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Öğe Determination of cadmium and lead in urine by flame atomic absorption spectrometry after activated carbon enrichment(Polskie Towarzystwo Chemiczne-Polish Chemical Soc, 1996) Aydemir, T; Gucer, SIn this study, ammonium pyrrolidine dithiocarbamate was used as a complexing agent in the enrichment step for the determination of cadmium and lead in urine. The recoveries were above 90 % and the factors effecting recoveries, such as sample preparation, pH, amount of activated carbon, complexing reagent and the contact time,were studied. The interference effects from matrix components were compared after activated carbon enrichment. The calibration graphs were rectilinear for a range 1.2-80 mu g l(-1) and 1.6-53 mu g l(-1) for cadmium and lead, respectively. The relative standard deviations of the measurements (n=9) at concentration of 20 mu g l(-1) were 3 % for cadmium and lead. Detection limits,defined as 3 s of blanks were 1.2 mu g l(-1) for cadmium and 1.6 mu g l(-1) for lead. The untreated urine (300 ml) was adjusted to pH 6 and 4 ml of 2% APDC solution were added to complex the metals. The mixture was stirred with 500 mg activated carbon for 40 min and next was filtered. The metals were leached with nitric acid.Öğe Determination of nickel in urine by flame atomic absorption spectrometry after activated carbon enrichment(Taylor & Francis Inc, 1996) Aydemir, T; Gucer, SAn enrichment method is described for the determination of nickel in urine by flame atomic absorption spectrometry after preconcentration with ammonium pyrrolidine dithiocarbamate on activated carbon. The recoveries are above 90 %. The factors affecting recoveries, such as pH, amounts of activated carbon and complexing reagent, and the contact times, were also studied. The calibration graph was rectilinear for the range 2.4-80 mu g l(-1). The relative standard deviation of the measurement was 3 % for nickel at a concentration of 20 mu gl(-1) (n=9). The detection limit of the method was 0.75 mu g l(-1) when 500 ml urine was used.Öğe Voltammetric determination of timolol maleate(Maik Nauka/Interperiodica, 2001) Türkdemir, MH; Erdögdu, G; Aydemir, T; Karagözler, AA; Karagözler, AETimolol as a beta -adrenoceptor antagonist is a potent antihypertensive and antianginal drug, which was also proved to be effective for the secondary prevention of myocardial infarction. The analysis of timolol, as with other oxprenolols, in ophthalmic solutions and biological liquids using sensitive instrumental methods has gained importance. Investigation of the electrochemical behavior of timolol maleate on a mercury drop electrode reveals the presence of a specific reduction peak of analytical significance. Analysis conditions affecting the properties of this peak were optimized by a systematic study. The limit of detection of about 2.5 ppb, obtained for the DPV technique using SMDE, is comparable with the most sensitive techniques. This method is suitable for routine analysis in that it is simpler and requires no preconcentration step for the analysis of therapeutic doses of the drug.
