A Simple Spectrophotometric Method for the Determination of Aluminum in Some Environmental, Biological, Soil and Pharmaceutical Samples Using 2-Hydroxynaphthaldehydebenzoylhydrazone

Abstract

A simple ultra-trace, and highly selective non-extractive spectrophotometric method is presented for
the rapid determination of aluminum at trace levels using 2-hydroxynaphthaldehydebenzoylhydrazone (HNPBH) as a new spectrophotometric reagent (max = 412 nm) in slightly acidic solution
(1.5×10-5-1.25×10-4 mol L-1 H2SO4) in 50% N,N-dimethylformamide (DMF) medium. The reaction is
instantaneous and absorbance remains stable for over 24 h. The color system obeys Beer’s law from
0.01-2.0 mg L-1 having detection limit of 1 µg L-1 and RSD 0-2%. The average molar absorptivity and
Sandell’s sensitivity were found to be 2.21104
L mol-1 cm-1 and 6 ng cm-2, respectively. The
stoichiometric composition of the chelate is 2:3. The interference from over 50 cations, anions, and
complexing agents (tartrate, oxalate, citrate, EDTA, DMG, 1.10 phenanthrolin, oxine, phosphate, thiourea, SCN-
) has been studied at 1 mg L-1 of Al. The method was successfully applied to some certified
reference materials (alloys and steels), environmental waters (inland and surface), biological samples
(human blood, urine and gallstone), soils, pharmaceutical samples (entacyd and almasil) and complex
synthetic mixtures. The method has high precision and accuracy (s = ±0.01 for 0.5 mg L-1).