commercially available neutralized N-acetyl-L-cysteine solution? - (Nov/13/2007 )

Dear All
I tested the pH of the N-acetyl-L-cysteine powder that we have after being dissolved in water, it was about 2 using litmus paper. I titrated this pH up to about 6-7 and added this solution to my culture. The thing that I am worried about is that I can not exactly determine the pH of the almost neutralized solution because of the small amount of the stock sloution that is diffecult to be adjusted by a pH meter, and accordingly there may be variabilities between different experiments. Is there any commercially available neutralized N-acetyl-L-cysteine solution?? alternatively how can I adjust the pH of a stock solution of a 1-mL volume?
thanks

if pH paper does not get you close enough then you can use a microelectrode to monitor pH while adjusting.

or you can adjust a larger volume and store the rest (if it is stable at the storage conditions (pH, temperature, concentration, in solution, etc.).