Polarized X ray fluorescence spectrometer (EDPXRF) for the determination of essential and non essential elements in tea

The Potential Use of Near Infrared Spectroscopy (NIRS) to Determine the Heavy Metals and the Percentage of Blends in Tea

The following study analyzed the potential of Near Infrared Spectroscopy (NIRS) to predict the metal composition (Al, Pb, As, Hg and Cu) of tea and for establishing discriminant models for pure teas (green, red, and black) and their different blends. A total of 322 samples of pure black, red, and green teas and binary blends were analyzed. The results showed that pure red teas had the highest content of As and Pb, green teas were the only ones containing Hg, and black teas showed higher levels of Cu. NIRS allowed to predict the content of Al, Pb, As, Hg, and Cu with ratio performance deviation values > 3 for all of them. Additionally, it was possible to discriminate pure samples from their respective blends with an accuracy of 98.3% in calibration and 92.3% in validation. However, when the samples were discriminated according to the percentage of blending (>95%, 95-85%, 85-75%, or 75-50% of pure tea) 100% of the samples of 10 out of 12 groups were correctly classified in calibration, but only the groups with a level of pure tea of >95% showed 100% of the samples as being correctly classified as to validation.

Investigation of carbonate addition on risk element concentrations in various teas

Healthy nutrition requires to notice risk element content of daily ingested foods and beverages. Several tea types are frequently consumed beverages in daily routine and social situations. Carbonate, although it is not in the natural ingredients of tea, can be added to maintain more brew. Also it gives brilliant red colour while reducing the brewing cost. For this respect, in this study, carbonate added infusions of some black teas (black, earl grey and green tea), herbal teas (fennel, mint and sage tea) and fruit teas (apple, lemon and rosehip) was investigated by inductively coupled plasma optical emission spectrometer (ICP-OES) for the determination of carbonate addition to the risk element (Al, As, Ba, Cd, Mo, Pb, Sb and Ti) contents of teas. Also, the microwave digestion analysis applied by dissolving tea powders in acid solution was conducted in order to investigate how much risk element transfer to the brew. Prior to microwave digestion process, the total risk element contents of the tea grains were determined by again ICP-OES. Furthermore, health risk assessment studies including non-carcinogenic and carcinogenic risks were conducted. According to the health risk assessment results of 200 mL daily consumed teas, hazard index (HI) was found less than 1 and target carcinogenic risk (TCR) was determined as less than 1 × 10-4 which shows all selected tea samples are in the low risk group.

Rapid quantitative characterization of tea seedlings under lead-containing aerosol particles stress using Vis-NIR spectra

The problem of excessive lead content in tea has become more and more serious with the development of society and industry. This paper investigated the ability of visible and near-infrared (Vis-NIR) spectroscopy to evaluate foliar lead uptake by tea plants through simulating real air pollution. Lead content of tea leaves in different treatment groups during stress time was measured by inductively coupled plasma mass spectrometry (ICP-MS). It was determined that stomata can be a channel for lead particles in the air and most of the lead entering through the stomata accumulates in the leaves. The spectral variation of treated samples was measured, and it was found that a combination of partial least squares-discriminant analysis (PLS-DA) and spectral responses can perfectly classify the tea samples under different lead concentrations stress with an overall accuracy of 0.979. Then the Vis-NIR spectra were used for fast monitoring physiological and biochemical indicators in tea leaves under atmospheric deposition. Relevant spectra pretreatment methods and characteristic wavelength selection approaches were evaluated for quantitative analysis and then optimal prediction models to instantly detect quality indicators in tea samples were built. Among predictive models, PLS had the best results (RMSE = 0.139 mg/g, 0.663 mmol/g, and 1.494 μmol/g) for the prediction of chlorophyll a (Chl-a), ascorbic acid (ASA), and glutathione (GSH), respectively. Also, principal component regression (PCR) gave the best results (RMSE = 0.053 mg/g, 0.024 mg/g, and 0.011%) for prediction of chlorophyll b (Chl-b), carotenoid (Car) and moisture content (MC), respectively. Results of this study can be applied for developing an effective and reliable approach for monitoring atmospheric deposition in plants.

Impact of processing method on selected trace elements content of green tea: Does CTC green tea infusion possess risk towards human health?

