Elemental Composition of Infusions of Herbs (Tisanes) of North Ossetia (the Caucasus)

Abstract

Herbal infusions are consumed worldwide owing to their beneficial properties. Cultivated or obtained from the wild, herbal raw plant materials may contain trace elements at various levels. This study relates to the release of beneficial and potentially toxic trace elements from herbal preparations during infusion. The elemental contents of seven commercially available herbal tea products were determined prior to and following two modes of infusion. Teabags (of equal herb content) were infused in 200 mL of boiling bottled water “Holy Spirit” for 15 and 45 min, in glass beakers. The total content of 57 elements including heavy metals, rare earth elements, as well as Th and U, were determined by ICP-MS and ICP-AES. The metals present in the highest concentrations were K, Ca, P, and S. Potassium, Mg, Co, Ni, As, Rb, and Cs had the highest extractability, whereas Ga, Ge, Se, Zr, Nb, Te, Er, Yb, W, Tl, and U had the lowest extractability.

1. Introduction

Tea (derived from tea bush leaves–Camellia sinensis (L.) Kuntze, known as Camellia chinensis (Sims) Kuntze and Thea chinensis Sims, Theaceae) [1,2,3,4,5] and tea drinks (tisanes, based on herbal harvests) are popular around the world [6,7,8,9,10,11,12,13]. An analysis of a large array of published works including recent data on the components of tea and the tea infusions shows a high interest in the compounds, substances, and individual elements that play an important role in human life [8,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28]. However, for many people, it is important that herbal teas, as a rule, do not contain the caffeine alkaloid (theine) that is characteristic of tea infusions obtained from the leaves of the tea bush [5,29].

The elemental content of the plant materials depends mainly on the plant survival mechanisms, stages of plant growth, and parameters of the environment, e.g., soil characteristics, climatic conditions, agricultural practices, and distance to pollution sources. As such, investigations of raw plant materials are time and location-specific and are necessary to ensure safety and therapeutic effectiveness [30,31,32]. By taking into account the growing popularity and economic importance of medicinal plants, the WHO has developed several traditional medicine strategies [33] that have been aimed at promoting the rational use of both traditional and alternative medicine via evidence-based research.

Studies have demonstrated [1,3,6] that regular consumption of herbal tea can help meet daily dietary requirements of some of the elements necessary for human health, such as Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Se, V, and Zn [3,6,7,12,24]. Regular intake of herbal tea especially contributes to the recommended daily allowance for macro- and micronutrients such as Cr, K, Mn, Ni, and Zn [30,31,32,33,34].

It has been shown that botanical species of medicinal plants cultivated in different climatic conditions, on various types of soil, have a significantly different chemical composition and, subsequently, different content of secondary metabolites, such as flavonoids, alkaloids, terpenoids, quinones, steroids etc. [35,36]. Common preparation methods include decoctions, macerates, herbal teas, and herbal tea mixtures [37,38]. In the case of aqueous solutions (tisanes), the elements present in the plant material depend on numerous factors, such as the specific chemical properties of each element, the form of the plant material (powdered, finely cut, etc.), infusion time, water content and temperature.

This study is a continuation of our research of the elemental composition of herbs cultivated on the territory of the Republic of North Ossetia-Alania (Russia) and sold commercially as herbal tea blends. Neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) were applied to maximize the number of elements determined in the raw plant materials [30]. To investigate the extraction capacity and availability of the elements to the consumer, the same herbal tea mixtures were studied by means of ICP-MS and ICP-AES techniques to determine elemental concentrations both in the dry herbal blends and in the aqueous solutions (tisanes), prepared according to the recommendations by the manufacturer.

The purpose of the work is to estimate the number of elements released into the aqueous solution (tisanes–water infusion of herbs, flowers, and fruits of different plant species), which people consume. A panoramic study of the elemental composition of herbal compositions and their tisanes was performed by complementary analytical methods. Elements present in the tisanes were investigated to differentiate and evaluate their intake. Based on this, recommendations for the use of the studied herbal blends as supplementary sources of balanced nutrition were made. Possible correlations between different elements in the aqueous solutions were investigated.

2. Experimental

2.1. Study Area and Sampling

The raw materials used for the preparation of the tisanes were collected in Russia on the territory of the Republic of North Ossetia-Alania (RNO-A), which is characterized by a distinct microclimatic diversity, a large “mosaic” of ecological conditions, due to the mountainous relief. The region in which the plants were procured is located on the northern macroslopes of the Greater Caucasus. The climate is temperate continental, and the soils are Phaeozems and Umbrosols.

The places for plant materials collection were located in non-urbanized areas at a distance of at least 300 m from major roads, highways, and enterprises, at least 100 m from country roads and individual buildings, and at least 200 m from villages.

For the production of the herbal compositions, at least 100 kg (dry raw materials) of each plant species were collected. The herbal blends consisted of a mixture of vegetative (leaves, stems) and generative organs of plants (flowers, fruits, and seeds) (

Table 1. Terms and locations of the procurement of plant materials in North Ossetia.

Species	Collecting Place	Time of Procurement of Raw Materials, Months	Type of Raw Material
Alchemilla sp. *	4	VI–VIII	Aerial part
Epilobium angustifolium L. (Chamaenerion angustifolium (L.) Schur)	5	VI–VII	Flowers
Crataegus sp. **	2	IX–XI	Fruit
Dasiphora fruticosa (L.) Rydb.	5	VI–VII	Shoots
Ginkgo biloba L.	6	VIII–IX	Leaves
Elaeagnus rhamnoides (L.) A.Nelson (Hippophaë rhamnoides L.)	2	VIII–IX	Fruit
Hypericum perforatum L.	1	VI–VII	Aerial part
Malus domestica Borkh.	6	VIII–IX	Fruit
Melissa officinalis L.	6	VI–VII	Aerial part
Mentha × piperita L.	6	VI–VII	Leaves
Mentha longifolia (L.) L.	1	VI–VII	Leaves
Origanum vulgare L.	1	VI–VII	Aerial part
Pinus sylvestris var. hamata Steven (Pinus kochiana Klotzsch ex K.Koch)	4	VIII–IX	Plant buds
Ribes nigrum L.	6	V–VII	Leaves
Rosa sp. ***	2	VIII–IX	Fruit
Rubus idaeus L. (Rubus buschii (Rozanova) Grossh.)	4	V–VII	Leaves
Rubus idaeus L. (Rubus buschii (Rozanova) Grossh.)	4	V–VII	Shoots
Thymus sp. ****	2	VI–VIII	Aerial part
Tilia cordata Mill.	4	V–VI	Flowers
Trifolium pratense L.	5	V–VII	Inflorescences
Vaccinium arctostaphylos L.	3	VIII–IX	Leaves
Vaccinium arctostaphylos L.	3	VIII–IX	Fruit

Note: 1-southern slopes of the Terskiy and Kabardino-Sunzhenskiy ridges (environs of the village of Zamankul, village of Kardzhin, RSO-A); 2-Chmiyskaya, Naro-Mamissonskaya and Dargavskaya semiarid basins; 3-undergrowth of a beech forest (northern slopes of Mount Tarskaya); 4-mid-mountain forest belt greater than 1000 m above sea level (northern slopes of the Lateral Ridge of the Suargom Gorge); 5-meadows of the forest belt and subalpine meadows, more than 1500 m above sea level. (Dargav gorge, Digor gorge, Suargom pass); 6-cultivated in the foothill regions of the RSO-A *-the generic complex includes the following species: A. sericata Rchb. ex Buser, A. caucasica Buser; **-the generic complex includes the following species: C. monogyna Jacq., C. rhipidophylla Gand.; ***-the generic complex includes the following species: R. corymbifera Borkh., R. canina L., R. oplisthes Boiss. (synonym for R. svanetica Cr‚p. ex Sommier & Levier; ****-the generic complex includes species: Th.pulegioides subsp. pannonicus (All.) Kerguélen (synonym for Th. marschallianus Willd.), Th. daghestanicus Klokov & Des.-Shost., Th. Nummularius M.Bieb. Synonymous plant names are given in parentheses.

