Sensitive chemical sensor array based on nanozymes for discrimination of metal ions and teas.

Tea, originating from China, is an important part of Chinese traditional culture. There are different qualities of and producing areas for tea on the market, therefore it is necessary to discriminate between teas in a fast and accurate way. In this study, a chemical sensor array based on nanozymes was developed to discriminate between different metal ions and teas. The indicators for the sensor array are three kinds of nanozymes mimicking laccase (Cu-ATP, Cu-ADP, Cu-AMP). The as-developed sensor array successfully discriminated 12 metal ions and the detection limit was as low as 0.01 µM. The as-developed sensor array was also able to discriminate tea samples. Different kinds of tea samples appeared in different areas in the canonical score plot with different response patterns. Furthermore, in a blind experiment, we successfully discriminated 12 samples with a 100% accuracy. This sensor array integrates chemistry and food science together, realizing the simultaneous detection of several kinds of teas using a sensitive method. The as-developed sensor array would have an application in the tea market and provide a fast and easy method to discriminate between teas.

Qualitative and quantitative 1 H NMR spectroscopy for determination of divalent metal cation concentration in model salt solutions, food supplements, and pharmaceutical products by using EDTA as chelating agent.

This paper introduces an 1 H NMR method to identify individual divalent metal cations Be2+ , Mg2+ , Ca2+ , Sr2+ , Zn2+ , Cd2+ , Hg2+ , Sn2+ , and Pb2+ in aqueous salt solutions through their unique signal shift and coupling after complexation with the salt of ethylenediaminetetraacetic acid (EDTA). Furthermore, quantitative determination applied for the divalent metal cations Ca2+ , Mg2+ , Hg2+ , Sn2+ , Pb2+ , and Zn2+ (limit of quantification: 5-22 µg/ml) can be achieved using an excess of EDTA with aqueous model salt solutions. An internal standard is not required because a known excess of EDTA is added and the remaining free EDTA can be used to recalculate the quantity of chelated metal cations. The utility of the method is demonstrated for the analysis of divalent cations in some food supplements and in pharmaceutical products.

Accumulation Pattern of Inorganic Elements in Scaly Tooth Mushroom (Sarcodon imbricatus) from Northern Poland.

Several studies have documented contamination levels and daily intake of metallic elements from foodstuffs including rice, maize, pulses, vegetables, fruits, fish, meat, egg, milk etc., however, limited literature is available on metal contamination levels in wild growing mushrooms and possible human exposure via consumption of it. Sarcodon imbricatus is an edible mushroom, commonly consumed in many parts of the world. Very few studies have been conducted on inorganic elemental composition in fruiting bodies (edible part) of this fungus. In this study, elements such as silver (Ag), aluminum (Al), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co,) chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), phosphorous (P), lead (Pb), rubidium (Rb), strontium (Sr) and zinc (Zn) were measured in caps and stems of fruiting bodies of S. imbricatus collected from the Wdzydze forests in Central and the Augustowska Primeval forest in Eastern Poland. Results revealed that a wide variation in concentrations of various metals in caps and stems samples collected from the two forests. Toxic metallic elements such as Cd and Hg showed preferential accumulation in caps than stems samples from both the forests. However, the concentrations of Cd, Hg and Pb in the mushroom samples were below the established weekly intake tolerance limits.

Determination of inorganic cations in biological fluids using a hybrid capillary electrophoresis device coupled with contactless conductivity detection.

We describe the assembly of a hybrid electrophoresis device that contains fused silica capillaries interconnected to a microfabricated interface in a cross format for the determination of inorganic cations in biological samples. The sample transport in the proposed hybrid device was performed under gated injection mode and the separations were monitored with a capacitively coupled contactless conductivity detector. The capillary extremities were inserted into polypropylene tubes to create solution reservoirs. Sensing electrodes were produced using stainless-steel hypodermic needles previously cut with 2.0 mm length. The running composition and injection time were optimized and the best results were found using 50 mmol/L lactic acid, 20 mmol/L histidine and 3 mmol/L 18-crown-6 ether, and an electrokinetic injection time of 15 s. The separation of six inorganic cations was achieved with baseline resolution, and efficiencies were between 9.1 × 103 and 5.4 × 104 plates/m. The proposed hybrid device was explored for determining the concentration levels of inorganic cations in urine, saliva, and tear samples, employing Li+ as an internal standard. The achieved results were in good agreement with the data reported in the literature. The reliability of the proposed method ranged from 93 to 98%, thus suggesting satisfactory accuracy for bioanalytical applications.

