Optical density values

I, the extremely low concentration of polymer in the fractions collected reduced the precision in the ultraviolet optical density values measured, the influence of which is amplified in the figures in the last column. Therefore, the average styrene content was used as the composition of the peak point to calculate the MW of the polymer by Equation 5. The MW of the styrene homopolymer which is present in small amounts was taken as the MW of the first block, as explained above. In this manner the molecular structure of the polymer was found to be S( 15,000) B(61,000)S( 14,000) the figures given in parentheses being the MW s of the successive blocks. 

The concentration of antibody-toxin conjugate in samples is determined from the optical density values at 492 nm, given by a standard curve. The standard curve is obtained by the same procedure using dilutions of the stock antibody-toxin solution having final concentrations between 0.125 and 20 ng/mL in casein buffer. 

Initially, particle optical density values increased slowly, but in the vicinity where the additives get depleted (-10,000 km), particle density values increased... 

Read the optical density at 405 nm using a Microplate Autoreader. Calculate the mean optical density values of quadruplicate wells containing polynucleotide solution with the same spermidine concentration, for example, wells C4, D4, E4, and F4. 

In order to determine the efficacy of spermidine to provoke the B->Z transition, plot the net optical density values against the concentration of spermidine. The midpoint concentration isdetermined from this plot at 50% increase in net optical density. 

Add 20 pL of Amp-RT product per well. Include probe only wells as a control for nonspecific binding, and substrate-only wells to determine the optical density value of pure peroxidase substrate. Incubate for 30 min at 37°C. 

One can now write an equation relating the optical density value DTt to the number of flashes ... 

Enzyme standards, whose units are established carefully by a manual method using the incubation time of the AutoAnalyzer procedure, provide a direct means of translating AutoAnalyzer optical density values into enzyme units. This latter practice avoids the introduction of unique AutoAnalyzer units with different levels of normal and standard deviation, an event to be avoided if possible. 

When optical density of aluminum standards prepared by dissolving either aluminum wire in HC1 solution or aluminum sulfate in water is measured as a function of aluminum concentration using the modified procedure, curves of the type shown in Figure 1 are obtained. Optical density values plotted on this figure, which are for duplicate sets of experiments, were read about 30 minutes after having added the 2 ml of hydroxylamine hydrochloride. The straight line curve appears to obey Beers law at least up to 0.05-0.06 mg of aluminum. The pH of the standard solutions before analysis was in all cases below 3. 

Cytotoxicity test The L929 fibroblast cell line is the most widely used for cytotoxicity assessment 9-11. The cell metabolic activity was evaluated by succinc acid dehydrogenase (SDH) of mitochondria in living cell, which can deoxidized MTT salt into insoluble purple crystal. These crystals can be resolved by dimethyl sulfoxide (DMSO), and measured by the spectrophotometric microplate reader at 490 nm. To some extent, the optical density value (OD) of supernatant raised with the number of the living cell. Therefore, the measurement of MTT crystal OD can reflect the relative growth rate and the activity of cells, which can also leads to a reliable assessment to the cytotoxicity of the sample. 

Generally the sensitivity of photographic systems Is closely related to the so-called sensltometrlc curve giving the optical density value of a material as a function of the light exposure. 

This procedure takes place in two stages. Initially, 10 ml of wine with a normal pH is mixed with 2 ml of water. The optical density value (di) is measured at 520 nm on a 1 mm optical path. The same operation is carried out again, replacing the water with 2 ml of sodium bisulfite solution (d = 1.24), waiting 5 min and measuring optical density under the same conditions to obtain the value d2. ... 

White musts and wines contain benzoic and cinnamic acids, catechins, procyanidins and flavonols (Ribereau-Gayon, 1964 Weinges and Piretti, 1972). A recently discovered class of protein-tannin complexes has been shown to contribute towards the phenol content of white wine (Lea et al, 1979 Singleton et al, 1979). This is the reason for the excessively high result of the Folin-Ciocalteu test and the optical density value of 280 nm (Section 6.4.1)... 

Measure Cy3 absorbance at 552 nm and Cy5 absorbance at 650 nm. Then, use the appropriate molar extinction coefficient (e) to determine the molarity of each (e of Cy3 = 150,000 M cm e of Cy5 = 250,000 M cm ). To determine the amount of conjugated dye, the labeled samples are diluted 5 1 in Ab microarray desalting buffer. Optical density values for Cy3-labeled samples are read at 552 nm and for Cy5-labeled samples are read at 650 nm. Dye to protein ratios are determined using the following equations ... 

Usually 15-25 pL of sample will result in optical density values that in the middle of the standard curve. 

Results were expressed as percentage of binding, derived from the mean optical density values of five repetitions for each competitor concentration (percentage of binding = 100 x optical density of the test competitor concentration / optical density without competitor). 

The most absorption in all solutions takes place in short wave part of the effective wave band. More concentrated solutions (10 , 10 mole/1) of ascorbic acid have maximum absorption in the length interval of 220-280 nm, of paracetamol-220-310 nm, paracetamol with ascorbic acid-200-320 mn. Tendency to narrowing of absorption Cbld, reduction of optical density value and quantity of tops up to one or two is registered in all solutions, under study, as content of diluted substance reduces. 

Solutions spectra with ascorbic acid concentration of 1(T and 1(T" mole/l are equal in form and differ from spectra of other dilutions. Lowering of ascorbic acid concentration is not accompanied by unintermpted reduction of optical density value. Irregular growth of absorption in comparison with more concentrated solutions is... 

Community in given structures may be assumed taking into account coincidence of waves length and values of optical density for solutions with concentrations 10 , and 10 mole/1. Gradual reduction of paracetamol concentration in solutions is not accompanied by the same reduction of optical density value. Growth of absorption in comparison with more concentrated solutions is observed for solutions with concentrations 10 , 10and 10 mole/1 (Table 3). All this allows to assume the rise of stmctural changes in these solutions. ... 

The oil chemists have avoided the more serious of these difficulties by alternative methods, using F.A.C. Standards, for example, for different hues. Melvin, et al. (1953) have studied the spectral characteristics of green soybean oil and have suggested optical density values at selected wave lengths which would delimit Grade 2 for crude, refined, refined and bleached oils. Thomson (1953) has further discussed single-number systems with particular reference to the measurement of color of cottonseed and soybean oils. 

Pipette 1, 2, 3, 4, 5 and 10 cm of a 100 ppm solution of p-tert butyl catechol dissolved in purified styrene monomer, into a separate 500 cm volumetric flasks and dilute to the marie with purified monomer. Mix the solutions thoroughly and proceed as described under Method. Plot the optical density values obtained against tl concentration of p-tert butyl catechol (ppm) present in the 500 cm dilutions. 

Discoloration of the dye solution was evaluated both visually and spectrophoto-metrically by optical density value. 

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