The identification and determination of transformation products (TPs) of pharmaceuticals is essential nowadays, in order to track their fate in the aqueous environment and, thus, to estimate the actual pollution. However, this is a challenging task due to the necessity to apply high-resolution instruments enable to detect known and unknown compounds. This work presents the use of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) as a powerful tool for the identification of three selected pharmaceuticals, furosemide (FUR), ibuprofen (IBP), and ketoprofen (KET), and their TPs in various water samples. Laboratory degradation experiments were performed using xenon lamp as a source of the irradiation in order to simulate phototransformation processes which may occur in the environment. Furthermore, the photodegradation kinetics of three selected compounds were assessed in a reactor equipped with xenon lamp in river water samples. Five TPs of IBP, seven of KET, and five of FUR were identified; some of them are presented here for the first time. Accurate mass measurements and fragmentation pattern obtained during an LC-QTOF-MS analysis allowed for structure elucidation of TPs followed by the creation of transformation pathway of selected pharmaceuticals. Finally, different water samples (wastewater influent and effluent, river water, untreated and treated water) were analyzed in order to estimate the presence of parent and transformed compounds. Only KET was detected in untransformed form in considered samples. Most of the TPs of selected drugs were found at least once in all water samples. Although IBP and FUR were not present in water samples as parent compounds, their different TPs occur. A great potential of LC-QTOF-MS in the identification and structural elucidation of TPs in the environment, allowing the recognition of the fate of pharmaceuticals in the environment through the determination of transformation pathway, has been presented. Phototransformation of three selected pharmaceuticals

A systematic approach to the characterization of selenized yeast supplements in terms of the speciation of selenium was developed. The optimized fractionation procedures included the sequential leaching of water soluble, cell-wall bound, and membrane-protein selenium followed by a further fractionation of each extract by high-resolution size-exclusion chromatography. The stability of fractions collected as chromatographic peaks was investigated in the presence of a proteolytic enzyme (pronase XIV) and trypsin in order to discriminate between selenium-containing peptides and other selenocompounds. Reversed-phase HPLC of tryptic digests of size-exclusion chromatographic fractions allowed the identification of selenopeptides by MALDI and electrospray MS. The complexity of the speciation of the water-soluble selenium in yeast was confirmed. Surprisingly, selenomethionine in the water insoluble fraction was found to be bound physically to cell wall constituents rather than being incorporated chemically into the protein structure, in contrast to former studies.

Starting from the sampling up to the time of analysis, the content of water sample can be altered due to the chemical, physical, and biological reactions it undergoes. This article deals with the processes occurring in the water samples during their storage and with reasons of their occurrence. Special attention has been paid to the chemical and physicochemical reactions as well as to microbiological and photochemical degradation of the component of the sample. Techniques for the water sample preservation are also reviewed.