide use of different kinds of clothes with ultraviolet protection in recent years, in particular employing titanium dioxide nanoparticles, is driving the researchers’ attention to the possible environmental problems due to titanium release. This study aims at determining the amount of titanium released from seven ultraviolet-protective garments into the wash water employing total reflection X-ray fluorescence spectrometry. For this, a wash protocol was designed based on the international standard ISO 105-C06:2010 and the literature. Pieces (4 cm × 10 cm) of textile were sampled from the garments and submitted 30 times to the wash protocol. The wash water produced in each wash was then prepared for total reflection X-ray fluorescence analysis. Results showed that the titanium released in 30 washes was between 8.6 ± 1.3 µg/L and 168 ± 3 µg/L. Every sample released titanium in the first to third wash, except sample 1, which first released titanium in the 18th wash. The greatest titanium release in one single wash was also the 18th wash of sample 1, which released 77 ± 2 µg/L. These results showed the good performance of total reflection X-ray fluorescence spectrometry in quantifying low titanium amounts in wash water, which is a hard task even for well-established analytical methods.

Are Twin Pregnancies at Higher Risk for Iron and Calcium Deficiency than Singleton Pregnancies?

The aim of this study was to compare the iron and calcium status in singleton and twin pregnancies and to assess whether there is an increased risk for iron and calcium deficiency in twin gestation. The study included 105 singleton and 9 twin pregnancies at or above 35 weeks of gestation. Information on prenatal supplementation with iron or calcium was acquired, and adverse perinatal outcomes were recorded. Biosamples from all 114 mothers and 73 newborns (61 singleton and 12 twin newborns) were finally analyzed. Total iron and calcium concentrations in serum were measured through total reflection X-ray fluorescence analysis. The results indicated no significant differences in maternal serum iron and calcium concentrations between singleton and twin pregnancies. Similarly, iron and calcium concentrations in newborn umbilical cord serum samples were not different between singleton and twin pregnancies. The comparison of total iron and calcium between mothers and umbilical cord serum indicated significantly lower concentrations in the mothers, with the differences being not homogenous but rather pair-specific. A significant positive correlation between maternal serum and umbilical cord serum calcium concentration was noticed. Prenatal iron supplementation was associated with higher iron concentrations in both mothers and newborns, supporting the efficiency of supplementation and the quality of the study methods. Collectively, the data indicate no significant differences in serum iron and calcium concentrations with regard to singleton or twin pregnancies and the efficiency of iron supplementation during pregnancy for increasing iron status.

New quantification approaches for total-reflection X-ray fluorescence analysis of micro-sized samples: Apatite case study

Sensitive methods for quantitative elemental analysis of micro-sized samples are limited. In this study, total-reflection X-ray fluorescence (TXRF) method was applied as fast and cost-efficient method to apatite microcrystals. In situ acid digestion based on direct treatment of single crystal onto the carrier was used as sample preparation strategy. Since the internal standard addition is complicated in the case of micro-sized samples, new quantification approaches based on external calibration for TXRF analysis of apatite were offered. An experimental design was created for apatite samples with a differentiation of specimen masses from 1.0 to 100 μg to find patterns in the spectral information. A workflow has been proposed for analyzing apatite crystals of various sizes (100, 500, 1000 µm) with TXRF based on an external calibration using an apatite powder sample as a standard and normalizing the spectra to the P-Kα and Mo-Kα peaks. The conditions of the workflow should be the following: Ca/P ratio is in a range between 19 and 23, and a dead time value does not exceed 4.0 %. The dead time value was used as a main factor of quantification, when calibration sample should match the unknown sample. Limit of detection values of the proposed method are from 1.0 to 100 μg/g depending on the crystal size and element of interest. Validation of the TXRF method was performed by analysis of Durango and McClure apatite samples. Comparison of TXRF results with laser ablation inductively coupled plasma mass spectrometry data showed the good agreement between two methods.

High-accuracy total reflection X-ray fluorescence analysis for determining trace elements using substrate cleaned by ammonia-hydrogen peroxide mixture

