Lactic acid vs lactate in sweat - (Jan/24/2011 )

I want to measure the pH of sweat in order to estimate the anaerobic threshold by detection of lactic acid.

Many references point out that it's lactate, not lactic acid, that is found in sweat.

However, according to this article:

http://www.bentham.org/open/tocorrj/articles/V003/38TOCORRJ.pdf

Artificial sweat is synthesized with lactic acid as per standard ISO 3160-2, (20g/l NaCl, 17.5 g/l NH 4 Cl, 5g/l acetic acid and 15 g/l d,l lactic acid with the pH adjusted to 4.7 by NaOH).

Also, I want to measure the pH by the potential sensed by copper-zinc electrodes in series etched on a printed circuit board. Would that work? Thanks.

Lactate = the free base of lactic acid... i.e. CH₃CH₂COO^- in solution. As a crystal it would need the extra H CH₃CH₂COOH to form lactic acid.