Application of X-ray powder diffraction for analysis of selected dietary supplements containing magnesium and calcium

It is estimated that ∼50% of medications and dietary supplements offered in the Internet are counterfeit. X-ray diffraction is one of the techniques which may be successfully applied to identify various chemical compounds in polycrystalline mixtures such as dietary supplements, but also medications, narcotics or designer drugs. X-ray diffraction enables the understanding of compositions of such mixtures. For the tests, 22 dietary supplements which should contain magnesium and calcium compounds, available in pharmacies, groceries, Internet shops, as well as in shops for sportspersons, were selected. Identification of crystalline substances present in the tested sample consists in determination of inter-planar distances dhkl of investigated substances and determination of intensity of the obtained diffraction lines, and then in comparing them with values contained in diffraction databases. In this study, the ICDD-PDF2 database was used. The most important criterion in qualitative analysis, confirming the presence of a given phase, is the conformity of positions of diffraction lines in the recorded diffraction image with those in the reference image. Reflection shifts for the individual 2θ angles compared with the data from the database should not exceed 0.2◦. In most cases, X-ray analysis of the investigated dietary supplements proved the presence of magnesium and calcium compounds declared by themanufacturer, as well as allowing the identification of auxiliary substances present in the tested products. In the case of two magnesium-containing dietary supplements, the magnesium compounds declared by the manufacturer were not found. Our studies confirmed the effectiveness of X-ray structural analysis and proved the possibility of distinguishing counterfeit preparations from authentic products, as well as to use this method for the quality control of such pharmaceutical preparations

Genesis of iron and manganese sediments in Zoloushka Cave (Ukraine/Moldova) as revealed by δ13C organic carbon

Zoloushka Cave is one of the largest maze gypsum caves in the world. Mining of the gypsum bedrock and lowering of the water level due to the pumping of groundwater led to exposure of the cave passages to vadose conditions and changed the hydrochemistry of the karst water. As a result, large quantities of Fe and Mn hydroxides were deposited in the passages. It was found that at least two groups of various organisms were involved in depositing ferrous and manganese sediments. In order to establish the mechanism of deposition, we conducted chemical analyses of the sediments and isotopic analyses of organic carbon. This enabled us to formulate a hypothetical model of the biogenic deposition of Fe and Mn compounds. According to the model, autotrophic iron bacteria precipitated Fe hydroxides. Organisms of this type assimilate CO2 from cave atmospheres and, as a result of isotopic fractionation during that process, organic matter in 13C is depleted by 7.3‰ relative to CO2. Heterotrophic bacteria (responsible for depositing manganese oxides) parasitise on autotrophic bacteria without changing the carbon isotope composition of organic matter. Fungal organisms living in ferrous sediments separate carbon from organic matter, resulting in enrichment with the heavier carbon isotope by 2‰

Application of X-ray powder diffraction and differential scanning calorimetry for identification of counterfeit drugs

X-ray analysis confirmed that in all investigated samples, the active API (acetylsalicylic acid and ascorbic acid) was present. The values of the interplanar distance dhkl for the studied samples are in good accordance with those presented in the ICDD database. The intensities of the diffraction lines depend on the content of the component in the tested preparation. Therefore, different intensities of lines for the APIs were observed in the obtained diffraction patterns. Thermal analysis of the studied substances showed that during the thermal analysis, the following phenomena might occur: dehydration and (or) melting, crystalline transformation. Moreover, it was found that the chemical structure of the studied compounds affects the process of their thermal decomposition. The data obtained during these investigations can be useful in quick tests of physicochemical discrepancies and abnormalities between potential components of pharmaceutical preparations. The evidence for the interaction can be obtained by comparing DSC and TG curves of the drug and the excipient, as well as those of their physical mixtures. For this reason, the study of characteristics of thermal decomposition of drugs and excipients is necessary. Based on the above investigations, it may be stated that a combination of two methods: XRPD and DSC can be used to distinguish the original drugs from counterfeit products, e.g., by checking for the presence of the correct API or by a comparison of the drugs fingerprint

The Mossbauer and x-ray studies of the spinel ferrites Cu0.5Fe0.8Cr2Se4 prepared by the ceramic method

Seleno-spinels with nominal chemical composition Cu0:5Fe0:5Cr2Se4 and Cu0:2Fe0:8Cr2Se4 were prepared as polycrystalline samples using ceramic method. The assumed composition was verified by wavelength-dispersive X-ray °uorescence spectrometry. The X-ray analysis was carried out in order to make phase analysis and to compare its results with those obtained with the Mossbauer spectroscopy

Electrical and magnetic studies of ZnxMnyCr zSe4 p-type semiconductors

The structural, electrical and magnetic investigations carried out on the ZnxMnyCrzSe4 polycrystals with y = 0:19, 0.29 and 0.38 revealed the spinel structure with the Mn ions occupying tetrahedral sites, p-type conduction with polaronic transport at high temperatures and antiferromagnetic order with a Néel temperature of 20 K and a Curie–Weiss temperature of 103 K. With increasing Mn content in a sample both the effective magnetic moment and the re-entrant temperature increase while the first and second critical fields connected with a metamagnetic transition and the breakdown of the conical spin arrangement decrease, respectively. These results are interpreted in terms of giant cubic anisotropy as well as an effect of Mn impurities on the screw structure of ZnCr2Se4