Voltammetric Mechanism of Multiion Detection with Thin Ionophore-Based Polymeric Membrane.

The capability to detect multianalyte ions in their mixed solution is an important advantage of voltammetry with an ionophore-based polymeric membrane against the potentiometric and optical counterparts. This advanced capability is highly attractive for the analysis of physiological ions at millimolar concentrations in biological and biomedical samples. Herein, we report on the comprehensive response mechanisms based on the voltammetric exchange and transfer of millimolar multiions at a thin polymeric membrane, where an ionophore is exhaustively depleted upon the transfer of the most favorable primary ion, I(zI). With a new voltammetric ion-exchange mechanism, the primary ion is exchanged with the secondary favorable ion, J(zJ), at more extreme potentials to transfer a net charge of |zJ|/nJ - |zI|/nI for each ionophore molecule, which forms 1:nI and 1:nJ complexes with the respective ions. Alternatively, an ion-transfer mechanism utilizes the second ionophore that independently transfers the secondary ion without ion exchange. Experimentally, a membrane is doped with a Na(+)- or Li(+)-selective ionophore to detect not only the primary ion, but also the secondary alkaline earth ion, based on the ion-exchange mechanism, where both ions form 1:1 complexes with the ionophores to transfer a net charge of +1. Interestingly, the resultant peak potentials of the secondary divalent ion vary with its sample activity to yield an apparently super-Nernstian slope as predicted theoretically. By contrast, the voltammetric exchange of calcium ion (nI = 3) with lithium ion (nJ = 1) by a Ca(2+)-selective ionophore is thermodynamically unfavorable, thereby requiring a Li(+)-selective ionophore for the ion-transfer mechanism.

Fluorescent probes and bioimaging: alkali metals, alkaline earth metals and pH.

All living species and life forms have an absolute requirement for bio-functional metals and acid-base equilibrium chemistry owing to the critical roles they play in biological processes. Hence, a great need exists for efficient methods to detect and monitor biometals and acids. In the last few years, great attention has been paid to the development of organic molecule based fluorescent chemosensors. The availability of new synthetic fluorescent probes has made fluorescence microscopy an indispensable tool for tracing biologically important molecules and in the area of clinical diagnostics. This review highlights the recent advances that have been made in the design and bioimaging applications of fluorescent probes for alkali metals and alkaline earth metal cations, including lithium, sodium and potassium, magnesium and calcium, and for pH determination within biological systems.

Metal-ion-specific screening of charge effects in protein amide H/D exchange and the Hofmeister series.

In this study, protein charge ladders and mass spectrometry were used to quantify how metal cations in the Hofmeister series (Na(+), K(+), Li(+), Mg(2+), and Ca(2+)) permute the effects of lysine acetylation on the rate of amide H/D exchange in a representative protein (myoglobin, Mb). The successive acetylation of up to 18 Lys-ε-NH3(+) groups in Mb caused a linear decrease in its global rate of amide H/D exchange (as measured by mass spectrometry), despite also decreasing the thermostability of Mb by >10 °C. The ability of a metal cation to screen kinetic electrostatic effects during H/D exchange-and to abolish the protective effect of acetylation against H/D exchange-was found to depend on the position of the cation in the Hofmeister series. Na(+) and K(+) cations did not fully equalize the rates of H/D exchange among each "rung" of the charge ladder, whereas Mg(2+) and Ca(2+) did equalize rates without eliminating the hydrophobic core of the protein (i.e., without unfolding Mb); Li(+) exhibited intermediate effects. The ability of Mg(2+) and Ca(2+) to completely screen electrostatic effects associated with the H/D exchange of charge isomers of Mb suggests that Mg(2+) or Ca(2+) (but not Na(+) or K(+)) can be used to quantify the magnitude by which electrostatic charge contributes to the observed rates of amide H/D exchange in proteins.

Alkali and alkaline earth elements in follicular fluid and the likelihood of diminished ovarian reserve in reproductive-aged women: a case‒control study.