Total reflection X-ray fluorescence (TXRF) analysis is one of the useful techniques for determining trace elements. Owing to the high detection sensitivity of X-ray fluorescence in small residues, the hydrophobic substrates are generally used to form dot-type residue. However, when measuring low-Z elements in sample solutions with high concentrations of matrix elements, obtaining sufficient measurement sensitivity can be difficult. X-ray fluorescence is absorbed by the matrix elements, which means that the absorption effect increases in the thicker dried residue compared to the thinner dried residue. To avoid this absorption effect, we have proposed a thin film-type residue. In this study, the glass substrate was treated with an ammonia-hydrogen peroxide mixture (APM). The hydrogen peroxide decomposes organic components, and ammonia slightly etches glass materials. The APM-treated region was limited to a diameter of 6 mm by using a polytetrafluoroethylene mask placed on the glass substrate. As a result, the surface is refreshed to expose the hydroxyl group to make it superhydrophilic. The measured contact angle was 5°. By using the APM-treated superhydrophilic substrate to prepare dried residue, the net intensities in low Z elements were improved. The ratio of Al Kα intensity, calculated as net intensity in the APM-treated substrate divided by it in the hydrophobic substrate, was 2.29. The recovery of each element in the APM-treated substrate was almost 100%; however, recoveries of elements (Al, P, K, and Ca) in the hydrophobic substrate showed significant deviations from 100% (the recovery of Al was approximately 32%). In summary, we successfully improved both analytical sensitivity and accuracy in TXRF analysis by using the APM treated substrate.

Chelate complexed multi-elemental printing performance of a small and cost efficient picoliter droplet printing device for micro preparation

We introduce an inexpensive modular picoliter pipetting device using modified commercially available thermal inkjet cartridges. The system is capable of reliable deposition of 65 elements. The printing solutions were modified to prevent the dissolution of Ni from the nozzle head, keeping those at a pH of >9. Loss of cations to the glass surfaces inside the nozzle head is prevented by forming anionic complexes with ethylenediaminetetraacetic acid in basic conditions. For some elements, e.g., Si, additives like tetramethylammonium hydroxide are necessary.The volumes of the droplets were obtained, weighing 30,000–360,000 droplets ejected by the printer using a laboratory scale. The droplet volume was within a range of 142–184 pL, depending on the formulation. The delivered elemental masses and the reproducibility were determined using total reflection X-ray fluorescence analysis and inductively coupled plasma optical emission spectrometry. Delivered masses were in the range of 0.98 pg – 11.9 pg per element and droplet.The shape of deposits of about 31 pg per element was studied using atomic force microscopy, optical microscopy, and confocal laser scanning microscopy. They were mostly spherical and ca. 14 μm in diameter and ca. 2 μm in height. The broad range of printable elements allows for the micro preparation of solid compounds for establishing a grazing incidence X-ray diffraction analysis library. As an example, the MgAl2O4 spinel was synthesized by printing of the formulation and subsequent calcination. Here we show its performance for the preparation of minerals in the context of recycling of critical elements from pyrometallurgical slags.

Development of Sample Preparation Methods for Vitamin-Mineral Complexes and Determination of their Elemental Composition Using Total Reflection X-Ray Fluorescence Analysis

Development of Sample Preparation Methods for Vitamin-Mineral Complexes and Determination of their Elemental Composition Using Total Reflection X-Ray Fluorescence Analysis

Rapid Water Quality Analysis by Total Reflection X-ray Fluorescence Analysis

Rapid Water Quality Analysis by Total Reflection X-ray Fluorescence Analysis

Improvement of suspension-assisted total reflection X-ray fluorescence analysis of ores using wet grinding and empirical calibrations

In this study, the suspension-assisted total-reflection X-ray fluorescence analysis of ores was improved using the wet grinding procedure to produce ultra-fine suspended powder mixed with internal standard solution in aqueous media. The advantages of the proposed technique were demonstrated by the example of the determination of S, Fe, Ni, and Cu in sulfide copper‑nickel ores containing various ratios of sulfide and silicate minerals. We showed that the powerful mixing of 100 mg of ore powder and 4 mL of ultra-pure water as a dispersing medium with 20 g of grinding balls of 1 mm in diameter leads to the preparation of homogeneous suspension with monomodal particle size distribution having 90% of the particle size <6 μm. The suspension after wet grinding was diluted up to 50 mL with ultra-pure water to obtain a final concentration of the suspended powder of 2 mg/mL. Relative precision of the described sample preparation technique calculated from duplicate pairs of suspensions was 16% for S, 9% for Fe, 15% for Ni and 10% for Cu. Three spectral data processing techniques were further compared with respect to the quantification accuracy of target elements: internal standard, univariate and multivariate regressions. It was shown that the two latter methods can be used to improve the trueness of the internal standard method, especially for Cu and Fe.

Synthesis of Trimetallic (Ni-Cu)@Ag Core@Shell Nanoparticles without Stabilizing Materials for Antibacterial Applications.

