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Propolis tinctures are popular alternative medicines, but mandatory labeling requirements relating to the inorganic content or percentage of ethanol are absent. Knowing the elemental content is useful for quality assurance/quality control of the tinctures between batches, as well as the safety of the products for consumers. Microwave plasma – atomic emission spectrometry (MP-AES) is a relatively low-cost, robust, multielemental technique that can analyze ethanolic extracts of propolis following minimum sample preparation. However, there are no published papers using MP-AES for this application. The technique was evaluated for the determination of sixteen elements in lab-made preparations and in 23 products from markets in Mexico. The matrix effects of the ethanol content of the samples were also evaluated and were found to affect the detection limit of some elements. There was high variability in the elemental composition of the major (K, Fe, Mg, and Na) and minor (Al, Cd, Co, Cr, Cu, Mn, Ni, and Zn) elements among the samples. The median concentrations of cadmium, and lead in the propolis tinctures were below 0.28 µg·L−1 and 2.8 µg·L−1, respectively. [ABSTRACT FROM AUTHOR]

The bis[2‐(1H‐benzimidazol‐2‐yl)phenyl]disulfide [bis(2phSbz)] was characterized by SEM, nitrogen adsorption and desorption, PXRD, and TGA analysis. It was evaluated as a solid chelating adsorbent to remove lead(II), cadmium(II), and zinc(II) ions from aqueous solutions. Bis(2phSbz) consists of agglomerated, rectangular particles of non‐uniform size, lacking porosity and roughness. Metal ion sorption is pH dependent. The equilibrium data are described by the Langmuir model, while the pseudo‐second‐order model fits metal ions′ adsorption kinetics best. The maximum adsorption capacities for lead(II), cadmium(II), and zinc(II) were 543.82, 482.56, and 306.96 mg/g, respectively. In a competitive test, bis(2phSbz) was found to be able to selectively remove lead(II) from multicomponent solutions. Desorption efficiencies higher than 65 % can be achieved using EDTA 0.1 M as a desorption agent. From a theoretical standpoint, we corroborate the experimental results in terms of some significant quantum mechanics descriptors. Bis(2phSbz) may be a novel and potentially valuable chelating adsorbent for lead(II) removal. [ABSTRACT FROM AUTHOR]

Leucaena leucocephala is a potential source of polyphenols widely available in southern Mexico. This work highlights the extraction of polyphenols from Leucaena leucocephala leaves waste (LLEPs) and the evaluation of their efficiency to remove the single and multicomponent Pb(II) and Cd(II) metal ions from aqueous solutions. Batch test conditions were carried out to examine the effects of contact time, initial metal ion concentration, and adsorbent dosage on the biosorption process. The surface textures and the composition of the LLEP biosorbent was characterized using pH of point of zero charge (pHPZC), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry, respectively. Further analysis using ATR-FTIR after adsorption contact of biosorbent was also investigated. The highest Langmuir saturation monolayer adsorption capacity, qm, for the removal of Pb(II) by LLEPs was obtained as 25.51 and 21.55 mg/g in mono- and bimetal solutions, respectively. The pseudo-second-order model provided the best fit for the kinetic data obtained for the removal of Pb(II), Cd(II), and their mixture, and the k2 values depend on the adsorbent mass. This implied that the chemisorption process might be the mechanism of the solute ions-LLEPs interaction in this study. Furthermore, nearly 100% removal of lead and cadmium individually and 95% of their mixture was found using 0.9 g of LLEPs. [ABSTRACT FROM AUTHOR]