), collected and dried according to the approved documentation [39,40]. Aerial parts of plants (flowers, herbs, fruits) were collected in dry weather, after the morning dew dries up (from 8–10 h) and before the appearance of evening dew (up to 17 h). The raw materials were collected only from well-developed plants, healthy and not damaged by insects or microorganisms. The timing of the collection of medicinal plant materials depends on the formation and accumulation of active substances and maximum phytomass. To determine the phenological phases (state of winter dormancy, flowering, fruiting), during which it is necessary to collect the plants, literature data and available regulatory documentation was referenced [39,40]. The herbal mixtures were prepared from the raw materials according to the manufacturer recipes.

Samples with a mass of 100 g were taken from the mixtures for analysis in accordance with a method by the State Pharmacopoeia XIII ed. (Pharmaceutical Article 1.1.0005.15 Sampling of medicinal plant raw materials and medicinal herbal preparations, State Pharmacopoeia of the Russian Federation, Ministry of Health of the Russian Federation. XIII ed. Vol. 1. Moscow, 2015. 1470 p.). Each sample was collected from a box with an herbal mixture by gathering material from three layers: top, second (above the middle of the box), and bottom. The materials from the three layers were then mixed thoroughly to create a combined sample, from which subsamples were collected for analysis.

Materials

The objects of the study were herbal blends (

Table 2. Name and composition of herbal teas [30].

No	Herbal Blends	Composition
1	“Bouquet of Vivacity”	Fruit of Rosa, leaves of Ribes, herbs of Hypericum
2	“Forest Gifts”	Fruit of Rosa, fruit of Crataegus, offshoot of Rubus, leaves of Ribes, leaves and flowers of Chamaenerion, buds of Pinus
3	“The Valley of Health”	Herb of Dasiphora fruticosa, leaves of Ginkgo biloba, flofers of Trifolium
4	“Our Canyon”	Leaves of Mentha, leaves of Ribes, herbs of Origanum, herbs of Thymus, herbs of Hypericum, leaves and flowers of Chamaenerion, leaves of Vaccinium caucasicum, herbs of Achillea
5	“Sea Buckthorn Yummy”	Fruit of Hiepophae, leaves of Rubus, herbs of Melissa, flowers of Tilia, fruit of Malus
6	“Northern Blossom”	leaves and fruit of Vaccinium caucasicum, leaves and flowers of Chamaenerion, green tea (Thea chinensis)
7	“Skifian Strength”	Herb of Dasiphora fruticosa, herbs of Thymus, fruit of Malus

) developed at the research and production center “Bionarium” of the North Ossetian State University named after K.L. Khetagurov (Russia), as well as tisanes prepared using the same samples.

When brewing herbal tea, bottled water (“Saint Spring”) was deliberately used to provide experiment conditions close to those for a typical consumer, as it is known that the extraction capacity of distilled water differs from that of spring water.

2.2. Sample Preparation

Two methods of brewing herbal tea are described below.

Option 1. According to the recipes recommended to the consumers by the manufacturer, they aim to achieve the best organoleptic properties (taste, color, and smell). For the purpose of the study, boiling bottled water “Holy Spirit” was added to the herbal blend and the time for infusion was 10–15 min. The proportions of water and herbs are individual for each composition. The teapot was wrapped during brewing.

Option 2 is a method of preparing the infusion as a dosage form: the herbal blend was mixed thoroughly, water at room temperature was added, the samples were placed in a water bath, insisted for 15 min with periodic stirring, infused at room temperature for 45 min, and stirred.

All data presented were corrected for the content of elements in the bottled water used to prepare the infusions, i.e., the blank was subtracted.

2.3. Analysis (ICP-MS and ICP-AES Techniques)

A graphical representation of the methodological approach is shown in Figure 1.

2.3.1. Mineralization of the Original Herbal Blends

The obtained samples of herbal tea blends were ground in a mill, after which they were dried for 9–10 h at a temperature of 65 °C to constant weight. Then 250 mg of each sample was placed into standard EasyPrep autoclaves of the MARS-5 (CEM, USA) microwave (MW) system with a volume of 100 mL, 7 mL of 65% HNO₃ (65% for analysis, max 0.005 ppm Hg) and 1 drop of 40% HF (40% for analysis) manufactured by Merck (Merck KGaA, Darmstadt, Germany) were added. Before decomposition with a MW furnace, the vessels were left at room temperature for 45 min to remove excess volatile reaction products. The MW digestion procedure consisted of heating to 200 °C for 15 min. The MW radiation power was 800 W at a frequency of 2450 Hz. This temperature was maintained in the system for 25 min, after which the vessels were cooled to 30 °C. The contents of the autoclaves were quantitatively transferred into 50 mL test tubes, at first up to 25 mL with a 2% HNO₃ solution, and then to 50 mL with deionized water distilled in a PTFE Subboiler ECO IR Maassen Subboiler (Maassen GmbH, Reutlingen, Germany) water and acid purification system.

2.3.2. Preparation of Solutions for Measurement by ICP-MS and ICP-AES

The solutions obtained after MW decomposition of the herbal blends were diluted twice with water distilled in a PTFE Subboiler ECO IR Maassen (Maassen GmbH, Reutlingen, Germany) water and acid purification system.

ICP-MS: To carry out the measurements, the initial solutions of herbal tea infusions were diluted five times with a solution of 2% HNO₃ in order to minimize the effect of organic compounds on the detection of elements.

ICP-AES: The herbal infusions were used without dilution. The solutions obtained after MW decomposition of the herbal teas were diluted twice with deionized water similarly to the procedure for ICP-MS.

2.3.3. Measurement of Element Concentration by ICP-MS Method

The elemental content of the studied samples was determined on an X Series II inductively coupled plasma (ICP-MS) quadrupole mass spectrometer (Thermo Scientific, Germany) equipped with a concentric nebulizer and a quartz cyclonic spray chamber cooled by a Peltier element (2 °C). Argon of high purity 99.998% was used as a plasma-forming gas. The plasma power was 1400 W, the plasma-forming argon flow rate was 13 L/min, the auxiliary argon flow rate was 1.25 L/min, the argon spray flow rate was 0.88 L/min, and the plasma sampling depth was 105 rel. units, the rate of solution supply to the plasma is 1 mL/min, the temperature in the spray chamber is 2 °C, the CeO⁺/Ce⁺ level is <2%, the Ba²⁺/Ba⁺ level is <3%.

To control the signal drift and take into account the analysis error during processing of the results, indium was used as an internal standard, which was added to the test solutions at a concentration of 10 μg/L. The calibration dependences of the elements were determined using standard solutions manufactured by High-Purity Standards (High-Purity Standards, North Charleston, SC, USA): Trace Elements in Drinking Water Standard CRM-TMDW (26 elements), 68 Element Standards ICP-MS-68A (Solution A and Solution B) and single-element solutions B, Mg, Al, P, Mn, Co, Ni, Cu, Zn, Sr, Ba. Measurements of elements in the analyzed solutions were carried out using the software of the PlasmaLab spectrometer.