BACKGROUND: Imbalances in alkali elements (AEs) and alkaline earth elements (AEEs) cause reproductive disorders. However, it remains unclear whether AEs/AEEs in follicular fluid have a relationship with the serious reproductive disorder known as diminished ovarian reserve (DOR). METHODS: A nested case‒control study was carried out in China. Follicular fluid samples from 154 DOR patients and 154 controls were collected and assessed for nine AEs/AEE levels. Both the mixed and single effects of the elements on DOR were estimated with a Bayesian kernel machine (BKMR) and logistic regressions. RESULTS: The DOR group had higher median concentrations of Li, Na, and K in follicular fluid (all P values < 0.05). The logistic regression showed that compared with their lowest tertile, the high tertiles of K [OR:2.45 (1.67-4.43)], Li [OR: 1.89 (1.06-3.42)], and Cs [OR: 1.97 (1.10-3.54)] were significantly associated with the odds of DOR. The BKMR model reported that the DOR likelihood increased linearly across the 25th through 75th percentiles of the nine-AE/AEE mixture, while the AE group contributed more to the overall effect. CONCLUSION: This study revealed an association in which the likelihood of DOR increased with higher overall concentrations of AE/AEEs in follicular fluid. Among the nine detected elements, K, Li, and Cs exhibited significant individual associations with DOR. We provide new clues for the environmental factors on female fertility decline. TRIAL REGISTRATION: Retrospectively registered.

The evolutionary ecology of dwarfism in three-spined sticklebacks.

1. Body size is a defining phenotypic trait, but the ecological causes of its evolution are poorly understood. Most studies have considered only a single putative causal agent and have failed to recognise that different environmental agents are often correlated. 2. Darwin suggested that although trait variation across populations is often associated with abiotic variation, evolution is more likely to be driven by biotic factors correlated with the abiotic variation. This hypothesis has received little explicit attention. 3. We use structural equation modelling to quantify the relative importance of abiotic (pH, metal concentrations) and biotic (competition, predation) factors in the evolution of body size in three-spined sticklebacks Gasterosteus aculeatus on the island of North Uist, Scotland. We combine phenotypic data from multiple isolated populations, detailed characterisation of their environment and a common garden experiment that establishes the genetic basis of size differences. 4. Three-spined sticklebacks on North Uist show almost unprecedented intraspecific evolution of body size that has taken place rapidly (<16,000 years). The smallest fish mature at only 7% of the mass of ancestral, anadromous fish. Dwarfism is associated with reduced abundance of a smaller competitor species, the nine-spined stickleback Pungitius pungitius, and with low pH indicative of poor resource conditions. Dwarfism also tends to occur where an important predator, the brown trout Salmo trutta, is also small. The abundance of P. pungitius and the size of S. trutta are themselves related to underlying abiotic environmental variation. 5. Despite the close association between abiotic and biotic factors across populations, our results support Darwin's hypothesis that biotic factors, associated with variation in the abiotic environment, are more important in explaining evolution than is abiotic variation per se. This study demonstrates the importance of considering the relationships between environmental variables before conclusions can be drawn about the causes of (body size) evolution on islands.

Sensitive analysis of metal cations in positive ion mode electrospray ionization mass spectrometry using commercial chelating agents and cationic ion-pairing reagents.

Metals play a very important role in many scientific and environmental fields, and thus their detection and analysis is of great necessity. A simple and very sensitive method has been developed herein for the detection of metals in positive ion mode ESI-MS. Metal ions are positively charged, and as such they can potentially be detected in positive ion mode ESI-MS; however, their small mass-to-charge (m/z) ratio makes them fall in the low-mass region of the mass spectrum, which has the largest background noise. Therefore, their detection can become extremely difficult. A better and well-known way to detect metals by ESI-MS is by chelating them with complexation agents. In this study eleven different metals, Fe(II), Fe(III), Mg(II), Cu(II), Ru(III), Co(II), Ca(II), Ni(II), Mn(II), Sn(II), and Ag(I), were paired with two commercially available chelating agents: ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS). Since negative ion mode ESI-MS has many disadvantages compared to positive ion mode ESI-MS, it would be very beneficial if these negatively charged complex ions could be detected in the positive mode. Such a method is described in this paper and it is shown to achieve much lower sensitivities. Each of the negatively charged metal complexes is paired with six cationic ion-pairing reagents. The new positively charged ternary complexes are then analyzed by ESI-MS in the positive single ion monitoring (SIM) and single reaction monitoring (SRM) modes. The results clearly revealed that the presence of the cationic reagents significantly improved the sensitivity for these analytes, often by several orders of magnitude. This novel method developed herein for the detection of metals improved the limits of detection (LODs) significantly when compared to negative ion mode ESI-MS and shows great potential in future trace studies of these and many other species.

