IAS Aroid Quasi Forum

About Aroid-L
 This is a continuously updated archive of the Aroid-L mailing list in a forum format - not an actual Forum. If you want to post, you will still need to register for the Aroid-L mailing list and send your postings by e-mail for moderation in the normal way.

  RE: Re: Re: GA3 in seed germination
From: Ron McHatton rmchatton at photocircuits.com> on 2001.05.30 at 14:35:47(6613)
Not to continue beating the dead horse, but I can't stand this anymore. GA
is slightly soluble in water and should dissolve on its own to levels which
will be effective. The problem is the rate at which it dissolves, and the
fact that the powdered free acid is hydrophobic which makes wetting of the
salt difficult. The free acid is soluble in methanol, ethanol, acetone and
aqueous solutions of sodium bicarbonate. If you go the route of dissolving
first in alcohol, you should dissolve the GA in a very small amount of the
alcohol (if you use drinkable stuff, you need the proof as high as possible
or its just trying to dissolve GA in more water), then dilute to final
working strength. At concentrations in the ppm range, the GA will not
reprecipitate when water is added. That trick is used with alot of
sparingly to slightly water soluble organics. You can't get them to
dissolve, but once you do dilute solutions are pretty stable.

GA is also soluble in water solutions of sodium bicarbonate. I believe
this or sodium acetate is the medium that formed the basis of the water
miscible material someone else wrote about. Anyway, sodium bicarbonate is
easier to get than potassium hydroxide and no where near as corrosive. The
pH of a 7 gram per liter solution of sodium bicarbonate is about 8.4. You
can double that concentration and not move the pH very much. Its a
little high, but not so high that any plants would be damaged and you don't
get into the vicious cycle of pH up and down trying to control KOH.
Solubility as well as the rate at which the material dissolves is
dependent on temperature and the bicarbonate solution. You shouldn't have
a problem with a final bicarb concentration around 7 g/l. I would prepare
a small amount of sodium bicarbonate solution that is on the order of ten
times that concentration, warm it slightly and dissolve the GA in that
concentrated solution. Dilute the concentrate by a factor of 10 and apply.

Ron McHatton

Note: this is a very old post, so no reply function is available.