Colorimetry Flashcards
Takes advantage of the light-absorbing properties of the substances under study
Colorimetry
The intensity of the color is a measure of the
Amount of substance
One must be certain the compound of interest is the only substance in the mixture that
Absorbs light at the given wavelength
At a specific wavelength, the fraction of light absorbed by a compound is proportional to the concentration of the absorbing compound and the distance that the light passes through the solution.
The Beer-Lambert Law
The value for the absorbance of a 1M solution
Molar extinction coefficient
Values are useful to
Characterize compounds to establish their purity
The Beer-Lambert Law is not valid at
High concentrations of compound
There will be a concentration above which the amount of light is
no longer proportional to the concentration
Compares the absorption of light by an “unknown” amount of the pNP with the absorption of a “known” amount of the pNP
The spectrophotometric analysis of p-nitrophenol (pNP)
Graphing the known amounts of the compound on the x-axis against the absorbance values on the y-axis
Standard curve
Determine the quantity of the unknown pNP using the
Standard curve
Smallest amount of substance that can be detected with confidence
Sensitivity Level
The sensitivity level of a particular assay is dependent upon
The quality of the measuring instrument as well as the confidence level that the investigator places on the acquired data
Measurements are routinely done in
Duplicate or Triplicate
pNP has an intense ______ color in alkaline pH, absorbing at a wavelength of _______ nm.
Yellow
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