Cimaterol and clenbuterol residue analysis by HPLC-HPTLC in liver.

A method has been developed for the analysis of cimaterol and clenbuterol residues in liver, with detection limits of 0.25 micrograms/kg and 0.5 micrograms/kg, respectively. The recovery varied from 55% to 60%. After extraction, a clean-up procedure with Baker-spe C-18 columns was performed. The two chemical compounds of interest were eluted with methanol. Cimaterol and clenbuterol were quantitatively determined by high-performance liquid chromatography (HPLC) using an RP-Select B (5 microns) column and a post-column reaction procedure. The positive results were confirmed by high-performance thin-layer chromatography (HPTLC) as this technique reaches the same level of sensitivity as the HPLC method.     

A formal framework for scenario development in support of environmental decision-making

Scenarios are possible future states of the world that represent alternative plausible conditions under different assumptions. Often, scenarios are developed in a context relevant to stakeholders involved in their applications since the evaluation of scenario outcomes and implications can enhance decision-making activities. This paper reviews the state-of-the-art of scenario development and proposes a formal approach to scenario development in environmental decision-making. The discussion of current issues in scenario studies includes advantages and obstacles in utilizing a formal scenario development framework, and the different forms of uncertainty inherent in scenario development, as well as how they should be treated. An appendix for common scenario terminology has been attached for clarity. Major recommendations for future research in this area include proper consideration of uncertainty in scenario studies in particular in relation to stakeholder relevant information, construction of scenarios that are more diverse in nature, and sharing of information and resources among the scenario development research community.     

Clenbuterol residue analysis by HPLC-HPTLC in urine and animal tissues

A method for clenbuterol residue analysis in urine and animal tissues has been developed. The detection limits are 0.25 micrograms/l and 0.5 micrograms/kg, respectively. The recovery in urine varies from 85% to 90% and in animal tissues from 70% to 74%. The beta 2-agonist was liberated from the tissues by an enzymatic digestion, purified on Chem Elut columns using alkaline conditions and extracted with 0.01 mol/l HCl. Clenbuterol was quantified by high-performance liquid chromatography (HPLC) on a RP-8 column and a post-column reaction procedure. High-performance thin-layer chromatography (HPTLC) was performed on silica gel 60 plates and clenbuterol visualized by means of the modified Ehrlich's TLC spray reagent. Since this method is sensitive, as is HPLC, it was used to obtain a confirmation and to exclude false positive results.     

Changes in the perceived duration of a narrowband sound induced by a preceding stimulus.

The authors show that a narrowband noise (NBN) is perceived as longer when presented immediately after a wideband noise (WBN), compared to when the WBN is absent. This effect depended on the WBN’s frequency spectrum overlapping that of the NBN, and it increased as the duration of the WBN increased up to 300 ms. It decreased when a silent gap was introduced between the WBN and NBN, but remained significant for an easily detectable gap of 40 ms. A correlate of the effect was observed in the mismatch negativity (MMN) to a deviant stimulus, consisting of a WBN + NBN, presented in a sequence of more common isolated WBNs. The MMN latency was longer for an on-frequency than for an off-frequency WBN; and, more importantly, the size of this difference correlated across participants with the difference in perceived duration. A rhythm-adjustment experiment showed that the presence of an on-frequency WBN immediately preceding a tone caused that tone to be heard as starting earlier than when the WBN was absent. The results are discussed in relation to the continuity illusion and models of duration encoding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hydrophilic interaction liquid chromatography coupled to electrospray mass spectrometry of small polar compounds in food analysis

Reversed-phase liquid chromatography (RPLC) is commonly used to analyze nonvolatile components in food. However, polar low-molecular-weight compounds such as hydrophilic amino acids, di- and tripeptides, and organic acids are often not sufficiently retained and represent a challenge for RPLC. Hydrophilic interaction liquid chromatography in combination with electrospray mass spectrometry (HILIC-ESI-MS) on a carbamoyl-derivatized stationary phase was successfully employed to separate free amino acids and small polar peptides in complex food matrixes such as wheat gluten hydrolysate and Parmesan cheese. Glutamyl dipeptides were separated in a sequence-specific order with peptides with N-terminal glutamic acid residues eluting prior to their reverse sequence analogues. ESI-MSn detection in the positive ionization mode provided the necessary information to unambiguously identify isobaric peptides due to their characteristic fragmentation patterns. The technique also proved useful to separate and identify glycoconjugates between amino acids and reducing sugars (Amadori compounds). The investigation of organic acids present in food used a mobile phase comprising ammonium acetate buffer at pH 7 and mass spectrometric detection in the negative ionization mode.     

