SPECTROPHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF LEAD IN ENVIRONMENTAL WATER SAMPLES IN THE PRESENCE OF MIXED MICROEMULSION

ABSTRACT

A spectrophotometric method is described for the determination of lead(II) in mixed microemulsion. The mixed microemulsion medium composed of cetyl trimethylammonium bromide (CTMAB) and p-iso-octylphenoxy polyethoxyethanol (OP) is used to improve the sensibility of the determination. In Na₂B₄O₇–NaOH buffer (pH 9.50), the reagent 2,6,7-trihydroxy-9-(3,5-dibromo-4-hydroxyphenyl)fluorone (DBH-PF) reacts with lead(II) to form a 3 : 1 purple complex. Under the optimal conditions, Beer's Law is obeyed up to at least 1 µg/ml Pb²⁺ with the molar absorptivity at 580 nm being 1.22 × 10⁵ l mol⁻¹ cm⁻¹. Interfering ions, Al³⁺, Cu²⁺, Cr³⁺, Zn²⁺, Co²⁺, Ni²⁺ and Cd²⁺ can be eliminated easily by sulf-hydryl dextrose gel (SDG) at pH 3.5. The important analytical parameters and their effects on the advised system are investigated. The proposed method has been applied to the environmental water samples, and the results found are satisfactory.

Keywords:

• Lead determination
• Spectrophotometric method
• Mixed microemulsion

Acknowledgment

The research was financially supported by Visiting Scholar Foundation of Key Lab. In University.