This study reported the content of selected metals, viz. cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb) and zinc (Zn) as well as non-carcinogenic risks of orthodox green tea and CTC (crush, tear and curl) green tea (Camellia sinensis L.) in India. Results revealed that significantly higher amount of Cr (1.26-10.48 mg kg-1), Cu (13.40-22.73 mg kg-1), Fe (54.14-99.65 mg kg-1), Ni (3.43-7.09 mg kg-1), and Zn (25.04-38.04 mg kg-1) in CTC green tea than orthodox one. However, no definite trend was observed for Cd and Pb, with overall contents ranged from 6.68 to 23.32 µg kg-1 and 0.04 to 0.13 mg kg-1, respectively. The extraction of the elements in tea infusion was higher for CTC green tea. The hazard quotient and hazard index values of all the studied metals were less than unity, confirming no significant health effect for consumers assuming drinking of 750 mL tea infusion prepared from 10 g green tea per day per person.

Features of sample preparation techniques in the total-reflection X-ray fluorescence analysis of tea leaves

Tea is a popular drink around the world and contains essential minerals and trace elements for human health. In this study, the analytical capabilities of the total-reflection X-ray fluorescence method (TXRF) were considered for the analysis of tea. Different sample preparation techniques, e.g. suspension, open vessel acid digestion, and microwave acid digestion were examined. The influence of particle size was investigated in the analysis of the suspension of tea samples. Mass-absorption coefficients for the tea matrix and the critical surface density of the specimen were calculated. The data obtained explain the presence of absorption effects in the determination of P, S, Cl, and K in suspensions. The digestion procedure is chosen as an optimal sample preparation technique for the TXRF analysis of tea. Nineteen real tea samples were analyzed using TXRF. The advantages of TXRF have been presented through the comparison of results with the wavelength-dispersive X-ray fluorescence spectrometry method.

Green Tea Quality Evaluation Based on Its Catechins and Metals Composition in Combination with Chemometric Analysis

Green tea infusions are one of the most popular beverages consumed across the world, especially is Asian countries. Green tea quality is primarily based on catechin content, however, the concentration of elements could also significantly influence its biological properties and thus quality and safety. The main purpose of the present study was the evaluation of catechin, antioxidant activity and metal content (K, Na, Ca, Mg, Fe, Mn, Cu, Zn, Cr, Pb, Cd and Ni) in different green tea types cultivated in Japan, Sri Lanka, South Korea, India, China and Japan. The chemical analysis of samples was performed using LC-ESI-Q-TOF-MS for organic constituents and atomic absorption spectrometry (flame and electrothermal) method for inorganic ones. The obtained results were subjected to chemometric elaboration. EGC (213 mg/100 mL of the tea infusion in South Korean Jeoncha) and EGCG (124 mg/100 mL in Japanese Sencha) were the dominant catechins in all green tea samples. Chinese and Indian green tea samples contained the highest concentration of toxic heavy metals, however these values were far below appropriate limitations for green teas. PCA revealed significant similarities between Japanese samples and Korean Jeoncha. In general the latter one was evaluated to have the best quality based on the investigated parameters.

Assessment of the Bioaccessibility of Trace Elements in Cat's Claw Teas by In Vitro Simulated Gastrointestinal Digestion Using FAAS

The aim of this study was to evaluate the bioaccessibility of Ca, Fe, Mg, Mn, and Zn in cat's claw plant teas through in vitro gastrointestinal digestion with gastric and intestinal juice solutions. The total concentrations and bioaccessible fractions of Ca, Fe, Mg, Mn, and Zn were measured by flame atomic absorption spectrometry (FAAS). The results obtained showed that Zn was the most bioaccessible element in the teas, contributing a mean of 57.9% by infusion and 62.5% by decoction. Among macroelements, the Ca was less bioaccessible with 17.4% recovery. The bioavailability assessment revealed that daily intake of 200 ml of cat's claw teas cover about 1.0% of manganese RDA.

Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review

Tea (Camellia sinensis L.) is a perennial acidophilic crop, and known to be a nonalcoholic stimulating beverage that is most widely consumed after water. The aim of this review paper is to provide a detailed documentation of selected micronutrient contents, viz. boron (B), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) in made tea and tea infusion. Available data from the literature were used to calculate human health aspect associated with the consumption of tea infusion. A wide range of micronutrients reported in both made tea and tea infusion could be the major sources of micronutrients for human. The content of B, Co, Cu, Fe, Mn, Mo, and Zn in made tea are ranged from 3.04 to 58.44 μg g^-1, below detectable limit (BDL) to 122.4 μg g^-1, BDL to 602 μg g^-1, 0.275 to 13,040 μg g^-1, 0.004 to 15,866 μg g^-1, 0.04 to 570.80 μg g^-1 and 0.01 to 1120 μg g^-1, respectively. Only 3.2 μg L^-1 to 7.25 mg L^-1, 0.01 μg L^-1 to 7 mg L^-1, 3.80 μg L^-1 to 6.13 mg L^-1, 135.59 μg L^-1 -11.05 mg L^-1, 0.05 μg L^-1 to 1980.34 mg L^-1, 0.012 to 3.78 μg L^-1, and 1.12 μg L^-1 to 2.32 μg L^-1 of B, Co, Cu, Fe, Mn, Mo, and Zn, respectively, are found in tea infusion which are lower than the prescribed limit of micronutrients in drinking water by World Health Organization. Furthermore, micronutrient contents in tea infusion depend on infusion procedure as well as on the instrument used for analysis. The proportion of micronutrients found in different tea types are 1.0-88.9% for B, 10-60% for Co, 2.0-97.8% for Cu, 67.8-89.9% for Fe, 71.0-87.4% for Mn, 13.3-34% for Mo, and 34.9-83% for Zn. From the results, it can also be concluded that consumption of three cups of tea infusion per day does not have any adverse effect on human health with respect to the referred micronutrients rather got beneficial effects to human.

Comparative Assessment of Copper, Iron, and Zinc Contents in Selected Indian (Assam) and South African (Thohoyandou) Tea (Camellia sinensis L.) Samples and Their Infusion: A Quest for Health Risks to Consumer

The current study aims to assess the infusion pattern of three important micronutrients namely copper (Cu), iron (Fe), and zinc (Zn) contents from black tea samples produced in Assam (India) and Thohoyandou (South Africa). Average daily intakes and hazardous quotient were reported for these micronutrients. Total content for Cu, Fe, and Zn varied from 2.25 to 48.82 mg kg^-1, 14.75 to 148.18 mg kg^-1, and 28.48 to 106.68 mg kg^-1, respectively. The average contents of each of the three micronutrients were higher in tea leaves samples collected from South Africa than those from India while the contents in tea infusions in Indian samples were higher than in South African tea samples. Results of this study revealed that the consumption of 600 mL tea infusion produced from 24 g of made tea per day may be beneficial to human in terms of these micronutrients content. Application of nonparametric tests revealed that most of the data sets do not satisfy the normality assumptions. Hence, the use of both parametric and nonparametric statistical analysis that subsequently revealed significant differences in elemental contents among Indian and South African tea.

Levels of Trace Elements in Black Teas Commercialized in Saudi Arabia Using Inductively Coupled Plasma Mass Spectrometry

The present work has been demonstrated a developed method for the determination of Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, As, Cr, Pb, and V in different types of black teas collected from Saudi Arabia market using inductively coupled plasma mass spectrometry (ICP-MS). Each sample represents a well-mixed combination of ten packets from the same type collected from the market. Detection limits in ng g^-1 were 76.06, 166.03, 5.94, 2.94, 18.29, 18.29, 9.00, 0.48, 0.48, 7.67, 3.07, and 4.21 for Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, As, Cr, Pb, and V, respectively. In order to validate the developed method, a certified reference material of green tea was analyzed. Further comparison with the results obtained from high-resolution continuum source atomic absorption spectrometry (HR-CS-AAS) was demonstrated. The obtained good agreement confirms the validity of the investigated method. Fortunately, the concentrations of the heavy metals locate on the range of the international values. The highest metal content was found in Al-Rabee tea, and this type results should be confirmed by using a large number of samples in order to have satisfied and confirmed statistical analysis results.

Evaluation of trace metal and polychlorinated biphenyl levels in tea brands of different origin commercialized in Italy

The objectives of this study were to investigate the trace element (Hg, Cd, Pb, Cu, Zn, Ni, Fe, Cr and Se) and polychlorinated biphenyl (PCBs) content of several commercially available brands of green and black tea marketed in Italy. The concentrations these chemicals were found to be variable and largely dependent upon the type and brand of analysed tea. The most abundant element among the essential elements was Fe, followed by Zn, Cu, Se, Ni and Cr, whereas Pb was the predominant among the tested nonessential elements followed by Hg and Cd. Assessment based on several available guidelines showed that element content were low, except for Hg and Ni. The PCBs concentrations were generally low, with a homologue profile dominated by low-chlorinated congeners, namely three- and tetra-PCBs accounting for more than 60% of the total residue. Apart from trace elements, this is the first study documenting in detail the concentrations and congener distribution of PCBs in tea samples of different origin.