Investigation of chocolate types on the content of selected metals and non-metals determined by ICP-OES analytical technique.

Chocolate, one of the most popular sweets in the world, is consumed by people of all ages. Available data point to significant increases in consumption and production. However, successful determination of elements in chocolate is still difficult because of the characteristics of the matrix which contains a high content of organic compounds, like hydrogenated vegetable oil, vegetable fats, solids from malt extract, salts, emulsifiers, etc., causing problems with appropriate decomposition or digestion of sample. In this study, chocolate samples were prepared according to two procedures: water bath and microwave-assisted mineralisation. The use of Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) allowed us to determine the elemental composition of dark, milk, and white chocolate bars available on the Polish market as well as a cacao sample (100% cocoa powder). The elements assessed were Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Sr, and Zn. The obtained results were used to compare the effectiveness of sample pre-treatment methods and to assess the correlation between the concentrations of specific elements and type of chocolate by the application of chemometric and statistical tools. The research showed that levels of analysed macro- and microelements are directly connected with the type of chocolate, characterised by the variable contents of cocoa paste and added milk. Data for all samples after mineralisation shown that among macroelements P was the most abundant, followed by Mg, Ca, Na, K, and S. The major essential element with the highest level was Fe, followed by Zn and Cu. In the group of toxic metals the highest content was obtained for Ba, then Al and Sr, but none exceeded permissible values prepared by health benefit organisations.

Influence of normal tide and the Great Tsunami as recorded through hourly-resolution micro-analysis of a mussel shell.

We report here hourly variations of Mg/Ca, Sr/Ca, and Ba/Ca ratios in a Mediterranean mussel shell (Mytilus galloprovincialis) collected at the Otsuchi bay, on the Pacific coast of northeastern Japan. This bivalve was living in the intertidal zone, where such organisms are known to form a daily or bidaily growth line comprised of abundant organic matter. Mg/Ca ratios of the inner surface of the outer shell layer, corresponding to the most recent date, show cyclic changes at 25-90 µm intervals, while no interpretable variations are observed in Sr/Ca and Ba/Ca ratios. High Mg/Ca ratios were probably established by (1) cessation of the external supply of Ca and organic layer forming when the shell is closed at low tide, and (2) the strong binding of Mg to the organic layer, but not of Sr and Ba. Immediately following the great tsunami induced by the 2011 Tohoku earthquake, Mg/Ca enrichment occurred, up to 10 times that of normal low tide, while apparent Ba/Ca enrichment was observed for only a few days following the event, therefore serving a proxy of the past tsunami. Following the tsunami, periodic peaks and troughs in Mg/Ca continued, perhaps due to a biological memory effect as an endogenous clock.

Element profiles in blood and teeth samples of children with congenital heart diseases in comparison with healthy ones.

BACKGROUND: Some elements were claimed to play a role in the pathogenesis of congenital heart defects (CHD) and influence the general well-being and health of these children. OBJECTIVES: We aimed to assess the levels of some elements simultaneously in the blood and teeth samples of children with cyanotic and acyanotic CHD compared with healthy children. METHODS: A total of 39 children with CHD (11 with cyanotic and 28 with acyanotic CHD) and 42 age- and sex-adjusted controls were enrolled. Levels of 13 elements, including magnesium, phosphorus, calcium, chromium, manganese, iron, copper, zinc, strontium, cadmium, lead, mercury, and molybdenum, were assessed using inductively coupled plasma mass spectrometry. RESULTS: Children with cyanotic and acyanotic CHD had significantly lower teeth calcium and calcium/phosphorus ratio as compared to the controls after adjusting for confounders. The mean blood iron level was found to be significantly higher in the cyanotic CHD group compared to the other groups. In addition, children with acyanotic CHD had significantly higher teeth copper levels, higher blood molybdenum and lower blood magnesium levels compared to the healthy control group. Blood cadmium and mercury levels were found to be significantly elevated in both the cyanotic and acyanotic CHD groups compared to the healthy control group. There were no differences in toxic metal levels of teeth in cases with CHD. CONCLUSION: Monitoring adequate and balanced gestational micronutrient intake might support not only maternal health but also fetal cardiac development and infant well-being. Supplementation of magnesium should be evaluated in patients having CHD.

Logging residue removal after thinning in boreal forests: long-term impact on the nutrient status of Norway spruce and Scots pine needles.

