Use reagents low in aluminum, and aluminum-free distilled water.
a. Stock aluminum solution: Use either the metal (1) or the salt (2) for preparing stock
solution; 1.00 mL = 500 µg Al:
1) Dissolve 500.0 mg aluminum metal in 10 mL conc HCl by heating gently. Dilute to 1000
mL with water, or
2) Dissolve 8.791 g aluminum potassium sulfate (also called potassium alum),
AlK(SO4)2⋅12H2O, in water and dilute to 1000 mL. Correct this weight by dividing by the
decimal fraction of assayed AlK(SO4)2⋅12H2O in the reagent used.
b. Standard aluminum solution: Dilute 10.00 mL stock aluminum solution to 1000 mL with
water; 1.00 mL = 5.00 µg Al. Prepare daily.