Concentrations and solubility of selected trace metals in leaf and bagged black teas commercialized in Poland

The objective of this study was to determine the concentrations of heavy metals in bagged and leaf black teas of the same brand and evaluate the percentage transfer of metals to tea infusion to assess the consumer exposure. Ten leaf black teas and 10 bagged black teas of the same brand available in Poland were analyzed for Zn, Mn, Cd, Pb, Ni, Co, Cr, Al, and Fe concentrations both in dry material and their infusion. The bagged teas contained higher amounts of Pb, Mn, Fe, Ni, Al, and Cr compared with leaf teas of the same brand, whereas the infusions of bagged tea contained higher levels of Mn, Ni, Al, and Cr compared with leaf tea infusions. Generally, the most abundant trace metals in both types of tea were Al and Mn. There was a wide variation in percentage transfer of elements from the dry tea materials to the infusions. The solubility of Ni and Mn was the highest, whereas Fe was insoluble and only a small portion of this metal content may leach into infusion. With respect to the acceptable daily intake of metals, the infusions of both bagged and leaf teas analyzed were found to be safe for human consumption.

Essential and toxic elements in honeys from a region of central Italy

Levels of iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), zinc (Zn), mercury (Hg), cadmium (Cd), and lead (Pb) in several types of honey produced in a region of Central Italy were determined by atomic absorption spectroscopy (AAS). The degree of humidity, sugar content, pH, free acidity, combined acidity (lactones), and total acidity were also measured. These elements were found to be present in honey in various proportions depending upon (1) the area foraged by bees, (2) flower type visited for collection of nectar, and (3) quality of water in the vicinity of the hive. Strong positive correlations occurred between Pb and Hg, Pb and Cd, Pb and Fe, Pb and Cr, Hg and Cd, and Hg and Fe. The honey products synthesized in Central Italy were of good quality, but not completely free of heavy metal contamination. Compared with established recommended daily intakes, heavy metals or trace element intoxication following honey consumption in Italy was found not to be a concern for human health.

Essential and toxic elements in clays for pharmaceutical and cosmetic use

Essential and toxic elements (Al, Si, P, S, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Ba, Cd, Ce, Nd, Pb, U, Th, and La) were determined by energy-dispersive polarized x-ray fluorescence spectrometry (EDPXRF) in 15 samples of clay materials for pharmaceutical and cosmetic use. The investigated samples were grouped according to their mineralogical composition determined by x-ray powder diffraction (XRPD). Samples consisting of smectites showed the lowest content of K, Zn, La, Ce, Nd, Pb, Ti, and Th and highest quantity of Sr, Br, and U. The sample containing smectite and kaolinite displayed the lowest content of Ca, Fe, Mn, Cu, Ni, and Sr and highest amount of Al, Si, Ba, Zn, As, La, Ce, Pb, and Th. Samples composed of illite demonstrated minimal amounts of Br and maximal content of K, Rb, Ti, and Fe. In all samples analyzed, Cd and Hg levels were below 2 mg/kg.

Evaluation of trace metals in tea samples from Jeddah and Jazan, Saudi Arabia by atomic absorption spectrometry

The Cd, Pb, Mn, Zn, Ni, Co, Fe, Cr and Cu content were determined in various teas available in local markets of Jeddah and Jazan, Saudi Arabia. Concentrations of the trace metals were measured after acid digestion using a flame atomic absorption spectrometer. Validation of the digestion procedure was performed by the analysis of a certified reference material. The cadmium, lead, manganese, zinc, nickel, cobalt, iron, chromium and copper concentrations were found in the range of below the detection limit (BDL)--0.7 μg/g, BDL--8.7 μg/g, 48-859 μg/g, 6.6-120 μg/g, BDL--16.9 μg/g, BDL--3.1 μg/g, 46-348 μg/g, BDL--4.9 μg/g and 5.2-21.6 μg/g respectively. The values found in this study were compared with literature values.