A novel and selective sorbent for micro-solid phase extraction was synthesized by chemical functionalization of graphene oxide with glycine. The structure of this nanomaterial, referred to as GO-Gly, was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. GO-Gly was used for preconcentration of chromium, zinc, and copper ions from water samples prior to their determination by energy dispersive X-ray fluorescence spectrometry (EDXRF). The proposed procedure is based on dispersion of micro amounts of GO-Gly in aqueous samples. After adsorption of metal ions on its surface, samples were filtered under vacuum and then membrane filters were directly submitted to energy dispersive X-ray fluorescence spectrometric measurements. In order to obtain optimal preconcentration conditions, some parameters affecting sorption process, such as pH, amount of GO-Gly, sorption times, and sample volume, were examined. Under optimal conditions the calibration curves were linear in a 1–150 ng mL⁻¹ range with recoveries higher than 97%. The obtained detection limits for Cr(III), Zn(II), and Cu(II) determinations are 0.15, 0.07, and 0.08 ng mL⁻¹, respectively. A relative standard deviation of the proposed procedure (at a 10 ng mL⁻¹ level for n = 10) is lower than 2.3%. The proposed method was successfully applied for determination of Cr(III), Zn(II), and Cu(II) ions in water samples.

Non-monotonic changes in the static and dynamic properties of a series of phenyl alcohols were assigned to the interplay between the dispersive forces and H-bonding interactions.

In this paper, catalyzed and non-catalyzed water-initiated Ring-Opening Polymerization (ROP) of ε-caprolactone (ε-CL) under various thermodynamic conditions (T = 293–393 K and p = 0.1–500 MPa) was carried out. As organocatalysts, two non-nucleophilic bases characterized by different modes of action, i.e. 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), were used. High-pressure experiments revealed that polymerization proceeded much faster with respect to the reactions performed at ambient pressure (a limiting example of t = 168 h vs. t = 6 h) and the synthesized PCLs were characterized by molar masses, M_n, up to 16.7 kg mol⁻¹ and low/moderate dispersity, Đ = 1.03–1.56. Moreover, as revealed by MALDI-TOF studies, polymers with telechelic characters were obtained. In each case the varying content of cyclic polyesters was detected as well. Their presence had a strong influence on the discrepancy between theoretically and experimentally determined M_n. Collected data surprisingly also revealed the enhanced catalytic activity of DBU over TBD at high pressure. One can add that for the ROP catalyzed by the latter compound, the termination process was still observed, while for a selected monomer to catalyst ratio a “pseudo-living” character of polymerization was warranted for the former catalyst. Further investigations with the use of FT-IR allowed us to hypothesize that TBD is fully protonated by water that is followed by cluster formation limiting its catalytic activity. On the other hand, the enhanced activity of DBU results from the presence of both forms (protonated and non-protonated) in reaction media acting as a Brønsted acid/base system. Our studies offer a new, more eco-friendly way to synthesize well-defined telechelic PCLs of moderate molecular weights in very short times and a better understanding of the role of intermolecular interactions in the catalytic activity of organocatalysts and generally the progress of ROP.