LEAD DETERMINATION RAPID FIELD TEST FOR TRACE LEAD IN GASOLINE: ASTM D3348
EXPLANATION
This test method is based on the use of Mobil lead test kit and is intended for field use by nontechnical personnel, for the quantitative measurement of lead in unleaded gasoline in the range from 2.64 to 26.4 mg Pb/L. This test method is applicable to all commercial gasolines and responds to all types of lead alkyls as well as other organic and inorganic forms of lead. This is a screening test and is not intended to replace other lead measurement methods.
TEST SUMMARY
The gasoline sample is treated with iodine and tetraethyl ammonium chloride in chloroform and subjected to ultraviolet light. The lead alkyls form water soluble lead alkyl iodides, which are extracted out by shaking with an aqueous ammonium nitrate solution. The aqueous extract is filtered into a solution of 4-(2-pyridylazo)-resorcinol di-sodium salt (PAR) and ammonium hydroxide. The lead-PAR complex is measured colorimetrically at 490 nm using a previously prepared calibration curve. PAR reagent also reacts with many other transition metals forming colored complexes; however, none of these metals are normally present in a soluble form in gasoline.
TEST PRECISION
This test method has a repeatability of 2.64 mg/L and a reproducibility of 5.28 mg/L.