The aim of this study was to compare how conventional stem harvesting (CH) and whole-tree harvesting (WTH) in the first, and in some cases also in the second, thinning affect the needle nutrient status of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands in Finland. A series of 12 long-term field experiments was studied. The experiments were established during 1978-86. The effects of logging residue removal after thinnings on the needle nutrient concentrations were generally minor and without any overall trends, but there were differences between experiments. Trees tend to maintain their current needle nutrient concentrations at the same level by re-utilizing the nutrients stored in the older tissues and by changing C allocation in the whole tree. Thus, needle analysis should be combined with stem growth data in order to achieve a more comprehensive understanding of the effects of WTH on the nutrient status of trees.

Inter-relationship between elements in human hair: The effect of gender.

The aim of the present work was to examine the inter-relationship between elements in human hair depending on gender. In the whole population, the following groups of correlated elements were identified: alkaline earth metals (Ba, Ca, Mg, Sr), major microelements (Cu, Mn, Si, Zn) and La, Ti. In the subpopulation of males, the (Ag, Al, As, Fe) group was additionally included, whereas in the group of females (Ag, Al, Fe, Zr) was included. The group of alkali metals (Li, Na, K) and P was particularly visible in the group of males. In the group of females correlations among (Al, Co, Fe, K, Ti) were stronger than in males. In both sexes correlations between Mo, B and V (in females additionally Bi was present) and Bi-Co were found. Only in hair of males (Cd, Fe, Mn) and (Cu, Na, P) were detected, and the group of (As, Co, Cr, Fe, K, Ti) was detected only in females.

Bioactive indicators related to bioelements of eight unifloral honeys.

Honey is the most popular bee product used by man, with nutritional and medicinal purposes. Its great diversity is attributed to numerous factors (bee type, visited flora, environment, and management). The quality of honey is controlled with routine parameters (free acidity, diastase activity, reducing sugars, ash, water, hydroxymethyfurfural, and sucrose contents). Besides the biochemical quality control, a functional profile is also important for pharmacological applications. In this work, bioactive indicators such as the antioxidant activity, flavonoid and polyphenol contents were evaluated by spectrophotometry, and correlated to the content of six bioelements (Ca, Cu, Fe, Mg, Mn, Zn) measured by atomic absorption spectroscopy, tandem FI-FAAS, in 14 unifloral Czech honeys. The antioxidant activity was 43.13 +/- 53.72 micromoles TEAC/100 g honey. The flavonoid content was 5.18 +/- 4.19 mg QE/100 g, and the polyphenol content was 45.38 +/- 27.20 mg GAE/100 g. Buckwheat honey showed the highest values for these indicators of bioactivity, the acacia honeys the lowest, and the rest of the honeys were comprised between both of them. Honey content of bioelements was 138.19 +/- 55.57 ppm Ca (min 77.11-max 261.65), 0.33 +/- 0.41 ppm Cu (min 0.00-max 1.37), 2.95 +/- 1.10 ppm Fe (min 1.34-max 5.36), 35.08 +/- 29.59 ppm Mg (min 8.76-128.06), 4.93 +/- 3.99 ppm Mn (min 0.34-max 11.31), 1.07 +/- 0.56 ppm Zn (min 0.49-max 2.52). The antioxidant activity of honey was significantly correlated to its content of cupper, iron, magnesium, manganese and zinc, but was not correlated to calcium.

The non-covalent complexes of α- or γ-cyclodextrin with divalent metal cations determined by mass spectrometry.

Noncovalent complexes between cyclodextrin (CD) and divalent metal cations drew growing attentions due to their applications in the pharmaceutical industry for molecular recognition. In this study, gas-phase binding of noncovalent complexes between α-, or γ-CD and divalent metal cations was investigated by electrospray ionization mass spectrometry (ESI-MS), demonstrating the formation of 1:1 stoichiometric noncovalent complexes. The binding of the complexes were furtherly confirmed by collision-induced dissociation (CID) with tandem mass spectrometry. The CID revealed the fragmentation pattern were strongly dependent on the electronic configuration of the cations and the charge separation reaction frequently took place in the cyclodextrin-complexes with transition metal cations. For the non-covalent complexes of α-CD with Mg2+, Ca2+, Sr2+ or Ba2+ at a collision energy of 25 eV, the fragments attributed to [α-CD + cation-nGlucose unit]2+ were observed (named series A). However, for the γ-CD complexes with transition metal cations Co2+, Ni2+, Cu2+ or Zn2+, apart from fragments of series A, it were observed fragment ions of [γ-CD + cation-nGlucose unit]+ (named series B), together with the Glucose unit (m/z 163.2) and its products with loss of H2O (m/z 145.2 and 126.8). The CID performed at a collision energy from 10 to 50 eV showed that the binding strength of complexes increase in the order of [α-CD + Mg]2+, [α-CD + Ca]2+, [α-CD + Sr]2+ and [α-CD + Ba]2+. Through mass spectrometric titrations, the values of dissociation constant Kd (in µmol•L-1) for the complexes of α-CD with Ca2+ or Ni2+ were obtained, which were 4.30 and 4.26, respectively.

