Reagents and Test Media
The following reagents and test media are required for the Sodium Rhodizonate Test:
- Saturated solution of sodium rhodizonate dissolved in distilled or deionized water
- Buffer solution of 2.8 pH consisting of sodium bitartrate and tartaric acid in distilled or deionized water
- Solution of hydrochloric acid (5 percent) in distilled or deionized water
- A known source of lead
Sodium Rhodizonate Solution
Add a sufficient amount of distilled or deionized water to a small amount of sodium rhodizonate in a small beaker to form a saturated solution that is approximately the color of dark tea. The solution is saturated if a slight amount of sediment remains in the beaker after stirring with a glass stirring rod. The solution is usually ineffective after one hour.
2.8 pH Buffer Solution
- Dissolve 29.3 grains (1.9 grams) of sodium bitartrate and 23.1 grains (1.5 grams) of tartaric acid per 100 mL of distilled or deionized water. Heat on a hot plate while agitating with a magnetic stirrer to create the solution quickly.
- Store in a sealed container labeled according to laboratory protocol. The shelf life of the solution is limited.
Hydrochloric Acid Solution
- Combine 5 mL of concentrated hydrochloric acid with 95 mL of distilled or deionized water. Carefully pour the acid into the water to preclude spattering of acid.
- Store in a sealed container labeled according to laboratory protocol.