Chemical Reagent Test sensitive at low concentrations Would there be a spot test/tests that can detect either/both of the following molecules at low concentrations? 

The likely concentrations are in the $10{-}\pu{50 mg/L}$ range in an aqueous solution. Ideally, I'd want something that does not need an exotic/expensive instrument.  e.g. a color change or precipitation or conductivity/pH change. 





The background interference: The sample is Terrific Broth which has the following composition:

$\pu{12 g}$ Bacto tryptone
$\pu{24 g}$ Bacto yeast extract
$\pu{4 mL}$ Glycerol
$\pu{100 mL}\ \pu{0.17M}\ \ce{KH2PO4}$ and $\pu{0.72M}\ \ce{K2HPO4}$, sterile, to be prepared separately from the tryptone, yeast extract, and glycerol solution.
Do you have the pure compounds on hand?  If you do, the two target compounds can be crudely isolated by extracting the broth with diethyl ether, concentrating it down, and spotting on SiO2 TLC plate. Compare RF with that of the pure compounds. 
Alternatively, the same general extraction methodology could prepare a sample for GC-MS or crude NMR, if such instrumentation is available