摘要：Atomic absorption spectrophotometry was applied instead of the current colorimetric determination (official) for the rapid determination of microamounts of lead in iron oxide used as a raw material for cosmetics and it was found that this spectrophotometric method was more accurate and speedy than the colorimetry and that the method of standard addition, using non-absorbing line of lead at 2802 Å, was more practical than the method using a masking agent for determination of lead contained in iron oxide. Procedure is as follows : Iron oxide (1-3 grams) is accurately weighed and dissolved in 30 ml of a mixture of hydrochloric acid (1→2)-nitric acid (29 : 1) and diluted to 50 ml with water. To 8 ml each of this iron oxide solution, 2 ml of the standard lead solution containing 0, 2, 4, or 6 μg/ml of lead is added and the content of lead is determined and calculated, using the difference between the absorbance valne at 2833 Å and 2802 Å. This method is recommended for the rapid determination of 1→50 ppm of lead in iron oxide and the coefficient of variation was about 3%.
