Highly sensitive spectrofluorimetric determination of trace amounts of lead with a new fluorescent reagent, 2-hydroxy-1-naphthaldehydene-8-aminoquinoline
Hj. Wang et al., Highly sensitive spectrofluorimetric determination of trace amounts of lead with a new fluorescent reagent, 2-hydroxy-1-naphthaldehydene-8-aminoquinoline, ANALYST, 126(7), 2001, pp. 1164-1167
A new fluorescent reagent, 2-hydroxy-1-naphthaldehydene-8-aminoquinoline (H
NAAQ), was synthesized. The fluorescent reaction of this reagent with lead
was also studied. Based on this chelation, a highly sensitive spectrofluori
metric method was developed for the determination of trace amounts of lead
in a water-ethanol (5 + 1, v/v) medium at pH = 9.4. Under these conditions,
the Pb-HNAAQ complex has excitation and emission maxima at 398 and 450 nm,
respectively. The linear range of the method is from 0 to 100 mug l(-1) an
d detection limit is 0.28 mug l(-1) of lead. Interference of other ions was
studied. In strongly basic media most interfering metal ions form precipit
ates of hydroxides or oxides and can be removed efficiently through filtrat
ion while the residual cations can be removed with a cation-exchange resin.
Hence, the selectivity of the method can be increased considerably. The pr
ocedure can easily be performed and affords good precision and accuracy. Th
e method was successfully applied to the determination of lead in wheat and
rice flour.