We report a simple method to prepare colloidal trimetallic (Ni-Cu)@Ag core@shell nanoparticles (NPs) without stabilizing materials. Experimental evidence was found for the successful synthesis of these NPs using X-ray diffraction (XRD), optical spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The presence of core metals (Ni and Cu) was confirmed by elemental analysis using a total reflection X-ray fluorescence (TXRF) analysis. In addition, the absorption spectra of the prepared samples exhibited broad bands compared to the bands of the monometallic NPs, indicating the formation of a core–shell nanostructure. The antibacterial activity of the trimetallic NPs was evaluated against three Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Salmonella) and two Gram-positive (Streptococcus and Staphylococcus aureus) bacteria on Mueller–Hinton agar. These NPs showed high inhibition of bacterial growth at the low sample concentrations used in this study compared to other nanomaterials. One of the interesting results of the current study is that the inhibition zone of Pseudomonas aeruginosa as a resistant bacterium was high for most NPs. These results make the prepared samples promising candidates for antibiotic material applications.

Determination of Impurities in Graphite Using Proton Induced Gamma Ray Emission, Total Reflection X-ray Fluorescence and Instrumental Neutron Activation Analysis

Determination of impurities in graphite is very important for its quality control, as their presence even at trace level can affect the performance of graphite in various applications. Graphite with equivalent boron content (EBC) less than 5 mg kg-1 is considered as nuclear grade. Elements with high neutron absorption cross section (boron and rare earths) contribute significantly to EBC. Non-destructive method is preferred as there is no sample processing and probability of loss of volatile elements while digestion. Proton Induced Gamma Ray Emission (PIGE), Instrumental Neutron Activation Analysis (INAA) were utilized for the non- destructive determination of impurities in both nuclear and commercial grade graphite. Low Z elements like Li, B, F, Na, Al and Si were detected in graphite by PIGE whereas Na, K, Sc, Cr, Mn, Fe, Co, Zn, Rb, Zr, Sb, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb, Hf, Ta, Th were determined using INAA. Few elements like Ca, Ti, V, Ni, Sr and Pb remained undetected by both the non-destructive techniques. These elements were determined by Total Reflection X-ray Fluorescence (TXRF) after digestion of the graphite samples by dry ashing. Combinations of these techniques were utilized to get maximum information regarding the impurities present in graphite.

Direct digestion of human scalp hair on the substrate used for total reflection X-ray fluorescence analysis.

It is important to determine the elemental content of scalp hair to evaluate human health and environmental contamination. Here, a new sample preparation method for total reflection X-ray fluorescence analysis was developed by directly digesting the human hair on the sample holder. A human hair sample was subjected to thermal nitric acid treatment for sample digestion and homogenization. The Zn concentration was estimated to be ~ 1.89 × 102μg/g. We can evaluate other elements of human hair by using this method.

Total Reflection X-ray Fluorescence Analysis of Plasma Elements in Autistic Children from India.

Trace elements are essential for the human body's various physiological processes but if they are present in higher concentration, these elements turn to be toxic and cause adverse effect on physiological processes. Similarly, deficiency of these essential elements also affects physiological processes and leads to abnormal metabolic activities. There is a lot of interest in recent years to know the mystery behind the involvement of trace elements in the metabolic activities of autistic children suspecting that it may be a risk factor in the aetiology of autism. The present study aims to analyse the plasma trace elements in autistic children using the total reflection X-ray fluorescence (TXRF) technique. Plasma samples from 70 autistic children (mean age: 11.5 ± 3.1) were analysed with 70 age- and sex-matched healthy children as controls (mean age: 12 ± 2.5). TXRF analysis revealed the higher concentration of copper (1227.8 ± 17.8), chromium (7.1 ± 2.5), bromine (2695.1 ± 24) and arsenic (126.3 ± 10) and lower concentration of potassium (440.1 ± 25), iron (1039.6 ± 28), zinc (635.7 ± 21), selenium (52.3 ± 8.5), rubidium (1528.9 ± 28) and molybdenum (162,800.8 ± 14) elements in the plasma of autistic children in comparison to healthy controls. Findings of the first study from India suggest these altered concentrations in elements in autistic children over normal healthy children affect the physiological processes and metabolism. Further studies are needed to clarify the association between the altered element concentration and physiology of autism in the North Karnataka population in India.

