Making aqueous amino acid solutions?

[mrboswell]

Hi,
Does anyone know of a quick way of dissolving amino acids in water as I having difficulty with some of them, particularly cystine and aspartic acid.
I know I will probably have to adjust them with acid/base but I was wondering if someone had a quick solution that they applied before.
It's just that I'm under pressure for time....
Any help would be grateful.
Thanks

[HW Mueller]

Heat, sonicate, or both, use more H2O.

[Mark Tracy]

Cystine just has poor solubility, and so does tyrosine, but they are more soluble in base than acid. As a general rule amino acids are less soluble near their isoelectric points. For most amino acids, I usually use 0.1 M HCl to make the stock solutions around 20 mM then dilute that to a working concentration in something more agreeable with the chromatography. For the few that have solubility problems, I just make the stocks less concentrated and use more in the dilution.