TLC of spinach pigments

[EeYoRe]

	Me again.  Now I'm having problems making up a phosphate developing
reagent.  It consists of 4 ml concentrated HCl, 4 ml dH2O, 1.28 g ammonium
molybdate*4 H2O, 4 g ferrous sulfate*7 H2O.  THe solution is supposed to be
light brown.  It always turns blue on me (indicating the presence of PO4).
I've tried acid washing all glassware involved, but still can't keep it 
from turning blue.  Any ideas?
				Melissa