The Mossbauer spectroscopy and analytical investigations of the polycrystaline compounds with general formula ZnxSnyCr2Se4

We present combined X-ray powder diffraction and Mossbauer 119Sn studies of polycrystalline compounds with a general formula ZnxSnyCrzSe4 (where x + y + z ¼ 3). The obtained single-phase compounds crystallize in the spinel cubic structure | Fd3m. Tin ions are found to occupy both tetrahedral and octahedral sublattices. On the contrary to the strong tetrahedral site preference energy of Sn, the presented data strongly suggest that the increase in lattice parameters with Sn doping is caused by Sn ions that incorporated into octahedral positions. A quadrupole and isomer shifts of 119Sn in (SnSe4)6¡ and (SnSe6)4¡ are also reported

Effect of cation substitution on critical fields in the n-type Zn xSnyCrzSe4 spinel semiconductors

The ac dynamic magnetic susceptibility was used to study a cation substitution on critical fields in polycrystalline (Zn0:87Sn0:048)Cr2:02Se4 and Zn0:93[Cr1:95Sn0:05]Se4 spinels with tetra- and octahedral coordination of Sn ions, respectively. An increasing static magnetic field shifts the Néel temperature TN to lower temperatures while a susceptibility peak at Tm in the paramagnetic region — to higher temperatures. Below TN the magnetic field dependence of susceptibility, Âac(H), shows two peaks at critical fields Hc1 and Hc2. The values of Hc1 decrease slightly with temperature while the values of Hc2 decrease strongly with temperature, especially for spinel with octahedral coordination of Sn ions, suggesting a weakness of the ferromagnetic component

X-ray and thermal analysis of selected drugs containing acetaminophen

Studies carried out by X-ray and thermal analysis confirmed that acetaminophen (paracetamol), declared by the manufacturers as an Active Pharmaceutical Ingredient (API), was present in all studied medicinal drugs. Positions of diffraction lines (2θ angles) of the studied drugs were consistent with standards for acetaminophen, available in the ICDD PDF database Release 2008.ID2θI values were lower than 0.2°, confirming the authenticity of the studied drugs. Also, the values of interplanar distances dhkl for the examined samples were consistent with those present in the ICDD. Presence of acetaminophen crystalising in the monoclinic system (form I) was confirmed. Various line intensities for API were observed in the obtained diffraction patterns, indicating presence of the preferred orientation of the crystallites in the examined samples. Thermal analysis of the studied substances confirmed the results obtained by X-ray analysis. Drugs containing only acetaminophen as an API have melting point close to that of pure acetaminophen. It was found that presence of other active and auxiliary substances affected the shapes and positions of endothermal peaks significantly. A broadening of endothermal peaks and their shift towards lower temperatures were observed accompanying an increase in the contents of additional substances being “impurities” in relation to the API. The results obtained by a combination of the two methods, X-ray powder diffraction (XRPD) and differential scanning calorimetry/thermogravimetry (DSC/TGA), may be useful in determination of abnormalities which can occur in pharmaceutical preparations, e.g., for distinguishing original drugs and forged products, detection of the presence of a proper polymorphic form or too low content of the active substance in the investigated drug

Photosynthesis-inhibiting activity of N-(Disubstitutedphenyl)-3- hydroxynaphthalene-2-carboxamides

A set of twenty-four 3-hydroxynaphthalene-2-carboxanilides, disubstituted on the anilide ring by combinations of methoxy/methyl/fluoro/chloro/bromo and ditrifluoromethyl groups at different positions, was prepared. The compounds were tested for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. N-(3,5-Difluorophenyl)-, N-(3,5-dimethylphenyl)-, N-(2,5-difluorophenyl)- and N-(2,5-dimethylphenyl)-3-hydroxynaphthalene-2-carboxamides showed the highest PET-inhibiting activity (IC50 ~ 10 M) within the series. These compounds were able to inhibit PET in photosystem II. It has been found that PET-inhibiting activity strongly depends on the position of the individual substituents on the anilide ring and on the lipophilicity of the compounds. The electron-withdrawing properties of the substituents contribute towards the PET activity of these compounds

Microstructure and porosity evolution of the Ti-35Zr biomedical alloy produced by elemental powder metallurgy

In the present study, the structure and porosity of binary Ti–35Zr (wt.%) alloy were investigated, allowing to consider powder metallurgy as a production method for new metallic materials for potential medical applications. The porous Ti–Zr alloys were obtained by milling, cold isostatic pressing and sintering. The pressure during cold isostatic pressing was a changing parameter and was respectively 250, 500, 750 and 1000 MPa. The X-ray diffraction study revealed only the α phase, which corresponds to the Ti–Zr phase diagram. The microstructure of the Ti–35Zr was observed by optical microscopy and scanning electron microscopy. These observations revealed that the volume fraction of the pores decreased from over 20% to about 7% with increasing pressure during the cold isostatic pressing. The microhardness measurements showed changes from 137 HV0.5 to 225 HV0.5