# 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.

• Any sort of such a spot test would depend heavily on what else might be in the solution. So what other "stuff" could be in the water? I wouldn't expect either of those molecules to be very water soluble. – MaxW Jun 22 '16 at 19:28
• Thanks @MaxW I've added info about what else could be in the sample. And yes you are right these are not very water soluble although at the low conc. I am expecting they very well might be. This is a conc. of less that 0.01%. – curious_cat Jun 22 '16 at 19:34
• In any case, I want to brainstorm possible test options. At which point I can test them out on control samples of the broth to see what reaction I get. – curious_cat Jun 22 '16 at 19:36
• >Bacto yeast extract || yeah, forget about any meaningful spectroscopy for such low concentrations with this unholy mix in the media. Theoretically speaking, a highly selective molecular recognition agent such as specifically tailored antibody may work, but the R&D required would be quite costly, so unless your needs do not exceed thousands of samples, it is not even worth considering. Other than thatn, GS/GSMS is your best bet. – permeakra Jun 22 '16 at 19:39
• @permeakra Thanks for the insight. That's what I feared. GCMS works well, just that it is slow as number of samples scale. – curious_cat Jun 23 '16 at 2:37