Trace Elements In Tea Research Articles

Trace elements in tea in Ouargla, Algeria and health risk assessment

ABSTRACT Tea is one of the most common drinks, consumed for its pleasant flavour and several medicinal values. The present study aimed to determine the levels of trace elements in tea products marketed in the Saharan region of Ouargla, Algeria and to evaluate the health risks associated with its regular consumption in adults and infants. To this aim, 78 tea samples were analysed by Inductively Coupled Plasma – Mass Spectrometry. Tea samples appeared to be contaminated by lead (0.73 ± 0.08 µg g−1) and aluminium (0.22 ± 0.02 µg g−1). Cadmium, arsenic, mercury, cobalt, manganese, nickel, chromium, zinc and copper were also detected. General linear model analysis indicated that black tea samples were the most contaminated. Tea samples packed in tea bags were the most contaminated with arsenic, aluminium and manganese. The hazard index was 0.28 and 1.33 for adults and for infants, respectively, indicating adverse non-carcinogenic effects in infants.

Health Risk Assessment of Exposure to Trace Elements from Drinking Black and Green Tea Marketed in Three Countries.

Although tea can be beneficial for our health, consuming excess trace elements in tea can be harmful. In this study, the carcinogenic and noncarcinogenic health risk for trace elements in tea influenced by the country of origin, tea type, and infusion process was assessed. Tea (Camellia sinensis) purchased from China, India, and the USA, including black and green tea, were analyzed for essential micronutrients (Cu, Se, and Zn) and nonessential trace elements (Ag, As, Ba, Cd, Cr, and Pb) in leaves and three types of infusions. The results showed that country of origin, tea type, and infusion process had a significant influence on the trace element contents in tea leaves and infusions, also on health risk. Country of origin had a significant influence on Ba, Cr, Pb, and Zn contents in tea leaves and on As, Ba, Cd, Cr, Pb, and Zn contents in tea infusions. Black tea had significantly higher (p < 0.05) Cr and Cu content in tea leaves than green tea, but only Cr content was significantly higher (p < 0.05) than that of green tea in tea infusion. The trace element contents were the highest in the first infusion and decreased as the number of infusion steps increased. The results showed that the consumption of tea infusion was not likely to cause noncarcinogenic risk. However, the carcinogenic risk for As was of concern. Our results indicate that avoiding drinking the first infusion can help to reduce both carcinogenic and noncarcinogenic health risks for trace elements.

Development of a method for the sequential determination of cadmium and chromium from the same sample aliquot of yerba mate using high-resolution continuum source graphite furnace atomic absorption spectrometry

A simple, fast and sensitive method for the sequential determination of cadmium and chromium from the same sample aliquot of yerba mate and leaves of yerba mate is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis. The measures were made using the analytical line at 228.802nm for cadmium and 357.869nm for chromium, and three pixels each for evaluation. The reference material NCS ZC73014 (trace elements in tea) has been analyzed and the results were in agreement with the certified values. A characteristic mass of 0.37pg and 2.4pg was obtained for cadmium and chromium, respectively. The limits of detection were 0.25ng for cadmium and 0.72ng for chromium, and the precision, expressed as relative standard deviation, was around 10%. Thirteen commercial samples and five leave samples were analyzed and the concentration of cadmium varied between 0.28 and 2.06μgg−1 and that of chromium between 0.27 and 2.37μgg−1. The process of infusion preparation resulted in a leaching of around 25% for cadmium and 60% for chromium.

Determination of silicon in plant materials using direct solid sample analysis with high-resolution continuum source graphite furnace atomic absorption spectrometry

In this work, a method for the determination of silicon in plant material by high-resolution continuum source graphite furnace atomic absorption spectrometry has been developed using direct solid sample analysis. The performance of iridium and rhodium as permanent modifiers alone and combined with the palladium–magnesium modifier in solution was investigated. According to the results, among the investigated modifiers, an improvement in sensitivity and Si signal profile was obtained using 300μg of Rh in combination with 20μg of Pd+12μg of Mg. The optimized pyrolysis and atomization temperatures were 1200 and 2650°C, respectively. Due to the high content of Si in most of the evaluated samples, the analytical line of 221.174nm was chosen. Moreover, an adequate working range (30 to 600ng Si) was achieved after using a minimum gas flow in the atomization stage and the integrated absorbance of the center pixel only. The sample mass varied between 0.03 and 0.50mg, and no spectral interferences were encountered. The limit of detection was 5ngmg−1 and the limit of quantification 17ngmg−1, both were calculated according to the maximum sample mass of 0.50mg. The Si content investigated in ten plant samples varied between 0.5 and 20μgmg−1. The accuracy of the method was evaluated using the certified reference materials NCS ZC73014 (Trace elements in Tea) and NCS ZC73349 (Bush Branches and Leaves) and results presented no significant difference between the certified and found concentrations. Therefore, the obtained results prove that an accurate method has been developed and it could be applied to analyze different plant materials with levels varying in a wide range, with minimum of pretreatment.

