Advanced mass spectrometric methods applied to the study of fate and removal of pharmaceuticals in wastewater treatment

This overview is of analytical methodologies based on gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, applied in environmental monitoring of pharmaceutical residues and their known degradation products. We also consider the ability of time-of-flight (TOF) and quadrupole-TOF instruments to provide sufficiently accurate-mass measurements and full-scan spectra for unequivocal confirmation of target compounds and investigation of their degradation products, which are either known or unknown.

We focus attention on the fate and the behavior of pharmaceutical residues during conventional and advanced wastewater treatments. Wastewater-treatment plants are designed to remove conventional pollutants (e.g., suspended solids and biodegradable organic compounds), but not low concentrations of synthetic pollutants (e.g., pharmaceutically active compounds).

Membrane bioreactor systems represent a new generation of processes that have proved to outperform conventional activated sludge treatment in terms of sludge production and effluent quality. In the past few years, there has been much attention paid to their capability for removing trace organic contaminants from sewage. This review highlights their improved performance in removing pharmaceutical residues from wastewater compared to conventional treatment.     

Photodetachment of zwitterions: probing intramolecular Coulomb repulsion and attraction in the gas phase using mono-decarboxylated pyridinium dicarboxylates. Implications on the mechanism of orotidine 5'-monophosphate decarboxylase

Negative ion photoelectron spectra resulting from the decarboxylation of nine zwitterionic pyridinium dicarboxylates (D(x,y)) are reported. Structural assignments are made on the basis of analogy to the spectra of related species, labeling experiments with (13)C- or (2)H-containing substrates, independent syntheses, and comparison to density functional theory and ab initio (B3LYP and CCSD(T), respectively) results. In some cases, an acid-catalyzed isomerization of the D(x,y)-CO(2) ions was found to take place. Adiabatic detachment energies of the resulting zwitterionic ions were measured and are well reproduced by theory. The relative stabilities of the D(x,y)-CO(2) decarboxylation products are largely determined by their intramolecular electrostatic interactions, which are directly probed by the photoelectron spectra and were analyzed in terms of the resulting Coulombic forces. Expulsion of carbon dioxide from the D(x,y) ions was also used as an electrostatic model to probe the mechanism of the enzyme-catalyzed conversion of orotidine 5'-monophosphate (OMP) to uridine 5'-monophosphate (UMP). It was found that the loss of CO(2) from these zwitterions and from oxygen-protonated OMP is retarded by the presence of an additional anionic group. This suggests that the formation of a zwitterion intermediate in the enzyme-catalyzed transformation of OMP to UMP may have less of an energetic impact than commonly thought and could be a "red herring". If so, the electrostatic stress mechanism proposed by Larsen et al. and Pai, Guo, and co-workers maybe followed.     

Thermal degradation of epoxy-silica organic-inorganic hybrid materials

Degradation kinetics of organic-inorganic hybrid materials based on epoxy resin were investigated by thermogravimetric analysis (TGA). The hybrid materials were prepared from diglycidyl ether of bisphenol A (DGEBA) and 3-glycidyloxypropyltrimethoxysilane (GLYMO) polymerised simultaneously by poly(oxypropylene)diamine (Jeffamine D230). Nanometric level of homogeneity in the hybrids was verified by electron microscopy. Energy of activation of degradation for the hybrids with varying inorganic content, as well as for the unmodified epoxy-amine system, was determined by the isoconversional Kissinger-Akahira-Sunose method, and was found to be significantly higher for the hybrid materials than for the unmodified epoxy-amine system. The degradation process was described by empirical kinetic models. The results indicated that presence of the inorganic network influences the mechanism of degradation of organic phase. Greater thermal stability of hybrid materials was confirmed by other parameters obtained from TGA curves.     

The nature and role of 8-deltacyclyl and 7-isodeltacyclyl cations in solvolytic reactions of parent brosylates

Solvolysis of exo-8-deltacyclyl brosylate proceeds directly through a C(2) delocalized cation to exo-8-deltacyclyl acetate. The solvolysis of the endo epimer presents a more complex picture, reacting via a classical deltacyclyl cation, the nonclassical C(2) delocalized cation, and the isodeltacyclyl cation. The solvolysis of exo-7-isodeltacyclyl brosylate generates the 7-isodeltacyclyl ion and subsequently the C(2) delocalized deltacyclyl cation forming 8-deltacyclyl acetate and exo-7-isodeltacyclyl acetate. The cationic intermediates in these three related reaction manifolds are characterized using density functional methods at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d) and BPW91/6-311+G(3df, 2p)//BPW91/6-31G(d) levels.     

Correlation of Osmotic Coefficient Data for ZnSO4(aq) at 25°C by Various Thermodynamic Models

The available literature data on the osmotic coefficient of ZnSO₄(aq) at 25°C in the molality range from 0.1 to 4.3 mol-kg^–1 and new experimental data from 1.2 to 2.9 mol-kg^–1, at the same temperature, are presented. Selected values of the osmotic coefficient from all the data are analyzed using the Clegg-Pitzer-Brimblecombe model, the extended Pitzer model, and a semiempirical equation comprising a power series in molality added to the Debye-Hückel limiting law. The extended Pitzer equation and the Clegg-Pitzer-Brimblecombe equations give the best results in fitting the osmotic coefficient data. All three models are used to calculate ZnSO₄ activity coefficients at 25°C in dilute solutions (<0.1 mol-kg^–1) for comparison with published values.     