Combining Multi-Element Analysis with Statistical Modeling for Tracing the Origin of Green Coffee Beans from Amhara Region, Ethiopia.

Characterization of coffee terroirs is important to determine authenticity and provide confidence for consumers to select the right product. In this regard, Amhara Region, which is located at the northwestern part of Ethiopia, produces various local coffee types with distinct cup qualities. The coffees are, however, not yet registered with certification marks or trademarks for indications of their geographical origins. This study was aimed at developing analytical methodology useful to determine the geographical origin of green coffee beans produced in Amhara Region based on multi-element analysis combined with multivariate statistical techniques. For this, a total of 120 samples of green coffee beans, collected from four major cultivating zones (West Gojjam, East Gojjam, Awi, and Bahir Dar Especial Zones) were analyzed for K, Mg, Ca, Mn, Fe, Cu, Fe, Co, Ni, Zn, Si, Cr, Cd, and Pb using inductively coupled plasma-optical emission spectroscopy. The elemental analysis data were subjected to principal component analysis (PCA) and linear discriminant analysis (LDA). PCA was used to explore the natural groupings of samples and the discriminatory ability of elements. Accordingly, the elements K, Mg, Ca, and Na were found to be the main discriminators among samples. LDA provided a model to classify the coffee samples based on their production zones with an accuracy of 94.2% and prediction ability of 93.4%. Thus, the elemental composition of green coffee beans can be used as a chemical descriptor in the authentication of coffee produced in Amhara Region.

Could biological tissue preservation methods change chemical elements proportion measured by energy dispersive X-ray spectroscopy?

Energy dispersive X-ray spectroscopy (EDS) is a powerful technical tool used in the biomedical field to investigate the proportion of chemical elements of interest in research, such as heavy metal bioaccumulation and the enzymatic cofactors and nanoparticle therapy in various pathologies. However, the correct evaluation of the proportion of the elements is subject to some factors, including the method of sample preservation. In this study, we seek to investigate the effect of biological tissue preservation methods on the proportion of chemical elements obtained by the EDS methodology. For such, we used EDS to measure the proportion of chemical elements with biomedical interest in preserved livers, using three common methods for preserving biological tissues: (a) freezing, (b) paraformaldehyde fixative solution, and (c) Karnovsky solution. We found an increased level of sodium and reduced contents of potassium and copper in samples fixed in fixative solutions, when compared to frozen samples (p < 0.05). Our data indicate that preservation methods can change the proportion of chemical elements in biological samples, when measured by EDS. Frozen preservation should be preferred to retain the actual chemical content of samples and allow a correct assessment of the proportion of their elements.

Spectral analysis of Miracle Moringa tree leaves using X-ray photoelectron, laser induced breakdown and inductively coupled plasma -optical emission spectroscopic techniques.

The antioxidant Moringa oleifera (a medicinal plant) leaves (MOLs) containing diverse nutrients are highly beneficial for the human health. The MOLs upon consumption can lower the blood sugar, cure the heart diseases, and reduce the inflammation. In this perception, the "primary nutrients contents" in the dry MOLs (pellet samples) were evaluated for the first time using the XPS, LIBS and ICP-OES techniques. The XPS analysis of the MOLs showed the presence of vital elements like calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), phosphorous (P), sulfur (S) and zinc (Zn). The LIBS analyses of the MOLs revealed the atomic and ionic spectral lines corresponding to the essential nutrients such as the Ca, Na, K, Fe, Mg, Mn, Cu, P, S and Zn. The calibration free LIBS algorithm (CF-LIBSA) was developed to quantify the content of each element in the dry MOLs. In addition, the LIBS results were validated by the analysis using ICP-OES standard analytical technique. The elemental contents in the MOLs obtained from the CF-LIBS analyses were counter verified by the ICP-OES results. Present results are highly valuable for the development of a traditional herbal medicine using the miracle MOLs.