Evaluation of Direct Analysis for Trace Elements in Tea and Herbal Beverages by ICP-MS

In general, inductively coupled plasma mass spectrometry (ICP-MS) food analysis requires numerous sample treatment steps that imply an increase of analysis time and the use of chemicals. In this study, the main objective was to evaluate the applicability of the direct analysis by ICP-MS to determine twelve elements (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se and Zn) in tea and herbal beverages. Direct analysis method was compared with two other sample treatments: minimum treatment (acid dilution) and using a destructive method (microwave assisted digestion). Besides the lowest time of analysis, direct analysis provides a reliable response and agrees with the “green chemistry” principles. High sensitivity was also observed by low values of limits of detection and quantification, in general, below 2.5 µg L-1. The method accuracy was evaluated by spiked experiments and values ranged between 82 and 120%. Low values of coefficient of variation were also observed, 2 to 17%, for all analytes. The method exhibited applicability for commercial tea samples as well as for drinks made by herb infusion.

Application of High Resolution-Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS): Determination of trace elements in tea and tisanes

A new application of HR-CS FAAS (High Resolution-Continuum Source Flame Atomic Absorption Spectrometry) has been developed for the determination of several trace elements (Ca, Co, Cu, Fe, Mn, Ni, Na and Zn) in infusions made from tea, rooibos and tea with seaweed samples. The proposed methods are fast, inexpensive and show good performances: the mean analytical recovery was approximately 100%. The mean limit of detection was 29.4μg/l, and the mean limit of quantification was 98.0μg/l (both limits refer to the brewed samples). Due to the matrix effect observed, the standard addition method had to be applied. Preliminary classification (based on metal contents) using chemometric techniques such as PCA (Principal Component Analysis) and CA (Cluster Analysis), was successful for infusions made from rooibos and tea with seaweed, but inconclusive for black and green teas.

Trace Elements in Tea Leaves from Yakushima and their Regional Variations

Trace Elements in Tea Leaves from Yakushima and their Regional Variations

Trace elements in tea leaves commercialized in Brazil

Trace elements in tea leaves commercialized in Brazil

Development of a Certified Reference Material (NMIJ CRM 7505-a) for the Determination of Trace Elements in Tea Leaves

A certified reference material (CRM) for trace elements in tea leaves has been developed in National Metrology Institute of Japan (NMIJ). The CRM was provided as a dry powder (<90 µm) after frozen pulverization of washed and dried fresh tea leaves from a tea plant farm in Shizuoka Prefecture, Japan. Characterization of the property value for each element was carried out exclusively by NMIJ with at least two independent analytical methods, including inductively coupled plasma mass spectrometry (ICP-MS), high-resolution (HR-) ICP-MS, isotope-dilution (ID-) ICP-MS, inductively coupled plasma optical emission spectrometry (ICP-OES), graphite-furnace atomic-absorption spectrometry (GF-AAS) and flame atomic-absorption spectrometry (FAAS). Property values were provided for 19 elements (Ca, K, Mg, P, Al, B, Ba, Cd, Cu, Fe, Li, Mn, Na, Ni, Pb, Rb, Sr, Zn and Co) and informative values for 18 elements (Ti, V, Cr, Y, and all of the lanthanides, except for Pm whose isotopes are exclusively radioactive). The concentration ranges of property values and informative values were from 1.59% (mass) of K to 0.0139 mg kg(-1) of Cd and from 0.6 mg kg(-1) of Ti to 0.0014 mg kg(-1) of Lu, respectively. Combined relatively standard uncertainties of the property values were estimated by considering the uncertainties of the homogeneity, analytical methods, characterization, calibration standard, and dry-mass correction factor. The range of the relative combined standard uncertainties was from 1.5% of Mg and K to 4.1% of Cd.

Application of nuclear techniques to study of trace elements

Trace elements in various materials using nuclear techniques are studied. Results obtained by using energy-dispersive X-ray fluorescence (EDXRF) and proton-induced X-ray emission (PIXE) are examined. The EDXRF method is used to quantitatively evaluate trace elements such as Mn, Fe, Cu, Zn, Br, Rb and Sr in tea leaves. Correlation of trace elements in tea leaves and in the corresponding soil is studied.

Determination of trace elements in tea leaves by neutron activation analysis

Instrumental neutron activation analysis has been employed to determine 14 trace elements in two brands of Iranian and foreign tea. The elements are: Br, La, Ba, K, Mn, Cl, Cr, Cs, Rb, Fe, Co, Zn, Sc and Au. The transference ratio of the elements into solution, when tea is leached by percolation, is also reported. It was found that some elements are totally transferred into solution and some are partially retained by the leaves.

Determination of trace elements in tea and coffee by neutron activation analysis.

Abstract Thermal neutron activation analysis, a high-resolution Ge(Li) gamma-ray spectrometer, and an IBM 360/67 digital computer were used to determine the concentration of Na, K, Sc, Cr, Mn, Fe, Co, Cu, Zn, Se, Br, Rb, Sb, Cs, and Hg in ground coffee and tea. This nondestructive multielement technique requires neither pre- nor postirradiation chemistry and eliminates problems of reagent contamination. The method is simple, precise and sensitive to 15 elements. Interferences from fast neutron (n, p) and (n, α) reactions are small and, if necessary, corrections may be applied easily. This technique can be applied to percolated tea and coffee.