Although there is increasing concern about residues from personal care products entering the aquatic environment and their potential to accumulate to levels that pose a health threat to humans and wildlife, we still know little about the extent and magnitude of their presence in the aquatic environment. In this study we describe a procedure for isolation, and subsequent determination, of compounds commonly added to personal care products. The compounds of interest include UV filters with the commercial name Eusolex (homosalate, 4-methylbenzylidenecamphor, benzophenone-3, octocrylene, butylmethoxydibenzoylmethane, ethylhexyl methoxycinnamate) and two common anti-microbial agents, clorophene and triclosan. Water samples were filtered, acidified, and extracted by use of solid-phase extraction. Extracted compounds were then derivatised before analysis by gas chromatography-mass spectroscopy. By use of our method we obtained limits of detection of 13-266 ng L(-1) for UV filters, and 10-186 ng L(-1) for triclosan and clorophene. Recoveries were 82-98% for deionised water and 50-98% for natural water (seawater, pool water, lake water, and river water). Samples collected in Slovenia included seventeen recreational waters (seawater, pool water, lake water, and river water; August 2004) and four wastewaters (January 2005). The most abundant UV filter was benzophenone-3 (11-400 ng L(-1)). Of the two anti-microbial agents studied, trace amounts, only, of triclosan were present in the river Kolpa (68 ng L(-1)) and in an hospital effluent (122 ng L(-1)).
The aim of this work was to study selenium (Se) speciation in the potato ( Solanum tuberosum L.) cultivar Desiree, enriched in Se by foliar spraying with a water solution containing 10 mg of Se/L in the form of sodium selenate. Four combinations of treatments were used: well-watered plants with and without Se foliar spraying and drought-exposed plants with and without Se foliar spraying. Water-soluble Se compounds were extracted from potato tubers by water or enzymatic hydrolysis with the enzyme protease XIV, amylase, or a combination of protease XIV and amylase. Extraction was performed using incubation at a constant temperature and stirring (37 degrees C at 200 rpm) or by ultrasound-assisted extraction (300 W), using different extraction times. Separation of soluble Se species (SeCys2, SeMet, SeMeSeCys, selenite, and selenate) was achieved by ion-exchange chromatography, and detection was performed by inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that the concentration of selenate extracted was independent of the enzymatic extraction technique (approximately 98 ng/g for drought-exposed and 308 ng/g for well-watered potato tubers), whereas the extraction yield of SeMet changed with the protocol used (10-36%). Selenate and SeMet were the main soluble Se species (representing 51-68% of total Se) in potato tubers, regardless of the growth conditions.
Since there is growing awareness of the strong dependence of the antioxidative function of selenium (Se) upon its chemical form, the stability of Se species during sample preparation is an important factor in obtaining qualitative and quantitative results. Many plant samples are rich in phenolic compounds (antioxidants), but data about their effect on specific Se species in extracts of plant samples are scarce. Therefore, the aim of this study was to investigate the effect of the most common phenolic substances in plant parts, namely tannin and the flavonoid rutin, on the concentration and/or transformation of several Se species (SeMet, SeCys(2), SeMeSeCys, Se(VI) and Se(IV)) during sample preparation (24 h incubation at 37 degrees C) and storage (4 days at 4 degrees C). Moreover, the effect observed was then studied in a real sample, buckwheat, because this plant is known as a rich source of phenolics, especially tannin and rutin. Se speciation was carried out by on-line coupling of ion-exchange HPLC-ICP-MS after water and enzymatic (protease) hydrolysis. The results showed that the ratio between the two antioxidants has an important role. When the antioxidants were present together, the response for Se(IV) was observed to start to decrease only at a ratio of rutin to tannin of 1:100 (w/w), indicating the ratio between antioxidants in buckwheat seeds. After water extraction, only 40% and after enzymatic extraction 80% of Se(IV) remained, but no other Se compound was detected with the system used. Furthermore, the extracts were not stable during storage at 4 degrees C. Signals for other Se species were stable. The results obtained for buckwheat seeds showed a decrease in Se(IV) response during sample preparation and storage, comparable to the one obtained with the experiments performed in vitro. However, Se species in extracts of other buckwheat parts (leaves, stems and sprouts) were stable. These results indicate that reactions in the extraction process and during storage may affect Se speciation and may result in misidentifications and inaccurate values.
The aim of this work was to check whether commercially available enzymes are pure enough to be used for selenium speciation analysis and the contribution that impurities could make to Se determination in real samples. For this purpose, twelve commercially available enzymes with different origins and classifications (protease, amylase, cellulase, lipase) were analysed. After the dissolution of the enzyme in water, the Se species were separated by ion exchange chromatography, with inductively coupled plasma mass spectrometry used as the detection system. The results showed that the Se content was significant in several cases. The highest value was obtained for beta-amylase from barley, 3100 ng Se per g of enzyme. Speciation analysis showed that Se-methionine, selenite, selenate and some unknown compounds were present in several enzymes. In general, the Se species identified represented a small fraction of the total Se. For instance, only 17% of the total Se was determined for beta-amylase from barley. On the other hand, about 100% of the total Se was identified in protease from Streptomyces griseus. Upon comparing the results from different lots of the same enzyme, not all of them were found to be comparable. Thus, the presence of selenium species in commercially available enzymes could be due to the preparation procedure used for the enzyme; they could be present as degradation products. Therefore, when determining selenium species in samples with low Se contents, attention should be paid to enzyme purity in relation to selenium compounds when an enzyme is used for hydrolysis.
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