Problem Set 3: Standard Addition and Detection Limits
Miller
and Miller Chapter 5, Exercise 5.
There is a 1 in 1000 chance that a person in their
40s with no symptoms has a particular type of cancer.The screening test for this form of cancer
classifies screened patients correctly 90% of the time. A person in their
40s with no symptoms is screened and the results are positive for the
tested cancer.Calculate the
probability that this particular person actually has this type of cancer.
Clearly show all formulas, logic, and calculations.
Miller
and Miller Chapter 5, Exercise 6.
The US Department of Defense is in the process of
disposing of all VX nerve agent chemical warfare stocks to meet Chemical
Disarmament Treaty requirements.Chemical neutralization and incineration are the technologies being
used for disposal.Prior to
operations, one of the on-site laboratories recently developed and
validated standard addition methodology to verify the effectiveness of the
neutralization process in destroying VX. Samples from a recent VX
neutralization process batch were sent to the chemical plant’s
on-site lab for standard addition analysis. The following data were
obtained:
VX Spike Added
( picograms / microliter )
VX Peak Area
0
7,989
5
8,952
10
20,885
15
22,318
20
28,068
30
46,734
Determine the amount of remaining VX in the
chemically neutralized batch, in units of ppb ( picograms / microliter
).
Make a
plot of the data and the standard addition curve.Clearly show your work.
State what you think these laboratory results
indicate about the effectiveness of the chemical plant’s
neutralization process for this batch of VX.