Maja Welna

Multi-element analysis, bioavailability and fractionation of herbal tea products

Herbal teas (Mentha piperitae folium and mixture Marticaria chamomilla flos with Lavandula officinalis flos) were compared considering the total contents of micro (Al, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti, V) and macro (C, H, N, S, Ca, Mg, P) elements, bioavailability and fractionation. Different methods (inductively coupled plasma optical emission spectrometry (ICP OES), Fourier transform infrared spectroscopy (FTIR) and CHNS elemental analysis) were applied. The microwave-assisted digestion procedure was found to be more effective than the hot-plate heating for the wet acid digestion of tea. The application of the modified BCR (Community Bureau of Reference) sequential extraction procedure exhibited differences in the concentrations of metal bound to reducible and oxidizable fractions. The accuracy of method was verified by analysis of certified reference material INCT-TL-1 Tea Leaves. The daily intake of all elements from the analyzed herbal tea infusion did not exceed the maximum permissible levels and does not constitute health risk.

Evaluation of a simple and fast method for the multi-elemental analysis in commercial fruit juice samples using atomic emission spectrometry

Four sample preparation procedures: wet digestion with HNO3/H2O2 (P1), 1:1 dilution with 2% HNO3 and latter centrifugation (P2) or filtration (P3) and direct analysis after centrifugation (P4) for the determination of total Al, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, P, Pb, Sr and Zn in fruit juices by inductively coupled plasma atomic emission spectrometry (ICP OES) were compared. Precision (RSD), accuracy (by standard addition or recovery) and limit of detection (LOD) were used to evaluate characteristics of the procedures. Dilution with 2% HNO3 and centrifugation (P2) provided the best results, i.e. LODs between 0.11 and 108 ng mL(-1), RSDs of 1% and 5% and accuracy better than 5%. This procedure was also simple, fast and could be applied for routine analysis. Element concentrations agreed with those after wet digestion, therefore the procedure can be alternatively used instead of conventional sample treatment. Several commercial juices were analysed with this procedure.

Effect of sample preparation procedure for the determination of As, Sb and Se in fruit juices by HG-ICP-OES

Various sample preparation procedures for the simultaneous determination of As, Sb and Se in fruit juices by hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP-OES) were examined. Applicability of total wet digestion with HNO3/H2O2, partial decomposition (solubilisation in aqua regia), 1:1 dilution with 2% (v/v) HNO3 and direct analysis were evaluated. Hydrides were generated in the reaction of an acidified sample with NaBH4 after pre-reduction with KI-ascorbic acid for total As and Sb, and boiling with HCl for total Se. Best results, i.e. limits of detection (LODs) of 0.51-0.73 ng mL(-1), precision (RSD) within 1.7-3.6% and recoveries for spiked samples between 101% and 106% were found using aqua regia treatment. This procedure simplifying and improving sample preparation step prior to As, Sb and Se measurements in fruit juices by HG-ICP-OES, thus could be adequate for the routine analysis in terms of the quality control of these drinks.

The determination of elements in herbal teas and medicinal plant formulations and their tisanes

Elemental analysis of herbal teas and their tisanes is aimed at assessing their quality and safety in reference to specific food safety regulations and evaluating their nutritional value. This survey is dedicated to atomic spectroscopy and mass spectrometry element detection methods and sample preparation procedures used in elemental analysis of herbal teas and medicinal plant formulations. Referring to original works from the last 15 years, particular attention has been paid to tisane preparation, sample matrix decomposition, calibration and quality assurance of results in elemental analysis of herbal teas by different atomic and mass spectrometry methods. In addition, possible sources of elements in herbal teas and medicinal plant formulations have been discussed.

Investigation of Simultaneous Generation of Arsenic, Bismuth and Antimony Hydrides Using Inductively Coupled Plasma Optical Emission Spectrometry

Hydride generation from solution containing As(III), Bi(III), and Sb(III) by means of different borane reductants and acids using inductively coupled plasma optical emission spectrometry as a detection system was investigated. The As, Bi, Sb, B, C, H, and N lines as well as the OH and CN molecules were recorded. Their intensities in relation to hydride formation conditions were measured. Effects of the HCl, CH3COOH, and C6H8O7 acids as well as the NaBH4, H3B-NH(CH3)2, and H3B-NH2C(CH3)3 reductants on efficiency of the As, Sb, and Bi hydride generation were investigated and discussed. Influence of hydride generation conditions on plasma was studied.

Speciation and Fractionation of Elements in Tea Infusions

Elements in tea infusions may be present in the form of various species with different mobility, availability, and biological activity. As a result, actual impact of the consumption of this beverage on human health cannot be anticipated on the basis of measurements of total concentrations of elements. Nevertheless, this type of the elemental analysis is generally found in the relevant literature and its results are used to judge the safety of tea according to accepted health and nutrition standards or estimate the coverage of recommended daily allowances for elements. Such an approach is not entirely justified because the bioaccessibility and bioavailability of elements from tea can be dependent on their ultimate speciation forms. The need for reliable information on the functional speciation of elements present in tea, the most popular beverage in everyday life, is obvious in terms of the comprehension of the nutritional value and safety of tea. This review article covers the topic of the speciation and fractionation of elements in tea. It discusses the relationship of different forms of elements with their leachability, bioavailability, and actual uptake. Analytical approaches to the speciation and fractionation analysis are presented.