For the quantitative determination of elements, the iPlasmaProQuad program (GEOKHI RAS, Moscow, Russia) was used. Additional processing of the results was carried out in Microsoft Access and Microsoft Excel.

2.3.4. Measurement of Element Concentration by ICP-AES Method

For atomic emission determination, an iCAP-6500 Duo plasma spectrometer (Thermo Scientific) with inductively coupled plasma was used. Spectral measurement range 166–847 nm. The measurements were carried out with an axial view of the plasma. Operating parameters of the plasma: power of the high-frequency generator 1150 W, plasma-forming argon flow 0.55 L/min, transporting argon flow 0.55 L/min, cooling argon flow 12 L/min.

To construct the calibration curve (Al, Ba, Ca, Cd Co, Cr, Cu, K, Mg, Mn, Ni, Sr, Zn), aqueous multielement standard samples from Merck were used. The ICAP-6500 Duo spectrometer system includes dual-view plasma optics; it is possible to record the spectrum both with axial and radial burner positions. The low detection limits of the spectrometer are provided by both the high sensitivity of the detector in the entire spectral range and the very spectral Echelle scheme with cross-dispersion, which has increased luminous intensity and resolution.

2.3.5. Verification of the Developed Analytical Procedure

The Polish certified reference material CTA-OTL-1 (Oriental tobacco leaves) was used to verify the methodological approach and the obtained results using ICP-MS are shown in

Table 3. Quality assurance: measured and certified values for the standard reference material CTA-OTL-1 (Oriental tobacco leaves), results of ICP-MS analysis.

Element	Measured Values, ppm	Certified Values, ppm
	$\overline{\mathbf{x}}$ (n = 6), p = 0.95
Li	22.9 ± 0.3	23.0 ± 1.8
V	3 ± 0.6	3.08 ± 0.42
Cr	2.3 ± 0.2	2.59 ± 0.32
Mn	372 ± 2	412 ± 14
Co	0.84 ± 0.02	0.879 ± 0.039
Ni	5.4 ± 0.2	6.32 ± 0.65
Cu	13 ± 1	14.1 ± 0.5
Zn	43 ± 1	49.9 ± 2.4
As	0.58 ± 0.08	0.539 ± 0.06
Rb	9.2 ± 0.2	9.79 ± 1.27
Sr	211 ± 2	201 ± 20
Mo	0.28 ± 0.01	0.26 *
Cd	1.05 ± 0.02	1.12 ± 0.12
Sb	0.07 ± 0.01	0.075 *
Cs	0.162 ± 0.005	0.177 ± 0.022
Ba	87 ± 1	84.2 ± 11.5
La	1.35 ± 0.62	1.44 ± 0.16
Ce	2.2 ± 1.2	2.69 ± 0.3
Sm	0.19 ± 0.09	0.229 ± 0.052
Eu	0.04 ± 0.01	0.038 ± 0.009
Tb	0.03 ± 0.01	0.032 ± 0.006
Yb	0.06 ± 0.01	0.13 *
Pb	4.4 ± 0.3	4.9 ± 0.8
Th	0.33 ± 0.23	0.348 ± 0.054
U	0.11 ± 0.03	0.1 *

Note: *-information value.

. A comparison was possible with for the certified data for 25 elements, including information values. For the majority of the elements (more than half) the relative difference between the obtained results and the certificate data was less than 5%. A good agreement between the results and the certified CRM values was observed.

3. Results and Discussion

Seven herbal blends (composed of different plants) and their infusions (tisanes) were studied. It was important to investigate the regularity (extraction) of elements in the ready-made drinks (aqueous infusions prepared using bottled water).

Table 4. Results of ICP-AES (Al-Si) and ICP-MS analyses of herbal blends by the Bionarium Scientific and Production Center, Vladikavkaz (content of Al, Ca, Fe, K, Mg, P, S and Si in mg/g and for the rest of the elements–in μg/g).

Element	DL, mg/kg	Tea No. 1	Tea No. 2	Tea No. 3	Tea No. 4	Tea No. 5	Tea No. 6	Tea No. 7
Al	0.002	0.043	0.05	0.17	0.28	0.17	0.33	0.24
Ca	0.002	7.63	6.84	11.1	13.1	2.17	5.51	9.09
Fe	0.002	0.03	0.04	0.13	0.17	0.10	0.13	0.17
K	0.002	9.15	9.63	11.6	15.5	10.1	9.54	11.03
Mg	0.002	1.82	1.64	2.06	2.67	0.99	2.33	1.69
P	0.002	1.39	1.23	1.34	1.79	1.76	1.46	1.52
S	0.006	0.89	0.82	1.46	2.10	1.64	1.58	1.37
Si	0.001	0.21	0.18	0.61	0.97	0.39	0.50	0.80
Ti	0.05	2	3	6	9	5	8	10
V	0.01	0.05	0.06	0.24	0.39	0.23	0.23	0.33
Cr	0.01	0.27	0.36	0.45	1.1	0.68	0.64	1.0
Mn	0.01	59	64	49	71	23	344	130
Co	0.01	0.08	0.10	0.13	0.16	0.05	0.12	0.14
Ni	0.02	1.1	1.2	0.91	1.7	1.3	2.0	0.71
Cu	0.01	4.4	5.0	5.7	7.4	4.7	9.5	5.8
Zn	0.05	13	17	20	33	22	39	20
Ga	0.001	0.01	0.01	0.04	0.06	0.03	0.04	0.05
As	0.01	0.02	0.03	0.07	0.11	0.04	0.15	0.08
Se	0.1	<DL	<DL	<DL	0.17	0.31	<DL	<DL
Rb	0.005	6.4	7.9	5.2	8.0	9.3	21	2.8
Sr	0.01	39	33	44	50	11	16	31
Y	0.001	0.02	0.05	0.05	0.10	0.04	0.08	0.07
Zr	0.05	<DL	<DL	0.2	0.3	0.2	0.2	0.3
Nb	0.002	<DL	<DL	0.02	0.03	0.02	0.02	0.03
Mo	0.05	0.3	0.2	0.3	0.6	1.0	0.2	0.7
Cd	0.002	0.02	0.04	0.01	0.08	0.05	0.33	0.02
Sb	0.002	0.00	0.01	0.01	0.01	0.02	0.04	0.01
Cs	0.001	0.03	0.06	0.02	0.04	0.04	0.13	0.02
Ba	0.010	9.3	9.8	33	37	7.1	24	35
La	0.001	0.04	0.10	0.07	0.22	0.06	0.11	0.10
Ce	0.001	0.06	0.09	0.14	0.40	0.12	0.20	0.21
Pr	0.001	0.01	0.02	0.02	0.05	0.01	0.02	0.02
Nd	0.001	0.02	0.07	0.06	0.17	0.05	0.09	0.09
Sm	0.001	<DL	0.01	0.01	0.03	0.01	0.02	0.02
Eu	0.001	<DL	<DL	0.01	0.01	<DL	0.01	0.01
Gd	0.001	<DL	0.01	0.01	0.03	0.01	0.02	0.02
Dy	0.001	<DL	0.01	0.01	0.02	0.01	0.01	0.01
Er	0.001	<DL	<DL	<DL	0.01	<DL	0.01	0.01
Yb	0.001	<DL	<DL	<DL	0.01	<DL	0.01	0.01
W	0.01	0.04	0.02	0.02	0.03	0.18	0.07	0.04
Tl	0.001	<DL	<DL	<DL	0.01	0.01	0.01	<DL
Pb	0.01	0.10	0.17	0.46	0.43	1.2	1.8	0.69
U	0.001	<DL	<DL	0.01	0.01	<DL	<DL	0.01