Comparison of two polymeric transition metal complexes with 1,4‐benzenedicarboxylate ions as bridging ligands, [Co(C8H4O4)(C12H8N2)(H2O)] and [Cu(C8H4O4)(C10H9N3)]·H2O

The title complexes, catena‐poly[[aqua(1,10‐phenanthroline‐κ²N,N′)­cobalt(II)]‐μ‐benzene‐1,4‐di­carboxyl­ato‐κ²O¹:O⁴], [Co(C₈H₄O₄)(C₁₂H₈N₂)(H₂O)], (I), and catena‐poly[[[(di‐2‐pyridyl‐κN‐amine)copper(II)]‐μ‐benzene‐1,4‐di­carboxyl­ato‐κ⁴O¹,O^1′:O⁴,O^4′] hydrate], [Cu(C₈H₄O₄)(C₁₀H₉N₃)]·H₂O, (II), take the form of zigzag chains, with the 1,4‐benzene­di­carboxyl­ate ion acting as an amphimonodentate ligand in (I) and a bis‐bidentate ligand in (II). The Co^II ion in (I) is five‐coordinate and has a distorted trigonal–bipyramidal geometry. The Cu^II ion in (II) is in a very distorted octahedral 4+2 environment, with the octahedron elongated along the trans O—Cu—O bonds and with a trans O—Cu—O angle of only 137.22 (8)°.     

A study into the possible homoaromatic nature of some related carbene and cationic intermediates with the potential for transannular interaction

A comparison of the aromatic nature of the cations and carbenes centered at the 8-position of tricyclo[3.2.1.0(2,4)]octane, the 9-position of pentacyclo[4.3.0.0(2,4).0(3,8).0(5,7)]nonane, the 6-position of tricyclo[3.1.1.0(2,4)]heptane, and the 4-position of tetracyclo[3.3.0.0(2,8).0(3,6)]octane has been undertaken. Hybrid density functional theory calculations have been used to examine the geometric, energetic, and magnetic characteristics of each cation, singlet carbene, and triplet carbene. The results shed light on the flexibility of the polycycles to achieve stable intermediates and on the breadth of homoaromaticity.     

Spectrofluorometric method for determination of the total mercury content in environmental samples — Waste waters

A highly selective spectrofluorometric method for the determination of total mercury (Hg) in waste waters is described. Fluorescence quenching of rhodamine B with Hg(II) in the presence of iodide, after a concentration step, is the basis of this sensitive method. All forms of mercury, including organic compounds, are pre-oxidized to ionic mercury by acidic potassium permanganate. The final and complete oxidation is achieved by adding potassium persulphate and heating. Hg(II) was reduced by tin(II) chloride and Hg vapour driven by an air stream into an absorption solution containing potassium permanganate and sulphuric acid, using a closed, recirculating air stream. In this solution fluorescence quenching of rhodamine B at an excitation wavelength of 485 nm and emission wavelength of 586 nm was measured. The recoveries were done by adding 3.0 g Hg/100 ml to each sample before the digestion. It was indicated that the recoveries for determining mercury in waste waters were 98.3%–102.7%. The method gives reliable results down to a concentration of 10 ng Hg/ml waste water.     

Macromolecular Pt(IV) Prodrugs from Poly(organo)phosphazenes

The preparation of novel macromolecular prodrugs via the conjugation of two platinum(IV) complexes to suitably functionalized poly(organo)phosphazenes is presented. The inorganic/organic polymers provide carriers with controlled dimensions due to the use of living cationic polymerization and allow the preparation of conjugates with excellent aqueous solubility but long‐term hydrolytic degradability. The macromolecular Pt(IV) prodrugs are designed to undergo intracellular reduction and simultaneous release from the macromolecular carrier to present the active Pt(II) drug derivatives. In vitro investigations show a significantly enhanced intracellular uptake of Pt for the macromolecular prodrugs when compared to small molecule Pt complexes, which is also reflected in an increase in cytotoxicity. Interestingly, drug‐resistant sublines also show a significantly smaller resistance against the conjugates compared to clinically established platinum drugs, indicating that an alternative uptake route of the Pt(IV) conjugates might also be able to overcome acquired resistance against Pt(II) drugs. In vivo studies of a selected conjugate show improved tumor shrinkage compared to the respective Pt(IV) complex.

     

The natural product content of the selected Cabernet Franc wine samples originating from Serbia: a case study of phenolics

This work aimed to evaluate the content of selected phenolic natural products in the wine samples made of three new Serbian Cabernet Franc clones (Nos. 02, 010 and 012, respectively) and mother vine (used as the relevant standard) during the period 2008–2012. Compared with all other wine samples, the Cabernet Franc wine of the clone No. 010 was found to have the highest total content of polyphenolics (1.85 ± 0.02 g/L) and anthocyanins (178.55 ± 3.75 mg/L). In addition, its Folin–Ciocalteu index (36.86 ± 0.12) stood out among the examined samples. Finally, the same wine was enriched with ellagic and gallic acids (3.44 ± 0.29 and 27.46 ± 0.21 mg/L, respectively), catechin (135.16 ± 6.47 mg/L) and epicatechin (51.33 ± 2.33 mg/L), the natural products known to exert significant lipid-lowering effects. Taken all together, the clone No. 010 developed in Serbia may offer new Cabernet Franc wine with geographical indication.