Written in ink: Elemental signatures in octopus ink successfully trace geographical origin

In recent years, validation of seafood authenticity and provenance has attracted the attention of authorities and consumers. Increasing levels of food fraud has raised awareness regarding seafood traceability, especially in highly valuable and highly consumed seafood products, such as the common octopus (Octopus vulgaris). Seafood traceability studies based on trace element fingerprinting generally focus on muscle tissues or carbonate structures whilst the ink fluid has been overlooked. Untargeted multi-element Total Reflection X-ray Fluorescence (TXRF) analysis of O. vulgaris ink successfully discriminated four collection areas [91.2 % and 84.1 % using Variable Importance in Projection Partial Least-Squares Discriminant Analysis (VIP-PLS-DA) and Linear Discriminant Analysis (LDA), respectively] along the mainland Portuguese coast (ca. 900 km coast in the Northeast Atlantic). Arsenic, Pb, Na, Sr and Rb were highlighted as elements with higher contributions for sample discrimination between the four considered capture areas. Regarding food safety, it is important to note that some ink samples Cu, Mn and Pb concentrations exceeded human consumption recommended values. Thus, the results show that untargeted TXRF spectroscopy analysis of O. vulgaris ink is a reliable tool for disentangling the geographical origin of the octopus, as well as to inform about the food safety of octopus ink.

Elemental fingerprinting of thornback ray (Raja clavata) muscle tissue as a tracer for provenance and food safety assessment

The verification of food authenticity and provenance is a complex task and has raised public concern in recent years due to multiple episodes of food fraud and potential risks to consumers. In this sense, the evaluation of multi-elemental signatures is increasingly applied to confirm and validate the site of origin of animal products. Yet, we lack understanding of its efficacy for mobile organisms such as fish. Using multi-element Total Reflection X-ray Fluorescence (TXRF) analysis of muscle of thornback ray Raja clavata we successfully identified the fishing area of individuals collected in four areas along the Portuguese Atlantic coast (Atlantic Iberian waters, Northeast Atlantic). Overall, As, Fe, Sn, V and Zn presented higher contributions to discrimination (especially Fe and Rb for neighbouring collection areas), whilst the higher concentration elements (Na, K, P, S, Ca, Cl, Br and Sr) had similar concentrations among locations. Rays captured in the two areas with higher urbanization/industrialization presented higher concentration of elements associated with anthropogenic activities (such as As, Zn, Sn and V). In terms of food safety, only 0.9% and 2.8% of the individuals surpassed the recommended thresholds values for human consumption for Hg and Cd respectively. A canonical analysis of principal components resulted in classification accuracy of thornback ray to collection site of 56.7–84.2% (depending on site), with an overall accuracy of 65.1% over c. 500 km of coast in the Northeast Atlantic.

High-accuracy determination of trace elements by total reflection X-ray fluorescence spectrometry using freeze-dried specimens.

Total reflection X-ray fluorescence (TXRF) analysis is conducted to determine trace elements in a sample solution, which is dropped onto a substrate and dried. Therefore, the form of the residue affects the quantitative results. The absorption of X-ray fluorescence (XRF) follows the Lambert-Beer law; the absorption effect of XRF in a thick residue (dotted-type residue) is stronger than that in a thin residue (film-type residue). The absorption effect is particularly remarkable during the determination of low-Z elements in a high-elemental concentration solution. In this study, we propose a new film-like-residue preparation process based on the freeze-drying method to obtain accurate TXRF results. The sample solution is dropped onto the substrate and inserted into a chamber. The chamber is cooled using liquid nitrogen; resultantly, an aliquot of the sample is frozen. The chamber is depressurized using a vacuum pump, and the freeze-dried residue is prepared by maintaining the chamber at room temperature. To evaluate the efficiency of the freeze-drying-based method for sample preparation for TXRF analysis, we prepare a multi-element solution containing high-elemental concentration components. For the residue prepared using the freeze-drying method, the relative standard deviations of the quantitative values and the minimum detection limits are improved because the absorption effect is weakened. The sample preparation process based on the freeze-drying method facilitates accurate TXRF analysis of high-elemental concentration solutions and can be applied for the analysis of trace elements in different types of solutions such as environmental water and wastewater.

Development of a certified reference material (CRM) for seven trace elements (Al, Ca, Fe, K, Mg, Na and Ti) in high purity quartz

Certified reference material (CRM) for trace elements in quartz matrix is required to assess the performance of analytical methods in regards to their validation, calibration and for comparability of measurements between laboratories. Due to unavailability of matrix matched CRMs in our country, National Centre for Compositional Characterization of Materials (NCCCM) of Bhabha Atomic Research Centre (BARC), Hyderabad and Council of Scientific and Industrial Research CSIR-National Physical Laboratory (NPL), New Delhi have initiated a program for the production of a CRM for the certification of critical trace elements in high purity quartz. Preparation and certification of Indian Reference Material (BND 4101.01), quartz powder with certified mass fractions of seven trace impurities was carried out jointly between NCCCM and NPL; two national laboratories of Government of India. Sampling constant (Ks) were established before carrying out the homogeneity test within and between bottles. The homogeneity test was carried out by NCCCM. The certified values were assigned after Inter Laboratory Comparison Exercise (ILCE) between reputed National Laboratories in India as per ISO-Guide 34 & 35. Analytical techniques like Inductively coupled plasma atomic emission spectrometry (ICP-AES), Flame atomic absorption spectrometry (FAAS) and Total reflection x-ray fluorescence analysis (TXRF) have been used for the characterization of property values.