Note: DL–detection limit. Uncertainty of determination (%) for the determined elements grouped by intervals: 5–10% (Ba, Ca, K, Mg, Mn, P, S, Si, Sr, Zn, Cd, Co, Cs, Cu, Ni, Rb, Y, As, Ce, La, Nd, Pb, Sb, U, Cr, Gd, Pr, Tl, Dy, Eu, V, Yb); 10–20% (Er, Zr, Sm) and >20% (Al, Ti, Fe, W, Se).

shows the results of the ICP-AES and ICP-MS analyses of elements in the herbal blend samples. The concentration of elements among the seven herbal blends, with rare exceptions, decreased in the following order: K > Ca > P > S > Si-more than 100 μg/g, Mn > Al > Sr > Fe > Zn > Ba-more or about 10 μg/g, Rb > Cu > Ti > Mg > Ni-more or about 1 μg/g, Ni > Mo > Cr > Pb > Co > Ce > V > La > W > Cs > Li > As > Y > Cd > Nd > Ga > Pr-more or about 0.01 μg/g, Sb > Be > Ge > Se > Zr > Nb > Te > Sm > Eu > Gd > Tb > Dy > Ho > Er > Tm > Yb > Lu > Hf > Ta > Re > Tl > Bi > Th > U-less than 0.01 μg/g. Uncertainties of elements determination for majority of elements lies in the range 5–15%.

The highest content of K (15,534 μg/g) was determined in herbal blend No. 4.

Table 5. Elemental content in a 250 mL infusion (Al, Ca, Fe, K, Mg, P, S, Si–in mg, the rest–in μg).

Elem	DL	Tea No. 1		Tea No. 2		Tea No. 3		Tea No. 4		Tea No. 5		Tea No. 6		Tea No. 7
		15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min
Al	0.002	0.03	0.03	0.06	0.03	<DL	0.003	0.004	0.008	0.02	0.05	0.12	0.13	<DL	<DL
Ca	0.0025	10.52	11.77	11.74	12.64	3.31	5.06	9.27	10.27	8.78	10.79	3.68	4.12	3.69	4.4
Fe	0.0025	0.07	0.04	0.05	0.05	0.01	0.02	0.006	0.01	0.09	0.06	0.03	0.03	0.01	0.01
K	0.0025	70.54	69.39	74.14	75.41	30.74	32.76	38.86	40.86	70.71	72.84	25.26	20.61	29.61	28.31
Mg	0.0025	7.54	9.23	8.54	8.71	2.29	2.92	4.03	4.28	4.49	5.04	3.29	3.57	1.96	2.22
P	0.0025	5.97	6.19	5.59	5.22	1.71	1.87	0.44	2.55	4.78	5.27	1.7	1.47	2.16	2.14
S	0.0075	3.77	3.51	3.09	2.26	1.48	2.28	<DL	3.43	3.8	4.29	1.67	1.66	1.49	1.4
Si	0.00125	1.1	0.25	0.89	<DL	<DL	1.2	0.14	0.21	<DL	0.01	0.45	0.33	0.56	<DL
Ti	0.125	4.02	0.58	1.61	0.97	0.14	0.13	0.33	1.04	2.56	0.32	0.03	0.09	<DL	<DL
V	0.025	0.28	0.008	0.25	0.11	0.11	0.12	0.17	0.12	0.29	0.09	0.19	0.11	0.13	0.07
Cr	0.0125	0.91	0.99	1.07	1.59	0.19	0.42	0.21	0.36	1.41	1.27	0.31	0.33	0.25	0.27
Mn	0.05	268.19	304.83	277.16	317.83	47.19	54.86	58.91	71.22	128.54	157.7	382.45	380.94	114.27	147.17
Co	0.0125	0.44	0.4	0.53	0.68	0.19	0.26	0.23	0.26	0.2	0.24	0.13	0.15	0.18	0.22
Ni	0.05	5.19	5.03	5.99	7.76	1	1.76	2.24	2.8	4.06	4.88	3.08	3.08	4.14	0.65
Cu	0.125	16.87	17.19	16.13	14.37	5.07	7.97	4.33	10.48	6.05	14.10	7.27	5.24	5.88	8.17
Zn	0.5	35.27	32.01	50.25	64.61	22.35	27.87	21.81	30.22	85.83	97.29	26.25	28.33	22.73	25.21
As	0.025	0.16	0.12	0.200	0.24	0.09	0.12	0.12	0.14	0.33	0.29	0.31	0.27	0.08	0.12
Rb	0.0125	46.44	54.08	59.56	68.29	12.69	13.46	21.11	20.04	59.45	63.19	52.13	52.83	6.24	6.55
Sr	0.05	72.6	87.06	82.67	94.50	6.24	13.73	27.72	30.92	51.36	56.16	7.84	9.83	5.81	3.64
Y	0.0025	0.13	0.1	0.17	0.2	0.02	0.04	0.02	0.05	0.07	0.08	0.04	0.05	0.03	0.04
Zr	0.0025	0.37	0.64	0.31	0.21	0.03	0.25	0.04	0.13	0.21	0.11	0.06	0.22	0.01	0.04
Mo	0.05	0.38	0.39	0.17	0.06	<DL	0.11	0.25	0.26	1.77	1.33	<DL	<DL	0.12	<DL
Cd	0.005	0.06	0.05	0.08	0.13	0.003	0.02	0.02	0.04	0.20	0.24	0.14	0.17	0.01	0.01
Sb	0.00125	0.006	0.002	0.005	0.02	<DL	0.009	<DL	0.01	0.03	0.02	0.01	0.02	0.02	0.003
Cs	0.00125	0.237	0.28	0.39	0.46	0.03	0.04	0.07	0.06	0.21	0.22	0.28	0.31	0.02	0.02
Ba	0.025	16.62	24.82	18.59	27.56	8.96	19.76	16.47	29.51	31.82	39.44	8.57	12.78	8.77	16.23
La	0.0025	0.103	0.09	0.12	0.16	0.007	0.03	0.009	<DL	0.06	0.05	0.02	0.04	0.006	0.03
Ce	0.005	0.22	0.15	0.16	0.07	0.01	0.05	0.02	0.08	0.12	0.09	0.03	0.06	0.02	0.06
Pr	0.00125	0.02	0.02	0.03	0.04	0.002	0.008	0.003	0.01	0.01	0.01	0.005	0.009	0.003	0.007
Nd	0.0005	0.12	0.09	0.14	0.16	0.02	0.03	0.02	0.04	0.05	0.06	0.03	0.03	0.02	0.03
Sm	0.00125	0.02	0.02	0.03	0.04	0.003	0.01	0.003	0.009	0.01	0.01	0.006	0.008	0.003	0.008
Eu	0.00125	0.008	0.009	0.01	0.01	0.002	0.005	0.004	0.007	0.008	0.009	0.003	0.004	0.002	0.005
Gd	0.00025	0.03	0.02	0.04	0.04	0.005	0.01	0.005	0.01	0.02	0.02	0.008	0.009	0.005	0.009
Yb	0.0005	0.01	0.008	0.01	0.01	0.003	0.005	0.002	0.004	0.008	0.008	0.004	0.005	0.003	0.003
Hf	0.00125	0.013	0.033	0.009	0.01	<DL	0.009	<DL	0.002	0.007	0.004	<DL	0.003	<DL	<DL
W	0.005	0.013	<DL	0.020	0.013	<DL	0.032	<DL	0.01	0.76	0.68	0.01	0.01	<DL	<DL
Tl	0.00125	0.007	0.009	0.008	0.009	0.003	0.004	0.008	0.008	0.03	0.03	0.03	0.03	0.003	0.004
Pb	0.0025	1.95	0.58	1.03	0.82	0.42	0.52	0.77	0.74	3.32	1.98	1.36	0.88	0.51	0.22
U	0.00025	<DL	<DL	0.04	<DL	<DL	<DL	<DL	<DL	<DL	<DL	<DL	0.03	<DL	<DL

