Novel PFAS-specific monitoring approach for highly impacted surface waters.

In regulatory environmental monitoring programs, only a very small fraction of the vast number of per- and polyfluoroalkyl substances (PFAS) are investigated by target analysis. Therefore, non-target analysis (NTA) studies are increasingly conducted to detect unknown or unnoticed PFAS. These studies are often based on a few grab samples. Thus, discontinuously emitted PFAS from industrial batch processes might be easily overlooked. To address this deficiency and obtain in-depth information on the occurrence and temporal trend of PFAS in surface water impacted by treated industrial waste water, a comprehensive target and NTA study was implemented for 29 months. Elevated PFAS concentrations with up to 10.8 µg L-1 were detected in the river water by target analysis. In addition to PFAS target analysis, the water samples were analyzed by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS). Data processing strategies and various filtering steps were applied to prioritize PFAS. Substances were identified by comparing data to available internal and external PFAS suspect lists, a fragment ion and neutral loss list, and spectral libraries. Several compounds were unequivocally identified based on reference standards. Fifty-five PFAS were (tentatively) identified using NTA. Of those, 43 could be assigned to 13 different homologous series. Partly fluorinated short-chain carboxylic acids (H-PFCA) and sulfonic acids (H-PFSA) were predominantly found in addition to perfluoroalkyl carboxylic acids (PFCA) and the alkyl ether carboxylic acid DONA. To the best of our knowledge, 12 PFAS were reported in surface water for the first time. Signal intensities of individual PFAS and signal ratios varied widely over time, which may indicate batch operations leading to discontinuous emission. Results and insights from this screening approach on PFAS can be used to optimize forthcoming surface water monitoring programs by including newly identified PFAS and selecting appropriate sampling intervals.

Selective trace analysis of diclofenac in surface and wastewater samples using solid-phase extraction with a new molecularly imprinted polymer.

A new molecularly imprinted polymer (MIP) for trace analysis of diclofenac in environmental water samples was prepared by a non-covalent protocol in which diclofenac was used as a template molecule. Diclofenac is a member of the class of drugs termed non-steroidal anti-inflammatory drugs (NSAIDs) which belong to the most frequently detected pharmaceuticals in the water-cycle in Europe. The MIP was synthesized using 2-vinylpyridine (2-VP) and ethylene glycol dimethacrylate (EGDMA) as a functional monomer and cross-linker, respectively, and bulk thermal polymerization method. (1)H NMR spectroscopy was used to study the interaction between diclofenac and 2-VP mixed in toluene-d(8) in pre-polymerization complex. Two non-covalent bonds were formed i.e. ionic interaction and hydrogen bonding. The binding characteristics of the MIP and diclofenac were evaluated using equilibrium binding experiments. Scatchard plot analysis revealed that two classes of binding sites were formed with dissociation constants of 55.6 micromol L(-1) and 1.43 mmol L(-1), respectively. Various parameters affecting the extraction efficiency of the polymers have been evaluated to achieve the selective preconcentration of diclofenac from aqueous samples and to reduce non-specific interactions. This resulted in an MISPE-LC/DAD method allowing the direct extraction of the analyte from sample matrix with a selective wash using dichloromethane/acetonitrile (94:6, v/v) followed by elution with dichloromethane/methanol (85:15, v/v). The recovery of a 100 ng diclofenac standard spiked into 200 mL of blank surface water was 96%, with good precision (RSD=3.3%, n=3). The MISPE was demonstrated to be applicable to the analysis of diclofenac in raw influent and final effluent wastewater samples from sewage treatment plant and revealed diclofenac concentrations of 1.31+/-0.055 microg L(-1) (n=3) and 1.60+/-0.049 microg L(-1) (n=3), respectively. Yielded results were in good agreement with the corresponding LC/TIS/MS/MS data obtained by an independent laboratory which were 1.40 and 1.50 microg L(-1) for influent and effluent samples.

Formation of acids, lactones and esters through the Maillard reaction.

From a glucose/glycine reaction mixture acids, esters and lactones were isolated and identified. Sugar degradation products could also be determined as benzimidazole derivatives after reaction with o-phenylenediamine. Results derived from model systems suggested possible reaction pathways leading to some of the isolated substances. A lactic acid ester is formed as a product of an unstable beta-pyranone intermediate. A 3-deoxyhexosone serves as a precursor of two furanolactones.

[Maillard reaction of bovine serum albumin with glucose. Determination of 2-formyl-5-(hydroxymethyl)pyrrole-1-norleucine by high-performance liquid chromatography after alkaline hydrolysis]. / Maillard-Reaktion von Rinderserumalbumin mit Glucose hochleistung-flüssigkeitschromatographischer Nachweis des 2-Formyl-5-(hydroxymethyl)pyrrol-1-norleucins nach alkalischer Hydrolyse.

Reactions between glucose and bovine serum albumin proceed predominantly at the side chain amino groups of lysine residues. Among other products, protein-bound 2-formyl-5-(hydroxymethyl)pyrrole-1-norleucine is formed. After alkaline hydrolysis and fractionation of the protein hydrolysate on RP-18 material this substance can be separated by high-performance liquid chromatography. The identity of the norleucine derivative with a synthesized compound can be determined with fast atom bombardment-mass spectrometry spectral data. A colour reaction with thiobarbituric acid is also suitable for detection.

Chemical pathways of the Maillard reaction.

From reaction mixtures of reducing sugars with primary and secondary amines many heterocyclic and carbocyclic compounds have been separated. From the structures of these substances together with the knowledge about reactive intermediates some degradation pathways can be proposed. Caused by the nature of the sugar (pentose, mono- or disaccharide) and the amine (primary or secondary) differences in the pathways are observed. An attempt is made to present some reactions with emphasis to the Maillard reaction in mammalians.