RHODIUM, 1000 mg/L. Dissolve 0.412 g of ammonium hexachlororhodate trihydrate, (NH4)3RhCl6•3H2O, in a minimum volume of 10% (v/v) HCl and dilute to 100 mL with 10% (v/v) HCl. Dilute Rh standards should also contain 10% (v/v) HCl. The use of a very lean flame is