Note: DL–detection limit. Measurement uncertainties (%) for the determined elements, grouped by intervals: 5–10% (Ca, K, P, S, Si, Ba, Cu, Mg, Mn, Zn, Ce, Cs, Gd, Nd, Pb, Sm, Cd, Co, Cr, Dy, Eu, La, Ni, Pr, Rb, Sr, U, Tl, Y, Yb, V); 10–20% (As, Mo, Ga, Sb, Ti, W, Zr); >20% (Al, Fe).

summarizes two datasets: the determined concentrations of elements in the infusions of each herbal mixture prepared using different brewing times (Options 1 and 2, Section 2.3). It was observed that the elemental concentrations in most tisanes decreased in the following order: K > Ca > P > S > Si > Mn > Al > Sr > Fe > Zn > Ba > Rb > Cu > Ti > Mg > Ni > Mo > Cr > Co > Ce > V > La > W > Cs > As > Y > Cd > Nd > Ga > Pr > Sb > Be > Ge > Se > Zr > Nb > Te > Sm > Eu > Gd > Tb > Dy > Ho > Er > Tm > Yb > Lu > Hf > Ta > Re > Tl > Bi > Th > U.

The relatively high Na concentration in the bottled water used for tisane preparation (12 mg/L were determined in the blank samples) did not allow the determination of this element in the aqueous solutions, where the concentrations were approximately at the same level. For consistency purposes, Na content measured in the herbal blends is not reported either.

The data shown in Table 5 were subjected to statistical analyses using SPSS (v. 19, IBM Corp., Armonk, NY, USA). Two non-parametric tests, applicable for small sample sizes and non-normal distributions, were chosen.

By design of the experiment, the tisane samples were to be analyzed in a form that a consumer may prepare. The plant material (herbal blends) was therefore not homogenized before brewing. As such, the data were treated as independent.

To verify whether the concentrations of elements in the aqueous solutions prepared using the seven herbal mixtures are distinct, the data were grouped blend-wise, and a Kruskal–Wallis test was performed. Each group consisted of two tisanes (different brewing times) prepared using the same herbal blend (but still non-homogenized samples). Such grouping of the data diminished any effects of the brewing time for each herbal blend individually, but it accounted for the lack of homogenization. It was ascertained that the concentrations of Ba, Ce, Cu, S, Sb, Si, Tb, V, W, and Zr were not statistically different (p > 0.05) between the sets of tisanes prepared using herbal blends No. 1 to 7, no matter the brewing time. However, the concentrations of the majority of the elements (Al, As, Ca, Cd, Co, Cr, Cs, Dy, Er, Eu, Fe, Gd, Hf, Ho, K, La, Mg, Mn, Mo, Nd, Ni, P, Pb, Pr, Rb, Sm, Sr, Th, Ti, Tl, Y, Yb, and Zn) determined in the infusions of each herbal blend were found to be significantly different (p < 0.05).

To test whether brewing time had a strong effect on the elemental composition of the tisanes as a whole, i.e., across all seven herbal blends, the data was organized into two groups: 15-min and 45-min brewing time. A Mann–Whitney U-test demonstrated that the concentrations of most elements in the tisanes were not statistically different (p > 0.05), except for V, which had a significantly greater concentration (p = 0.004) in the case of 15-min brewing time.

The degree of extraction of an element depends on numerous factors: solubility, affinity to the organic herbal matrix, method and time for infusion, initial concentration in the water used for the preparation of tisanes, temperature, ionic strength of the solution [8,41]. Most of the elements are found in flavonoids, tannins, catechols and other biologically active compounds [8,42].

The percentage of extraction in an infusion of 250 mL was calculated for all determined elements (

Table 6. Extraction of elements depending on the brewing time (%).

Element	Tea No. 1		Tea No. 2		Tea No. 3		Tea No. 4		Tea No. 5		Tea No. 6		Tea No. 7
	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min	15 min	45 min
Al	8	7	15	9	0	1	1	1	2	4	15	15	0	0
Ca	17	19	21	23	12	18	28	31	51	62	27	30	16	19
Fe	26	15	17	16	3	4	1	2	11	7	10	7	2	2
K	96	95	96	98	100	100	100	100	88	91	100	86	100	100
Mg	52	63	65	66	44	57	60	64	57	64	56	61	46	53
P	54	56	57	53	51	56	10	57	34	37	46	40	57	56
S	53	49	47	35	41	63	0	65	29	33	42	42	43	41
Si	65	15	60	0	0	78	6	9	0	0	36	32	28	0
Ti	26	4	7	4	1	1	1	5	6	1	0	0	0	0
V	76	2	54	23	18	20	18	12	16	5	32	18	15	9
Cr	43	47	37	55	17	37	8	13	26	23	20	20	10	11
Mn	57	65	54	62	38	45	33	40	70	86	44	44	35	45
Co	69	62	65	82	59	76	57	62	45	51	45	48	53	59
Ni	62	60	64	83	44	78	54	68	38	46	61	61
Cu	48	49	40	36	36	56	23	57	16	37	30	22	41	57
Zn	34	31	38	49	46	57	26	37	49	56	27	29	45	50
Ga	0	3	15	20	0	0	0	0	4	0	7	0	0	0
As	92	57	94	100	49	52	45	43	93	77	80	63	41	47
Rb	91	100	94	100	97	100	100	100	80	85	98	100	91	95
Sr	23	28	31	35	6	12	22	25	60	65	20	25	8	5
Y	78	58	43	50	19	36	7	19	21	23	21	25	15	24
Zr	0	0	0	0	4	40	6	17	13	7	11	38	2	5
Mo	15	13	9	1	0	7	16	13	21	15	0	0	7	0
Cd	34	26	23	36	8	27	9	15	48	57	17	20	17	10
Sb	24	9	6	18	0	43	0	53	22	16	13	22	47	9
Cs	88	100	82	96	53	73	66	58	65	68	85	95	33	28
Ba	22	33	24	35	11	24	18	32	56	69	14	21	10	18
La	30	28	15	21	4	16	2	0	13	11	6	13	2	11
Ce	48	32	22	10	4	14	2	8	13	10	7	11	3	11
Pr	43	37	21	27	6	17	3	9	11	12	10	14	5	11
Nd	53	42	26	30	10	22	4	10	14	15	12	15	9	14
Sm	0	0	29	35	11	27	4	10	13	16	12	15	6	14
Eu	0	0	0	0	13	23	14	21	0	0	17	20	10	18
Gd	0	0	34	39	16	30	6	14	19	18	17	21	11	19
Yb	0	0	0	0	0	0	10	18	0	0	21	22	15	15
W	5	0	13	5	0	56	0	6	54	48	7	3	0	0
Tl	0	0	0	0	0	0	54	46	68	69	79	84	0	0
Pb		70	74	59	36	45	71	68	35	21	30	19	30	12

). An evaluation of the extraction into the infusion was carried out separately, according to the used methods for brewing (15-min water bath—Option 1 and 15 min water bath + 45 min at room temperature—Option 2).