Influence of chemical vapor generation conditions on spectroscopic and analytical characteristics of a hyphenated CVG-ICP system

Excitation conditions of inductively coupled plasma hyphenated with chemical vapor generation with the use of borane reducing agents (NaBH4, C(CH3)3NH2–BH3 and (CH3)2NH–BH3) and acids (HCl and CH3COOH) were investigated. The electron number density, the Mg II/Mg I intensity ratio as well as the Ar, B, Bi, Sb and H excitation temperatures were measured at various concentrations of the reductants and acids. Some analytical figures of merit were also determined. The plasma parameters were affected if NaBH4 was applied. Influence of other borane reductants was not so significant. Hydrogen produced due to chemical vapor generation was responsible for changes in the ICP characteristics, while a role of other products transported simultaneously to plasma was negligible. The Ar, B, Bi and Sb excitation temperatures were independent or slightly dependent on chemical vapor generation conditions. The electron number density increased with NaBH4 concentration, from 0.7 × 1015 cm−3 for “dry” argon plasma to 1.5 × 1015 cm−3 while the Mg II/Mg I intensity ratio varied from 5 to 11. At low concentrations of the reductants and acids, the plasma was not in robust conditions. If the NaBH4 was the reductant, the H temperature varied more significantly, from 3100 to 2100 K.

Quality of the Trace Element Analysis: Sample Preparation Steps

Current status of elemental analysis performed using atomic spectroscopy techniques is to reach the best results in the shortest time and with minimal contamination and reagent consumption. Various spectroscopic methods such as flameand graphite furnace atomic absorption spectrometry (Fand GF-AAS), inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS) have been used for many years for determination of elements, since they met needs required in analytical applications. Constant progress in detector technology can still been observed, e.g. in terms of lowering quantification limits. Despite these advantages, quality of results does not follow the same tendency and sample preparation is recognized to be a critical point and the most important error source in modern analytical method development. This is especially true for solid samples that have to be brought into solution before measurements. It is dictated by instrumentation requirements dedicated to analysis of liquid samples. Determination of analyte concentrations in solid materials is not an easy task and several factors should be considered in order to minimize uncertainty in sample preparation and to achieve real objectives of analysis. It includes sample type and its matrix composition responsible mainly for the degree of difficulties during sample preparation and analyte determination. Therefore, the good choice of sample treatment and confidence of its application become a key ensuring to obtain reliable results.

Optimization of Sample Preparation of Carrot-Fruit Juice for Determination of Antimony, Arsenic, and Selenium by Hydride Generation-Inductively Coupled Plasma Optical Emission Spectrometry

Sample preparation procedures for the determination of As, Sb, and Se in carrot-fruit juice by hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP OES) were examined. The applicability of a partial decomposition using aqua regia and simple dilution with a 2% (v/v) HNO3 solution were tested and compared to a traditional treatment based on the wet digestion with a HNO3/H2O2 mixture. The pre-reduction and hydride generation reaction conditions were evaluated. Under the optimal conditions, the hydrides were produced in the reaction of an acidified sample with NaBH4 after pre-reduction with ascorbic acid [0.5% (m/v)] and KI [0.5% (m/v)] in 3 mol L−1 HCl for total As and Sb, and boiling with HCl (6 mol L−1) for total Se. The best results were obtained for the aqua regia procedure, resulting in limits of detection (LODs) between 1.2–2.4 ng g−1 in the samples and recoveries from 90.9% to 109.1%. The method was successfully applied (without matrix effects) for the determination of As in dense mousse and pulp juice samples and for Sb in pulp juices. Standard solutions, processed in the same way as samples, were used for the calibration. Undecomposed matrix constituents strongly influenced Se; hence this element was determined using the method of standard addition. Concentrations of studied elements in analyzed products were at the trace level, that is, 6–32 ng g−1, 4–10 ng g−1, and 4–13 ng g−1 for Se, As, and Sb, respectively.

Improvement of a sample preparation procedure for multi-elemental determination in Brazil nuts by ICP-OES

Various sample preparation procedures, such as common wet digestions and alternatives based on solubilisation in aqua regia or tetramethyl ammonium hydroxide, were compared for the determination of the total Ba, Ca, Cr, Cd, Cu, Fe, Mg, Mn, Ni, P, Pb, Se, Sr and Zn contents in Brazil nuts using inductively coupled plasma optical emission spectrometry (ICP-OES). For measurement of Se, a hydride generation technique was used. The performance of these procedures was measured in terms of precision, accuracy and limits of detection of the elements. It was found that solubilisation in aqua regia gave the best results, i.e. limits of detection from 0.60 to 41.9 ng ml−1, precision of 1.0–3.9% and accuracy better than 5%. External calibration with simple standard solutions could be applied for the analysis. The proposed procedure is simple, reduces sample handling, and minimises the time and reagent consumption. Thus, this can be a vital alternative to traditional sample treatment approaches based on the total digestion with concentrated reagents. A phenomenon resulting from levels of Ba, Se and Sr in Brazil nuts was also discussed. Graphical Abstract