pling Learning The data in the table at the right show a calibration curve for t

Question

pling Learning The data in the table at the right show a calibration curve for the determination of RNA from its absorbance at 260 nm. RNA Absorband 0.00 10.74 21.48 32.22 42.96 at 260 nnm 0.180 0.424 0.678 1.027 1.265 Use a spreadsheet and the least-squares method to determine the slope and intercept of the best straight line fit to the calibration curve. (Do not subtract the blank reading when creating your calibration curve.) Number slope= 110.277 labs, Number intercept0.117 Using the slope and intercept of the calibration curve, determine the quantity of RNA in a sample that gives an absorbance of 0.58. Number mass RNA = 1116.26 Incorrect

Explanation / Answer

Absorbance (A) and concentration C ( expressed in mass) are related as

A= ebC, b =path length and e= molar extinction coefficient.

so a plot of A vs c will be straight line.

so a plot of A vs C is generated and shown below.

from the plot, Absorbance= 0.025* mass of RNA(ug)+0.160 (1)

hence the slope is 0.025/ug and intercept =0.160

given A= 0.58, from Eq.1, 0.58= 0.025* mass of RNA(ug)+0.160

mass of RNA (ug)= (0.58-0.160)/0.025 =16.8 ug

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