According to the degree of extraction, elements can be divided into three groups [43]: effortlessly extractable elements (>55%): K, Mg, Li, Co, Ni, As, Rb, and Cs; moderately extractable elements (20–55%): Mg, P, S, Si, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Cd, Ba, Nd, Gd, Sb, V; poorly extractable elements (<20%): Ga, Ge, Se, Zr, Nb, Te, Er, Yb, W, Tl, Pb, U.

In this work, the following elements have the highest percentage of extraction in all herbal tea samples (Table 6): K (86–100%), Rb (80–100%), Cs (53–100%), As (43–100%). Many researchers argue that K [42,44,45,46], Rb, and Ni [42] have a high level of extractability into the solution. This can be explained by the chemical properties of K, its presence in the form of inorganic species in the plant cell, and its large amount in the extracellular space [12,47]. The high percentage of extraction of these elements indicates their lability in the plant, while those elements for which the extraction rate is relatively low are much more strongly bound to the organic matrix and are hardly extracted during infusion. Differences in the extraction efficiency of the elements reflect their ionic and covalent characteristics and the chemical and biological properties in plants, additionally affect their solubility in herbal infusion [43].

With increasing infusion time, the percentage of extraction increased for the following elements: Ca, Mg, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Cs, Ba, La, Nd, and Gd (Table 6). Mg, which is a component of chlorophyll in plant plastids, is easily transformed into the infusion (44–66% in our study) and it has been reported previously that it is easier to extract than Ca (12–62%) [47,48].

The extraction of the elements Al, Fe, K, P, S, Si, Ti, V, Cu, Rb, Sr, Mo, Ce, Pr, and Pb did not appear to be affected by the infusion time. According to the literature, the highest solubility of such elements as Al, Ba, Ca, Cr, Cu, Fe, K, Mn, Ni, P, Rb, S, Sr, Ti and Zn occurs during the first 5 min of infusion [8]. Additionally, the literature states that at water temperatures above 60 °C, there will be a decrease in the rate of extraction of elements such as Cu and Fe into the solution [41]. In our study, the percentage of extraction of the same elements varies in different herbal tea samples (for Ca in tea No. 1 it was 17–19%, whereas in tea No. 5 it was 51–62%). This can be explained by the different compositions of the herbal blends and the mutual influence of the used plants on each other. The results in Table 5 showed that the highest concentration in the infusions was achieved for K (75.412 mg–tea No. 2), Ca (12.640 mg–tea No. 2), Mg (9.225 mg–tea No. 1), P (6.193 mg–tea No. 1), S (4.286 mg–tea No. 5), Si (0.555 mg–tea No. 7), Al (0.127 mg–tea No. 6).

A high level of extraction (Table 6) of such elements as arsenic (41–100%), lead (74–59% in herbal tea No. 2), copper (41–57% in herbal tea No. 7), zinc (46–57% in herbal tea No. 3), cadmium (48–57%) is worrisome. However, these elements were present at low concentrations in the tea infusion (Table 5) and it could be hypothesized that they may not pose a threat to human health. It should be noted that regulation of such sources of dietary supplementation is not as strict as in the case of drugs, water, and food. Permissible limits for the content of heavy metals in medicinal plants and tisanes have been established for few elements. To check for possible risks associated with consuming the studied herbal teas, the determined concentrations were compared with values set by the World Health Organization as guideline permissible limits for Pb, As, and Cd. Additionally, recommended values for Cu and Zn by the National Institute of Health (Rockville Pike, MD, USA) were included (

Table 7. Results of ICP-AES and ICP-MS analyses of heavy metals in tea infusion (μg/L) in comparison with maximum permissible concentrations.

Element	Pb	Cu	Zn	As	Cd
Detection limit, μg/L	0.01	0.5	2	0.1	0.02
Used water	0.59	2.6	28	<DL	<DL
Tea No 1	2.9	71	156	0.5	0.2
Tea No 2	3.9	60	286	1	0.52
Tea No 3	2.7	34	139	0.5	0.06
Tea No 4	3.5	44	149	0.6	0.14
Tea No 5	8.5	59	417	1.2	0.97
Tea No 6	4.1	24	141	1.1	0.69
Tea No 7	1.5	35	129	0.5	0.04
Russia *	300	3000	10000	100	30
WHO **, mg/kg	10	-	-	10	0.3
DRI ***, mg/d **	-	700–900	8.0–11	-	-

Note: DL–detection limit. * Maximum permissible concentrations of heavy metals and arsenic in food–raw materials and food products (approved by the Chief State Sanitary Doctor of the USSR on 31 March 1986, N 4089-86) Drinks with infusions and essences; ** WHO (World Health Organization). WHO Guidelines for Assessing Quality of Herbal Medicines with Reference to Contaminants and Residues; World Health Organ: Geneva, Switzerland, 2007. *** Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes, Elements Food and Nutrition Board, National Academies (https://www.ncbi.nlm.nih.gov/books/NBK545442/table/appJ_tab3/?report=objectonly accessed date: 31 August 2021).

). A comparison was also made with the maximum permissible concentrations of heavy metals and arsenic in food (raw materials and food products) set in the USSR (Pb, Cu, Zn, As, and Cd). It can be concluded that all seven herbal teas have concentrations of the abovementioned elements below the guideline permissible limits.

3.1. Biological Significance

Each herbal tea is characterized by its elemental composition. Depending on the elemental composition, each herbal tea can be a source of various elements necessary for the human body.

With the aim to emphasize possible health benefits related to the consumption of the tisanes,

Table 8. Characteristics of essential elements.

