The effectiveness of disinfectants can be measured in DRT values. The DRT values for contact lens disinfectants against Serratia marcescens are as follows:

$\backslash$table$[[$Disinfectant$,$DRT Value $($min$),$Disinfectant,DRT Value $($min$)],[$Chlorhexidine$,0\mathrm{.}005\%,2\mathrm{.}8,$Thimerosal, $0\mathrm{.}002\%,138\mathrm{.}9],[$Hydrogen peroxide, $3\%,3\mathrm{.}1,$Polyquaternium$-1,0\mathrm{.}001\%,383\mathrm{.}3]]$

Which disinfectant is most effective?

What is the minimum time that lenses with ${10}^2$ bacteria should be soaked in chlorhexidine?

In polyquaternium$-1?$

What if the lenses are contaminated with Staphylococcus or Acan"

Why isn't a higher concentration of disinfectant used ${?}^{?}$