Optimized HPLC method for tramadol and O-desmethyl tramadol determination in human plasma.

The optimized method for HPLC determination of tramadol and its metabolite O-desmethyl tramadol in human plasma using sotalol as internal standard has been developed and validated by a new approach. The determination by fluorescence detection was performed on re-eluted solution, obtained after liquid-liquid extraction with ethyl acetate of the three analytes from plasma. The chromatographic separation of tramadol under a gradient elution was achieved at a temperature of 15 degrees C with a RP-18 column, guarded by a C18 precolumn. The mobile phase was a mixed aqueous solution containing ortho-phosphoric acid, triethylamine, acetonitrile and methanol in a complex gradient mode. The quantitative determination of tramadol was performed at different successive pairs of excitation/emission wavelengths (200/300 nm, 200/295 nm, 212/305 nm) with lower limits of quantification: LLOQ=4.078 ng/ml for tramadol, respectively LLOQ=3.271 ng/ml for O-desmethyl tramadol. For the LLOQ limits, were calculated the values of the coefficient of variation and difference between mean and the nominal concentration. For tramadol analyte they were CV%=5.147% and bias%=-7.273% in the intra-days and CV%=4.894% and bias%=0.836% in the between-days assay, respectively for the metabolite O-desmethyl tramadol they were CV%=11.517% and bias%=0.337% in the intra-days and CV%=6.41% and bias%=3.259% in the between-days assay. In addition, the stabilities of the analytes were verified in different conditions. Both, tramadol and its metabolite proved to be stable in plasma for four weeks, frozen at -20 degrees C, but also for 48 h at 15 degrees C in the re-eluted solution after liquid-liquid extraction.

[Detection of the sensitivity of some bacteria and fungi to the action of sodium phosphotungstate beta-Na6[P2W18O62].18 H2O]. / Determinarea sensibilitatii unor bacterii si ciuperci la actiunea fosfowolframatului de sodiu beta-Na6[P2W18O62].18 H2O.

Poliyoxometalales are a very special category of the chemical compounds that have multiply properties and possibility to application in a lot of actual domain of the scientific research. One of the most practice application of the polyoxometalates with a special significance is their antibacterial and anti fungus actions. For this study, there have been used fungus, Gram-positive and Gram-negative bacteria, and the action of the polyoxometalates was tested simultaneously with the action of the specifically antibiotics for the studied bacteria. In order to determine the fungus and bacteria sensibility to the tested substance, there have been used three methods: two qualitative, diffusion methods (rondel and bucket methods) and one quantitative method (determination of the minimum inhibitory concentration-MIC). The results of the bucket method were similarly with ones obtained with the rondel method: only Staphylococcus aureus strains were sensitive to the sodium phosphotungstate. Using the quantitative method (MIC) have been emphasized that Pseudomonas aeruginosa and Klebsiella pneumoniae strains were sensitive in time to the studied substance.

The enzymatic activity from the sediment of the Gilau dam reservoir - Cluj county.

The enzymological studies on the sediment of the accumulation lake that has the main purpose of supplying drinking water to the city of Cluj-Napoca and the nearby villages, were aimed at the comprehensive understanding of the complex processes that happen in these habitats of special significance. In the sediment samples the following enzymatic activities have been quantitatively determined: phosphatase, actual and potential dehydrogenase, catalase, urease and protease. Non-enzymatic catalytic activity was also measured. Based on the relative values for the enzymatic activities, the enzymatic indicator of the sediment quality (EISQ) was calculated (ranging from 0.1 to 0.7). The enzymatic activities have been qualitatively determined for maltase, saccharase, lactase, cellobiase, amylase, dextranase, levanase, cellulase and inulinase. The correlation between the enzymatic and bacteriologic potential was statistically calculated.