Element	Tisanes No.	Concentration, mg/g (in Dry Mix)	Content in 250 mL (Option 1)		Content in 250 mL (Option 2)		Recovery in the Infusion (Option 1)		References
				% of Daily Needs		% of Daily Needs		Recovery in the Infusion (Option 2)
K mg	1 2 3 4 5 6 7	9.15 9.63 11.60 15.50 10.10 9.54 11.03	70.54 74.14 30.74 38.86 70.71 25.26 29.61	2.7 2.8 1.0 1.5 2.7 0.9 1.0	69.39 75.41 32.76 40.86 72.84 20.61 28.31	2.6 2.9 1.0 1.5 2.8 0.8 1.1	96 96 100 100 88 100 100	95 98 100 100 91 86 100	>55% [42,43] 73% [44] min 82.82– max 93.09% [45] 28% [46]
Mg mg	1 2 3 4 5 6 7	1.82 1.64 2.06 2.67 0.99 2.33 1.69	7.54 8.54 2.29 4.03 4.49 3.29 1.96	2.3 2.6 0.7 1.3 1.4 1.0 0.6	9.23 8.71 2.92 4.28 5.04 3.57 2.22	2.8 2.7 0.9 1.3 1.5 1.0 0.6	52 65 44 60 57 56 46	63 66 57 64 64 61 53	48.11 min–88.41 max% [45] 38% [44] 20–55% [43]
Ca mg	1 2 3 4 5 6 7	7.63 6.84 11.10 13.10 2.17 5.51 9.09	10.52 11.74 3.31 9.27 8.78 3.68 3.69	1.1 1.2 0.3 0.9 0.9 0.4 0.4	11.77 12.64 5.06 10.27 10.79 4.12 4.40	1.2 1.3 0.5 1.0 1.1 0.4 0.4	17 21 12 28 51 27 16	19 23 18 31 62 30 19	19 min–54.8 max% [45] 18%–[44]
P mg	1 2 3 4 5 6 7	1.39 1.23 1.34 1.79 1.76 1.46 1.52	5.97 5.59 1.71 0.44 4.78 1.70 2.16	0.9 0.8 0.2 0.1 0.7 0.2 0.3	6.19 5.22 1.87 2.55 5.27 1.47 2.14	0.9 0.7 0.3 0.4 0.8 0.2 0.3	54 57 51 10 34 46 57	56 53 56 57 37 40 56	43%–[44] 20–55%–[43]
Fe mg	1 2 3 4 5 6 7	0.03 0.04 0.13 0.17 0.10 0.13 0.17	0.07 0.05 0.01 0.01 0.09 0.03 0.01	0.8 0.7 0.1 0.1 1.1 0.4 0.1	0.04 0.05 0.02 0.01 0.06 0.03 0.01	0.5 0.7 0.2 0.1 0.8 0.3 0.2	26 17 3 1 11 10 2	15 16 4 2 7 7 2	1.12 min–7.95 max% [45] 10%–[44]
Cr mg	1 2 3 4 5 6 7	0.27 0.36 0.45 1.10 0.68 0.64 1.00	0.91 1.07 0.19 0.21 1.41 0.31 0.25	3.6 4.2 0.8 0.8 5.6 1.2 1.0	0.99 1.59 0.42 0.36 1.27 0.33 0.27	3.9 6.3 1.7 1.4 5.0 1.3 1.0	43 37 17 8 26 20 10	47 55 37 13 23 20 11	20–55% [42]
Cu mg	1 2 3 4 5 6 7	4.4 5.0 5.7 7.4 4.7 9.5 5.8	16.87 16.13 5.07 4.33 6.05 7.27 5.88	1.8 1.7 0.5 0.47 0.67 0.80 0.64	17.19 14.37 7.97 10.48 14.10 5.24 8.17	1.9 1.6 0.9 1.2 1.6 0.6 0.9	48 40 36 23 16 30 41	49 36 56 57 37 22 57	11.04 min–70.11 max% [45] 33% [44] 20–55% [42]
Mn μg	1 2 3 4 5 6 7	59 64 49 71 23 344 130	268.19 277.16 47.19 58.91 128.54 382.45 114.27	14.9 15.39 2.62 3.27 7.14 21.24 6.34	304.83 317.83 54.86 71.22 157.70 380.94 147.17	16.0 17.6 3.0 3.9 8.7 21.1 8.2	57 54 38 33 70 44 35	65 62 45 40 86 44 45	min 29.48–max 60.15% [45] 24% [44] 20–55% [43] 20–55% [42]
Mo μg	1 2 3 4 5 6 7	0.3 0.2 0.3 0.6 1.0 0.2 0.7	0.38 0.17 0.000 0.25 1.77 0.00 0.12	0.84 0.386 0.00 0.564 3.93 0.00 0.27	0.39 0.06 0.11 0.26 1.33 0.00 0.00	0.9 0.1 0.2 0.6 2.9 0.0 0.0	15 9 0 16 21 0 7	13 1 7 13 15 0 0	<20% [43]
Zn μg	1 2 3 4 5 6 7	13 17 20 33 22 39 20	35.27 50.25 22.35 21.81 85.83 26.25 22.73	0.44 0.63 0.27 0.27 1.07 0.30 0.28	32.01 64.61 27.87 30.22 97.29 28.33 25.21	0.4 0.8 0.4 0.4 1.2 0.4 0.3	34 38 46 26 49 27 45	31 49 57 37 56 29 50	36% [44] 4.6–73.7% [45] 20–55% [43]
Se μg	1 2 3 4 5 6 7	<DL <DL <DL 0.17 0.31 <DL <DL	0.00 0.00 0.00 0.00 0.00 0.00 0.00	0.000 0.000 0.000 0.000 0.000 0.000 0.000	0.00 0.00 0.00 0.00 0.59 0.00 0.00	0.0 0.0 0.0 0.0 1.1 0.0 0.0	0 0 0 0 0 0 0	0 0 0 0 23 0 0

Note: DL–detection limit.

highlights general characteristics of the essential macro and microelements K, Mg, Ca, P, Fe, Cr, Cu, Mn, Mo, Zn, and Se determined in the studied herbal blends and tisanes. To assess to what degree they could be considered as valuable sources of supplementation with the aforementioned nutrients recommended dietary allowances and adequate intakes were referred.

If we pay attention to the percentage of the listed elements (except for Se) in infusions from the daily norm, it becomes obvious that for consumers the difference between infusions prepared in the two different ways is not particularly significant. This was also demonstrated with the Mann–Whitney U-test performed on the concentration data in Table 5.

To provide 10% of the recommended daily intake of K for women (2600 mg/d), 4 cups of tea No. 5 (250 mL) should be consumed and 3.5 cups of tea No. 2, for men (3400 mg/d)-4, 5 cups of tea No. 2.

10% of the daily value of Mg (320 mg/d) can be supplied by 4 cups of tea No. 1 and No. 2. To provide 10% of the daily intake of Ca (1000 mg/d), 10 cups of tea No. 1 or No. 4 are necessary, and 9 cups of tea No. 2. To provide 10% of the daily intake of phosphorus (700 mg/d), 12 cups of tea No. 1 or No. 2 are needed.

To meet the 10% the recommended daily requirement of molybdenum (45 μg/d), 2.5 cups of tea No. 5 are required. For 10% of the iron for men (8 mg/d) 9 cups of tea No. 5 should be enough. For a 10% of the chromium norm of 25 mg/d, women need 2 cups of tea No. 5, or 2.3 cups of tea No. 2, or 3 cups of tea No. 1; for men–3.3 cups of tea No. 2 or 2.5 cups of tea No. 5. For a 10% copper daily value of 900 μg/d, the consumer needs 5 cups of tea No. 1 and 5.5 cups of tea No. 2.

To satisfy the entire daily intake of manganese for women, 1.8 mg/d, 7 cups of tea No. 1, 6.5 cups of tea No. 2 or 5 cups of tea No. 6 should be consumed; for men, 2.3 mg/d, 6 cups of tea No. 6 are needed. Regarding the recommended daily zinc intake for women (8 mg/d), they should consume 9.3 cups of tea No. 5.

K serves as one of the defining parameters of mineral metabolism. It is involved in the regulation of acid-base balance in the body, and also plays a leading role in the emergence and conduction of nerve impulses. An electrolyte imbalance of potassium/sodium leads to serious disorders of the cardiovascular and nervous systems [49].

Mg possesses a high chemical affinity for oxygen; therefore, it normally actively participates in metabolism and is a universal regulator of biochemical and physiological processes. Suboptimal levels of magnesium lead to a decrease in the rate of oxidative reactions and, consequently, to metabolic and thermoregulation disorders. In addition, magnesium is one of the main elements necessary for the functioning of the nervous system [49].

Ca content and its metabolism determine the physiological homeostasis throughout a person’s life. This element is involved in the most important metabolic processes (glycogenolysis, gluconeogenesis, lipolysis, etc.) and supplies the body with energy [11,49]. It is the major component of the bones and teeth conferring their strength and structure. Calcium is the main structural constituent of cell membranes and is also found in genetic materials such as DNA and RNA.

Fe is a vital element for the body. Iron is found not only in hemoglobin but also in the protoplasm of all cells. It is also part of the cytochromes involved in the processes of tissue respiration [50].

Cr is involved in the interaction of insulin with its receptors. With a chromium deficiency, glucose tolerance is impaired and is only restored after the elimination of the micronutrient deficiency [50].

