Use of high resolution continuum source atomic absorption spectrometry as a detector for chemically generated noble and transition metal vapors

Vapor generation and atomization conditions in a heated quartz tube to detect Ag, Cd, Co, Cu, Ni and Zn using High Resolution Continuum Source AAS (HRCSAAS), were optimized. Vapors were generated after mixing acidified Solutions containing 8-hydroxiquinoline (oxine) with sodium tetrahydroborate. Afterwards, they were swept to the heated quartz cell by an argon flow. Reaction loop size and temperature of the quartz cell were optimized for each element. A temperature of 960 degrees C was selected as a compromise value to detect most of the metals. Afterwards, a Plackett-Burmann design was proposed to select which parameters were most important. Type of acid and its concentration were the most statistical significant variables. Optimum conditions for sequential detection of Cd, Cu, Ni and Zn were: 1 mg L-1 Co as catalyst, 250 mg L-1 oxine, 0.6 M nitric acid, 1.75% (w/w) sodium tetrahydroborate (prepared in 0.4 (w/v)% NaOH), a reaction loop of 250 mu l, and a 25 L h(-1) carrier At flow. Ag and Co were each detected in their own optimized conditions. Analytical performance of the system was evaluated in connection with a selected pixel number. and spectral correction was used to eliminate NO absorption bands interference in Zn detection. Detection limits were in the range of 1.5-18 mu g L-1 for Ag, Cu, Cd and Zn, whereas sensitivity was worst for Co (169 mu g L-1) and Ni (586 mu g L-1). Atomization in a quartz cell of Co and Ni volatile species, generated by an addition of sodium tetrahydroborate to an acidified Solution of the analytes, was reported for the first time in this paper. Precision expressed as RSD(%) had Values lower than 10% except for Ni. (C) 2009 Elsevier B.V. All rights reserved.