Aluminum nitride by microwave-assisted synthesis: Effect of added ammonium chloride

Hexagonal aluminum nitride (AlN) crystals were synthesized by microwave method with ammonium chloride used as an additive. Starting mixtures consisted of Al powder, NH₄Cl, and urea as a fuel taken in a 1: 3: 1 ratio. The microwave oven operated at 630 W, the synthesis time was 10, 30, 60, and 120 min. The results showed that the pure AlN powder with regular and fine grains could be obtained in 30 min. The synthesized powders were characterized by TGA/DTA, XRD, FT-IR, UV-VIS, SEM, and TEM.     

Diminished cooperativeness of psychopaths in a prisoner's dilemma game yields higher rewards.

Maladaptive social behavior is one of the defining characteristics of psychopathic personality disorder. Nevertheless, maladaptive social behavior has only rarely been observed among psychopaths in experimentally controlled situations. The authors assessed the behavior of criminal psychopaths from high-security psychiatric hospitals in a computer simulation of a social dilemma situation. The psychopaths showed a markedly higher proneness to competitive (i.e., noncooperative) behavior than did healthy adults from the general population. The odds ratio between defection and being a psychopath was estimated at 7.86 in the sample. The probability to choose selfish instead of cooperative behavior was significantly linked to the following subscales of the Psychopathy Personality Inventory-Revised (S. O. Lilienfeld & M. R. Widows, 2005): rebellious nonconformity, Machiavellian egocentricity, and the total score. On average, the psychopathic participants accumulated higher gain and more strongly exploited their counterpart than did the healthy participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Salbutamol identification in liver and urine by high-performance thin-layer chromatography and densitometry.

This paper describes a rapid method for the identification of salbutamol in liver and urine. Salbutamol is extracted from liver with an acid solution, purified on Baker columns and eluted with methanol. After derivatization, salbutamol is detected on HPTLC plates as a blue spot. Urine samples are directly purified on the C18 columns and then the same procedure is followed as for the liver samples. Using this screening method, salbutamol can be semi-quantitatively determined at the micrograms/kg level.     

A two-dimensional high-performance thin-layer chromatographic screening method for sulphonamides in animal tissues

Summary A procedure for the identification of sulphonamides in edible animal tissues by two-dimensional high-performance thin-layer chromatography is described. Sixteen sulphonamides can be detected at an absolute level of 10 ng. The absolute detection limit of the sulphonamide standards is 1 ng. After extraction of the sulphonamides with chloroform/acetone, the acidified extract is concentrated and purified using a cation-exchange solid phase extraction column. The column is treated with ammonia vapour and the sulphonamides are then eluted with methanol. Blank samples of edible animal tissues spiked with sulphonamides (frequently used in Belgium) result in very good separation.

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Identifizierung von sulfonamiden in geweben von schlachttieren mittels zweidimensionaler hochleistungsdünnschichtchromatographie

Zusammenfassung Eine Methode zur Identifizierung von Sulfonamiden in Geweben von Schlachttieren mittels zweidimensionaler Hochleistungsdünnschichtchromatographie wird beschrieben. 16 Sulfonamide können identifiziert werden, wobei die absolute Empfindlichkeitsgrenze bei 10 ng liegt. Die absolute Nachweisgrenze für die Referenzsubstanzen liegt bei 1 ng. Nach Extraktion der Sulfonamide mit Chloroform-Aceton wird die angesäuerte Extraktlösung auf einer Kationenaustausch-Extraktionssäule eingeengt und gereinigt. Die Säule wird mit Ammoniakdämpfen behandelt und die Sulfonamide werden anschliessend mit Methanol eluiert. Die den Gewebeextrakten zugefügten in Belgien häufig verwendeten Sulfonamide konnten sehr gut voneinander getrennt werden.

     

Determination of residual isopropanol and propylene glycol in soft drinks by glass capillary gas chromatography

European Food Research and Technology - A method is described for the quantitative determination of the residual solvents isopropanol and propylene glycol in soft drinks. The proposed methods are...