Efficiency of solid$-$phase microextraction. Equation $24-9$ gives the mass of analyte extracted into a solid$-$phase microextraction

fiber as a function of the distribution constant between the fiber coating and the solution:

$m=\frac{K_D{V}_f{C}_u{V}_a}{K_D{V}_f+V_n}$

where $m$ is the mass of the analyte in micrograms, $V_f$ is the volume of film on the fiber, $V_s$ is the volume of solution being

extracted, $c_0$ is the initial concentration $(\frac{g}{m}L)$ of analyte, and $K_b$ is the distribution constant for solute between the film and

the solution.

A commercial fiber with a $100-m-$thick coating has a film volume of $6\mathrm{.}9{10}^{-4}mL.$ Suppose that the initial concentration of

analyte in solution is ${}_0=0\mathrm{.}10\frac{g}{m}L(100ppb).$ Use a spreadsheet to prepare a graph showing the mass of analyte extracted

into the fiber as a function of solution volume for distribution constants of $10000,5000,1000,$ and $100.$ Let the solution volume

vary from $0$ to $100mL.$

Evaluate the limit of Equation $24-9$ as $V_a$ gets bigger relative to $K_D{V}_f.$ What is the limit when $K_D=100$ and when

$K_b=10000g?$

Doe

$1$

I

Incornect

What percentage of the analyte from $10\mathrm{.}0mL$ of solution is extracted into the fiber when $K_D=100$ and when $K_D=10000?$

$K_D=100$ percentage extracted:

$K_D=10000$ percentage extracted