Gradient absorbance trace

Figure 4.5. The gradient absorbance trace used to measure the system dwell volume of a Waters Alliance system. Inset shows the intersection point marking the gradient onset.

Figure 9-15. Poly I,G-effected separation of the complementary strands of A phage DNA in preparative and analytical CsCl gradients. Upper trace represents the absorbance (260 nm) of the 4-drop (50 tl) fractions (total volume 2.5 ml) measured in a 20 /u.1 microcuvette (2 mm light path). Lower trace represents the microdensitometric tracing of the photograph of the same undiluted material banded in the analytical ultracentrifuge (4°C, 3 mm cell) with added density marker DNA (Cytophaga johnsonii, 1.6945 g/cm dashed line). Peak C contains the DNA strands C, which preferentially bind poly I, G the complementary strands W band under peak W. Symbols dN and NN indicate the positions (densities) of the denatured and native Acbj DNA, respectively. [From Z. Hradecna and W. Szybalski, Virology, 32 633 (1967).]...

Fig. 39.3 LC PDA analysis, UV (297 nm) trace (using 1 mL/min gradient elution from 90% H20/MeCN (0.01% TFA) to MeCN (0.01% TFA) over 30 minutes followed by a 5 minute flush with MeCN on a Phenomenex Onyx CiglOO x 4.6mm column) showing a) non-polar, b) intermediate, c) polar fractions and d) characteristic absorbance profile of parotoid secretion from B. marinus.

Initial reaction rates are often estimated from the steepest tangents to absorbance/time traces. These initial gradients (absorbanee units/sec) are easily converted into Ms" units by using the known molar absorptlvities of products and reactants. Alternatively, absorbanee (Z))/Time (T) plots can be fit to a funetion (1.9) leading to (1.10) and (1.11)... 

---