however regarding purity food grades are usually held to higher standards so I would assume that this would increase its relative price.
I disagree, are you suggesting that food grade GABA would be more pure than an analytical grade i.e. Sigma's 99%, and therefore more expensive?
Food Grade = lots of impurities / lower price
99% = few impurities / higher price
Just because humans consume this product does not mean it has to be highly pure. Your body does not care if the GABA contains 20% impurities, however your reaction, analysis, column, or what have you may be very sensitive to GABA containing 2-3% of impurities. Does that make more sense now?
regards,
m_e