When Googling around for methods to remove pesticides from fruits and vegetables, a study commonly referred to from some news sites (e.g. here and here ) is one where soaking apples in a sodium bicarbonate solution was shown to effectively remove pesticides (the study was conducted using the pesticides phosmet and thiabendazole), more effectively then a certain method where just water was used.

My question is what would be the likely mechanism for a sodium bicarbonate solution to remove pesticides better than plain water (which was also tested in the mentioned study) and what that says about the applicability of the study to other pesticides (is the result likely to be applicable just to the two pesticides tested, or to be quite general?)

Here is my guess; a guess from just dabbling in chemistry here and there (I'm a computer programmer and by no means an expert on chemistry). The guess is that the additional hydroxide ions in the solution, created due to the sodium bicarbonate having been added, make hydrolysis of the pesticides more likely because the hydroxide can do a "nucleophilic attack".

  • $\begingroup$ Hydrolysis is certainly a possibility. It will depend on the structure of the pesticide molecule as to how suspectible it is to this process. Phosmet - quite possibly so. Thiabendazole - not very much, more likely removed by a mild acid (vinegar?) wash as it is basic. $\endgroup$
    – Waylander
    Commented Mar 13, 2019 at 9:49
  • $\begingroup$ The $\ce{P-S}$ is ~half as strong as the $\ce{P-O}$ bond so it looks like $\ce{OH-}$ catalyzed hydrolysis would readily occur in phosmet. $\endgroup$
    – Buck Thorn
    Commented Mar 13, 2019 at 15:25


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