Predicting neurological recovery after traumatic spinal cord injury by time-resolved analysis of monocyte subsets.

Monocytes and lymphocytes elicit crucial activities for the regenerative processes after various types of injury. The survival of neurons exposed to mechanical and oxidative stress after traumatic spinal cord injury depends on a multitude of factors. In this study, we sought to evaluate a correlation between remission after traumatic spinal cord injury and the dynamics of monocyte subsets in respect to the lymphocytes' responsive potential, cytokine expression, patterns of trace element concentration and clinical covariates. We examined prospectively 18 (three female, 15 male) patients after traumatic spinal cord injury. Blood samples were drawn at admission and 4 h, 9 h, 12 h, 1 and 3 days as well as 1 and 2 weeks and 1, 2 and 3 months after the trauma. Analysis of cytokines (CCL2, IL-10, enolase 2, CXCL12, TGF-β1, TGF-β2) was performed using a multiplex cytokine panel. Plasma trace element concentrations of selenium, copper and zinc were determined by total reflection X-ray fluorescence analysis; neopterin, selenoprotein P (SELENOP) and ceruloplasmin (CP) by enzyme-linked immunosorbent assay; and selenium binding protein 1 (SELENBP1) by luminometric immunoassay. The responsive potential of lymphocytes was assessed using transformation tests. The monocyte subsets (classical, intermediate, and non-classical) and expression of CD14, CD16, CXCR4 and intracellular IL-10 were identified using a multi-colour flow cytometry analysis. The dynamics of the cluster of intermediate CD14-/CD16+/IL10+/CXCR4int monocytes differed significantly between patients with an absence of neurological remission (G0) from those with an improvement (G1) by 1 or 2 American Spinal Injury Association Impairment Scale (AIS) steps (Kruskal-Wallis Test, P = 0.010, G0 < G1, AIS+: 1 < G1, AIS+: 2) in the first 24 h. These dynamics were associated inversely with an increase in enolase and SELENBP1 14 days after the injury. In the elastic net regularized model, we identified an association between the increase of a subpopulation of intermediate CD14-/CD16+/IL10+/CXCR4int monocytes and exacerbated immune response within 24 h after the injury. These findings were reflected in the consistently elevated response to mitogen stimulation of the lymphocytes of patients with significant neurological remission. Early elevated concentrations of CD14-/CD16+/IL10+/CXCR4int monocytes were related to higher odds of CNS regeneration and enhanced neurological remission. The cluster dynamics of CD14-/CD16+/IL10+/CXCR4int monocytes in the early-acute phase after the injury revealed a maximum of prognostic information regarding neurological remission (mean parameter estimate: 0.207; selection count: 818/1000 repetitions). We conclude that early dynamics in monocyte subsets allow a good prediction of recovery from traumatic spinal cord injury.

Determination of essential elements (Mn, Fe, Cu and Zn) in herbal teas by TXRF, FAAS and ICP‐OES

The aim of this study was the comparison of the results obtained in the determination of the content of essential elements such as Mn, Fe, Cu and Zn in vegetation samples using different analytical approaches, including suspension preparation and total reflection X‐ray fluorescence (TXRF) analysis as well as most commonly used spectroscopic methods in the field of vegetal analysis such as acid digestion in combination with atomic emission (AES) and atomic absorption spectrometry (AAS). In the case of TXRF analysis, two instruments equipped with different X‐ray tubes anodes (W and Mo) were used to better evaluate the potential of TXRF for vegetal samples analysis. Analytical figures of merit for the considered methods were determined by the analysis of plant reference materials. The one‐way analysis of variance (ANOVA) applied to the analysed and certified values showed that the results were not statistically different at the significance level of p‐values &lt;0.05. Therefore, suspension preparation and TXRF analysis proved to be a sustainable and fast analytical alternative to the most commonly used ones involving a previous digestion of the sample and inductively coupled plasma optical emission spectrometry (ICP‐OES) or flame atomic absorption spectrometry (FAAS) analysis. Finally, the different analytical approaches were applied to the determination of Mn, Fe, Cu and Zn in a set of herbal teas used for medical purposes.