Cu is important for iron metabolism; it oxidases iron to the form that is necessary for red blood cell formation. It is reported to have anti-inflammatory and anti-infectious properties, as it is used to treat inflammatory rheumatic conditions, and it fights off free radicals [11].

Mn is a part of such enzymes as arginase, pyruvate carboxylase, and superoxide dismutase. This element plays an important role in the processes of the central nervous system, and its deficiency directly affects the functions of the brain [21].

Mo has a beneficial effect on the intestinal microflora, and it is also part of a number of enzymes such as xanthine oxidase, aldehyde oxidase, and sulfite oxidase. Xanthine oxidase plays an important role in purine metabolism; its deficiency, including due to the lack of molybdenum, leads to the accumulation of intermediate metabolic products. Sulfite oxidase converts sulfites to sulfates. The accumulation of sulfites during enzymatic deficiency can lead to damage to the nervous system [21].

Zn is part of a large number of enzymes and plays an important role in biochemical processes in the human body. Zinc is essential for the normal development of children in the first stages of their life, taking part in the formation and functioning of the immune system, intestines (regulation of the absorption of water and electrolytes), and antioxidant protection [21].

Se is part of the enzyme glutathione peroxidase, which is involved in antioxidant protection. It takes part in the regulation of the activity of cytochrome P450 and a number of enzymes. Selenium is also considered an anticarcinogenic factor [21].

Since selenium is not easily extracted, its content in the aqueous solution may potentially increase with prolonged brewing time (Option 2).

3.2. Pairwise Correlations between Elements

The correlation analysis revealed relationships between many elements considered essential (see

Table 9. Correlations between essential and beneficial elements.

Element	Ca	Fe	K	Mg	P	S	Si	Mn	Co	Ni	Cu	Zn	Se	Mo
Ca	1
Fe	0.77	1.00
K	0.95	0.89	1.00
Mg	0.90	0.76	0.89	1.00
P	0.92	0.87	0.97	0.92	1.00
S	0.84	0.66	0.81	0.64	0.78	1.00
Si	−0.18	−0.25	−0.17	−0.12	−0.22	0.04	1.00
Mn	0.44	0.59	0.46	0.68	0.52	0.22	−0.15	1.00
Co	0.81	0.65	0.80	0.86	0.75	0.41	−0.09	0.53	1.00
Ni	0.87	0.89	0.89	0.91	0.85	0.59	−0.20	0.67	0.87	1.00
Cu	0.95	0.78	0.96	0.91	0.97	0.84	−0.11	0.46	0.77	0.80	1.00
Zn	0.70	0.90	0.81	0.52	0.72	0.72	−0.23	0.31	0.49	0.72	0.68	1.00
Se	−0.65	−0.48	−0.62	−0.58	−0.57	−0.69	−0.25	−0.52	−0.55	−0.51	−0.70	−0.52	1.00
Mo	0.47	0.65	0.57	0.24	0.56	0.74	−0.21	−0.05	0.00	0.34	0.50	0.79	−0.20	1.00

). Potassium shows high positive interactions with a large number of elements: K–Ca (R = 0.95), K–P (R = 0.97), K–Mg (R = 0.89), K–Fe (R = 0.89), K–Ni (R = 0.89), K–S (R = 0.81), K–Co (R = 0.80), K–Cu (R = 0.96), K–Zn (R = 0.81). The literature also indicates high correlations between the alkaline element K with almost all macronutrients. This can be explained by the importance of potassium as an electrolyte in plant metabolism [51]. There is also evidence of the correlation of the alkaline earth metals calcium and magnesium, both with each other Ca–Mg (R = 0.90) and with other macronutrients, P–Mg (R = 0.92), Ca–P (R = 0.92). A positive correlation is observed between iron and few elements Zn–Fe (R = 0.90), Fe–Ni (R = 0.89).

Table 10. Correlation between rare earth metals.

Element	Y	La	Ce	Pr	Nd	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu
Y	1.00
La	0.96	1.00
Ce	0.45	0.43	1.00
Pr	0.99	0.95	0.47	1.00
Nd	1.00	0.95	0.47	1.00	1.00
Sm	0.99	0.97	0.47	0.99	1.00	1.00
Eu	0.92	0.81	0.67	0.91	0.92	0.90	1.00
Gd	1.00	0.96	0.48	1.00	1.00	1.00	0.91	1.00
Tb	0.97	0.96	0.39	0.98	0.97	0.97	0.84	0.97	1.00
Dy	1.00	0.95	0.46	1.00	1.00	0.99	0.91	1.00	0.96	1.00
Ho	1.00	0.96	0.48	0.99	1.00	0.99	0.92	0.99	0.97	0.99	1.00
Er	1.00	0.96	0.44	0.99	0.99	0.99	0.91	0.99	0.97	1.00	0.99	1.00
Tm	0.55	0.58	−0.36	0.56	0.55	0.55	0.25	0.54	0.68	0.53	0.56	0.55	1.00
Yb	0.98	0.93	0.48	0.96	0.97	0.97	0.94	0.97	0.93	0.98	0.98	0.99	0.46	1.00
Lu	0.75	0.75	−0.19	0.76	0.75	0.74	0.48	0.74	0.82	0.74	0.75	0.75	0.95	0.68	1.00

shows that the determined lanthanides correlate with each other: Dy–Sm (R = 0.99), Gd–Eu (R = 0.91), Er–Ho (R = 0.99), Pr–Nd (R = 1). This relationship can be explained by the trivalent charge state of the cations of these elements and the very close radius of hydrated ions [51].

4. Conclusions

The herbal tea blends used for the preparation of the studied tisanes showed a good balance of macro and microelements. The obtained data showed that the concentrations of elements in 7 samples of herbal tea blends, with rare exceptions, followed the order: K > Ca > P > S > Si > Mn > Al > Sr > Fe > Zn > Ba > Rb > Cu > Ti > Mg > Ni > Mo > Cr > Co > Ce > V > La > W > Cs > As > Y > Cd > Nd > Ga > Pr > Sb > Be > Ge > Se > Zr > Nb > Te > Sm > Eu > Gd > Tb > Dy > Ho > Er > Tm > Yb > Lu > Hf > Ta > Re > Tl > Bi > Th > U.

Given that the extraction capacity of distilled water differs from that of bottled water, it was decided to perform the experiments in conditions most closely resembling those typical for a tisane consumer. Two approaches of brewing the herbal blends with bottled water were tested and it was ascertained that the extraction of K, Fe, Mo was generally not affected by the time of infusion, whereas the extraction of Cu, Cr, Ca, Mg, Zn, Mn, P, Se in all or most of the tisanes increased over time. A correlation was found between the content of essential elements and between the lanthanides in herbal teas with varied compositions.

This study of aqueous extracts from herbal teas, consisting of a number of medicinal plants, showed that:

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the combination of different raw plant materials into a single herbal blend used for brewing herbal tea provided a large set of elements recommended for daily dietary intake.

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regular consumption use of the tisanes provides valuable supplementation with vital macro- and microelements.

By applying a Kruskal–Wallis test on the data obtained for tisanes, it was demonstrated that not only are the organoleptic properties of the herbal blends different but, when consumed as tisanes, based on their elemental content, they are also distinct sources of soluble substances. To verify that the tisanes did not contain Pb, Cd, Cu, and As at potentially harmful concentrations, maximum permissible levels by the World Health Organization and the National Institute of Health Further were consulted.

The present experimental design does not provide the possibility to differentiate between the content of the used plant materials and their mixtures in the blends. Further research efforts will allow revealing any significant statistical relationships, both univariate and multivariate, between the elements present in the plant materials for the herbal blends and the tisanes.