Thin layer chromatography efficiency,measurement

The sorption efficiency of MC was determined as the ratio of the quantity of the adsorbed substance to its initial amount (w / w), expressed in % for a certain ratio (w / w) of adsorbent to substance. Optimal ratios of adsorbent to substance equal 15-20 for barbiturates, 20 - 25 for cyanocobalamin and bilirubin, and 40 - 50 for hemoglobin. The initial concentration of absorbed substances was 100 - 200 pg/ml. The substances were incubated for lmin with MC either in physiological solution or in donor plasma and donor blood at room temperature (pH 7.4). The concentration of substances in the solutions was measured by differential visual and UV-spectroscopy. Concentrations of substances in blood and plasma and adsorption of total plasma proteins was determined by thin-layer chromatography with a fluorescent label. 

The low efficiency and short migration distances typical of thin-layer chromatography limit useful separations to those with relatively large enantioselectivity factors. Absorption by the chiral selector can cause baseline instability and reduced sample detectability for quantitative measurements by scanning densitometry. The chiral sepa-... 

Sample application is perhaps the most critical aspect of thin-layer chromatography, particularly for quantitative measurements. Usually, the sample, as a 0.01% lo 0.1 % solui ion, is applied as a spot I to 2 cm from the edge of the plate. Tor best separation efficiency, the spot should have a minimal diameter — about. 5 mm for qualitative work and smaller for quantitative analysis. For dilute solutions, three or four repetitive applications are used, with drying between. 

The lipophilicity, log Ptlc of membrane components as determined by thin-layer chromatography is of the utmost relevance to the lifetime of liquid-membrane sensors. Since blood serum and whole blood are much more lipophilic than a purely aqueous solution they are much more efficient extractants for membrane components. The lifetime decreases by a factor of 10 for direct measurements. Hence, much higher lipophilicities of host molecules and additives are required when membranes have to be contacted with these media. The required lipophilicity, logPxLCj of neutral carriers incorporated in ion-selective liquid membranes with a thickness of... 

Gas-flow counting is a method for detecting and quantitating radioisotopes on paper chromatography strips and thin-layer plates. Emissions are measured by interaction with an electrified wire in an inert gas atmosphere. AH isotopes are detectable however, tritium is detected at very low (- 1%) efficiency. 

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