Determination of lead in seawater by inductively coupled plasma optical emission spectrometry after separation and pre-concentration with cocrystallized naphthalene alizarin

An analytical method for separation and pre-concentration of lead in seawater for determination by inductively coupled plasma optical emission spectrometry has been investigated. Lead was retained in the solid phase (0.5 g) composed of co-precipitated naphthalene and alizarin red. The solid phase quantitatively sorbs Pb(II) at pH 8-9, and the metal was eluted using 5.0 ml of 2 mol 1(-1) nitric acid. The effect of NaCl, KCI, BaCl(2), CaCl(2), Na(2)SO(4), MgCl(2) and Na(3)PO(4) on the sorption of Pb(II) in the solid phase was studied. A set of solutions containing varying amounts of electrolytes (0.5; 1.0; 3.0 and 5.0% m/v) with Ph (50 mug) was prepared and the recommended procedure applied. The Na3(P)O(4) was found to interfere; the other electrolytes did not interfere up to 5% m/v. A pre-concentration factor of 40 was obtained in this analytical procedure. The limit of detection and limit of quantification for Pb(II) were 53 and 176 mug 1(-1), respectively. Lead was determined in seawater samples collected in Salvador city, Bahia, Brazil. The precision, expressed as R.S.D., was 1.8-4.6%, and the recovery of lead added to seawater samples was 95-97%. (C) 2002 Elsevier Science B.V. All rights reserved.