BLD 313 EXAM 3 QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++
Give an example of semi-quantitative test result?
3+
reagent blank
subtracts the color contribution of the reagent
specimen blank
subtracts the light absorption of patient serum.
Example of light based signal
scatter
downward shift
underestimates concentration
relationship between lower limit of detection and reagent blank
The distance between the lowest limit of detection and a reagent blank need to be at
least 2SD+2SD.
What is the molar absorptivity (ε) of a compound which produces an absorbance
(A) of 0.250 at a concentration of 0.200 M in a cuvette path width of 2 cm?
0.625 /(M• cm)
A chromophore has a molecular weight of 150 g/mol. When 20.0 mg of this
substance is placed in 500 mL of water, it produced an absorbance of 0.250. What
is the molar absorptivity (ε) of this compound? (The cuvette path width is 1 cm).
, 938 /(M• cm)
The concentration of a solution is 10.0 M. It has an absorbance of 0.200 when
placed in a 1.00 cm cuvette at the wavelength of 250 nm. What would be the
absorbance if the solution is 5.00 M?
0.100
A compound has a molar absorptivity of 1.50 x 102 /(M• cm) . if 1.0 mL of a
solution containing this compound is placed in 5.0 mL of water, this final solution
produced and absorbance of 1.500. What is the concentration of this compound
in the original solution? (cuvette = 1.0 cm)
0.060 M
If a two component mixture has an absorbance of 0.70 at 350 nm and 0.79 at 400
nm, what is the concentrations of compound A? Assume a 1.0 cm cuvette and the
following:
Compound A: λ = 350nm, ϵ = 1.0 x 104 L/mol∙cm; λ = 400nm, ϵ = 5.0 x 103
L/mol∙cm
Compound B: λ = 350nm, ϵ = 7.5 x 103 L/mol∙cm; λ = 400nm, ϵ = 1.3 x 104
L/mol∙cm
3.4 x 10-5 M
How do we choose the type of cuvette in spectrophotometry
depends on the wavelength we need to detect.
narrow band pass
Increases specificity and sensitivity of spectrophotometric analysis
COMPLETE SOLUTIONS GRADED A++
Give an example of semi-quantitative test result?
3+
reagent blank
subtracts the color contribution of the reagent
specimen blank
subtracts the light absorption of patient serum.
Example of light based signal
scatter
downward shift
underestimates concentration
relationship between lower limit of detection and reagent blank
The distance between the lowest limit of detection and a reagent blank need to be at
least 2SD+2SD.
What is the molar absorptivity (ε) of a compound which produces an absorbance
(A) of 0.250 at a concentration of 0.200 M in a cuvette path width of 2 cm?
0.625 /(M• cm)
A chromophore has a molecular weight of 150 g/mol. When 20.0 mg of this
substance is placed in 500 mL of water, it produced an absorbance of 0.250. What
is the molar absorptivity (ε) of this compound? (The cuvette path width is 1 cm).
, 938 /(M• cm)
The concentration of a solution is 10.0 M. It has an absorbance of 0.200 when
placed in a 1.00 cm cuvette at the wavelength of 250 nm. What would be the
absorbance if the solution is 5.00 M?
0.100
A compound has a molar absorptivity of 1.50 x 102 /(M• cm) . if 1.0 mL of a
solution containing this compound is placed in 5.0 mL of water, this final solution
produced and absorbance of 1.500. What is the concentration of this compound
in the original solution? (cuvette = 1.0 cm)
0.060 M
If a two component mixture has an absorbance of 0.70 at 350 nm and 0.79 at 400
nm, what is the concentrations of compound A? Assume a 1.0 cm cuvette and the
following:
Compound A: λ = 350nm, ϵ = 1.0 x 104 L/mol∙cm; λ = 400nm, ϵ = 5.0 x 103
L/mol∙cm
Compound B: λ = 350nm, ϵ = 7.5 x 103 L/mol∙cm; λ = 400nm, ϵ = 1.3 x 104
L/mol∙cm
3.4 x 10-5 M
How do we choose the type of cuvette in spectrophotometry
depends on the wavelength we need to detect.
narrow band pass
Increases specificity and sensitivity of spectrophotometric analysis
