Question

Analyze the data below for the concentration of a poison, arsenic, in plasma as a function of time. This problem involves the same concepts as administration of a drug but is termed toxicokinetics rather than pharmacokinetics. The objective of this analysis is to determine the kinetic order of the clearance rate of arsenic from plasma. Modeling this as a simple batch system, the general description is: dC/ dt = - k*C^n Where C is the plasma concentration of arsenic, t is time, k is a rate coefficient, and n is the reaction order with respect to arsenic concentration. The following experimental data are available in table

time (h) 5 - 6 - 8 - 12- 24

As (μM) 68 - 34 - 16 - 8 - 4

(a) Test whether a zero-order kinetic model applies by plotting the rate (dC/dt) versus time. If zero-order kinetics apply, this rate should be constant.

(b) Test whether a first-order kinetic model applies by plotting the natural logarithm of the rate (ln(dC/dt)) versus time. If first-order kinetics apply, this analysis should yield a straight line. (c) Perform a general analysis to determine the reaction order by plotting the natural logarithm of the rate versus ln(C). If this analysis yields a straight line, then the reaction order is given by the slope of the line.

(d) What kinetic model do you think is best for this system?

Answer 1

The slope is 0.983/hr

from the plots, the first order kinetic model explains the data