Search results for "Enone"
showing 10 items of 320 documents
Exposure to Androstenes Influences Processing of Emotional Words
2018
This article is part of the Research Topic 'The Importance of Olfaction in Intra- and Interspecific Communication'; International audience; There is evidence that human-produced androstenes affect attitudinal, emotional, and physiological states in a context-dependent manner, suggesting that they could be involved in modulating social interactions. For instance, androstadienone appears to increase attention specifically to emotional information. Most of the previous work focused on one or two androstenes. Here, we tested whether androstenes affect linguistic processing, using three different androstene compounds. Participants (90 women and 77 men) performed a lexical decision task after bei…
Detection of banned drugs in sport by micellar liquid chromatography
1992
Abstract A rapid method for the determination of banned drugs in sport (including stimulants, anabolic steroids and diuretics) based on micellar liquid chromatography is proposed. The mobile phase is an aqueous solution of a surfactant (sodium dodecyl sulphate in this instance) and the stationary phase is octadecylsilica. The retention parameters of the drugs were established and the effect of a mobile phase organic modifier on the chromatographic behaviour of the compounds was studied. Improvements in efficiency were achieved by control of the temperature of the mobile phase. This method allows the direct injection of urine samples for the determination of drugs excreted free in urine: ami…
High-performance liquid chromatographic determination of spironolactone and its major metabolite canrenone in urine using ultraviolet detection and c…
1994
A rapid and simple column liquid chromatographic method involving a column-switching system for the determination of spironolactone and its main metabolite canrenone in urine is described. Purification and concentration was performed using an Hypersil ODS-C18, 30 microns (20 x 2.1 mm I.D.) pre-column. The most polar urinary compounds were removed by washing the pre-column with water, and the analytes were subsequently switched to a LiChrospher RP C18, 5 microns (125 x 4 mm I.D.) analytical column and separated by means of an acetonitrile-water mobile-phase. Under the proposed conditions, the extraction efficiency was approximately 100% over the 0.5-10.0 micrograms/ml concentration range. Th…
Development of a fully automated sequential injection solid-phase extraction procedure coupled to liquid chromatography to determine free 2-hydroxy-4…
2010
Abstract 2-Hydroxy-4-methoxybenzophenone and 2-hydroxy-4-methoxybenzophenone-5-sulphonic acid, commonly known as benzophenone-3 (BZ3) and benzophenone-4 (BZ4), respectively, are substances widely used as UV filters in cosmetic products in order to absorb UV radiation and protect human skin from direct exposure to the deleterious wavelengths of sunlight. As with other UV filters, there is evidence of their percutaneous absorption. This work describes an analytical method developed to determine trace levels of free BZ3 and BZ4 in human urine. The methodology is based on a solid-phase extraction (SPE) procedure for clean-up and pre-concentration, followed by the monitoring of the UV filters by…
Sequential injection analysis for benzophenone-4 and phenylbenzimidazole sulphonic acid in sunscreen sprays by solid-phase extraction coupled with ul…
2002
Abstract A sequential injection UV method was developed to determine benzophenone-4 (BZ4) and phenylbenzimidazole sulphonic acid (PBS) simultaneously, these being the most commonly used UV-filters in aqueous formulations used as sunscreen sprays. The selective elution of both was performed by on-line solid-phase extraction, by retention on a SAX microcolumn and separation by varying the pH of elution. The sensitivity obtained was 0.042±0.001 ml μg −1 for PBS and 0.0159±0.0003 ml μg −1 for BZ4. The limit of detection was 1.6 μg ml −1 for PBS and 0.6 μg ml −1 for BZ4. The R.S.D. of the results was 1–6% for PBS and 1–12% for BZ4. The method was validated using commercial sunscreen formulations…
Sensitive determination of free benzophenone-3 in human urine samples based on an ionic liquid as extractant phase in single-drop microextraction pri…
2007
Abstract Benzophenone-3 (BZ3), one of the compounds most commonly used as UV filter in cosmetic products, can be absorbed through the skin into the human body, since it can be found at trace levels in urine from users of cosmetic products that contain BZ3. Moreover, different undesirable effects have been attributed to this compound. Thus, sensitive analytical methods to monitor urinary excretion of this compound should be developed. This paper presents a selective and sensitive methodology for BZ3 determination at ultratrace levels in human urine samples. The methodology is based on a novel microextraction technique, known as single-drop microextraction (SDME). An ionic liquid (IL) has bee…
Sequential injection spectrophotometric determination of oxybenzone in lipsticks
2001
A sequential injection (SI) procedure for the spectrophotometric determination of oxybenzone in lipsticks is reported. The colorimetric reaction between nickel and oxybenzone was used. SI parameters such as sample solution volume, reagent solution volume, propulsion flow rate and reaction coil length were studied. The limit of detection was 3 microg ml(-1). The sensitivity was 0.0108+/-0.0002 ml microg(-1). The relative standard deviations of the results were between 6 and 12%. The real concentrations of samples and the values obtained by HPLC were comparable. Microwave sample pre-treatment allowed the extraction of oxybenzone with ethanol, thus avoiding the use of toxic organic solvents. E…
Determination of hydroxylated benzophenone UV filters in sea water samples by dispersive liquid-liquid microextraction followed by gas chromatography…
2010
A new analytical method for the determination of four hydroxylated benzophenone UV filters (i.e. 2-hydroxy-4-methoxybenzophenone (HMB), 2,4-dihydroxybenzophenone (DHB), 2,2'-dihydroxy-4-methoxybenzophenone (DHMB) and 2,3,4-trihydroxybenzophenone (THB)) in sea water samples is presented. The method is based on dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS) determination. The variables involved in the DLLME process were studied. Under optimized conditions, 1000 microL of acetone (disperser solvent) containing 60 microL of chloroform (extraction solvent) were injected into 5 mL of aqueous sample adjusted to pH 4 and containing 10% NaCl…
A rapid HPLC assay for zearalenone in laboratory cultures ofFusarium graminearum
1993
A high pressure liquid chromatographic (HPLC) method to determine zearalenone in corn contaminated withFusarium graminearum is described. After extraction with methanol-water and solvent partition, samples were cleaned up by applying the extract to a disposable silica cartridge and by eluting the toxin with a mixture of hexane/dry ethyl ether (5/5). Separation was achieved by a reverse phase μBondapak C18 column followed by fluorescence detection using an excitation wavelength at 274 nm and an emission wavelength at 440 nm. Detection limit was about 5 ng. Recoveries ranging from 85.37 to 100.97%, in standard solutions range 30–0.5 µg/ml, were found.
Diastereoselective synthesis of spongian diterpenes. Total synthesis of the furanoditerpene (−)-spongia-13(16),14-diene
1999
Abstract An effective diastereoselective synthesis of the marine-sponge metabolite (−)-spongia-13(16),14-diene 1 is achieved starting from S-(+)-carvone via a homochiral phenanthrenone as the key intermediate for the construction of the furan ring system. S-(+)-Carvone was transformed into the phenanthrenone 2a in six steps (53% overall yield), using an intramolecular Diels-Alder reaction as the key step. Conversion of the enone function in 2a into an epoxyaldehyde function followed by cyclisation and aromatisation in acid conditions completed the construction of ring D.