Determination of traces of iron in indium phosphide by electrothermal atomic absorption spectrometry combined with solvent extraction.
An electrothermal atomic absorption (ETAAS) method for the determination of traces of iron (0.1-1.0 microgram g-1) in Fe-doped indium phosphide (InP) has been developed. In order to overcome the indium matrix-effect and to achieve a useful detection limit, a preliminary solvent-extraction of Fe(III) with acetylacetone (HAA) is necessary. After sample dissolution with hydrochloric acid (1 + 1) the digest is evaporated to dryness, Fe(II) is oxidized to Fe(III) with nitric acid, the residue is dissolved in 0.01 mol L-1 HCl and the iron is extracted at pH 2.0 with 0.5 mol L-1 HAA in toluene. The organic phase is injected into the graphite furnace and the iron is directly evaluated by external organic standard calibration. The limit of detection (3SB) resulting from further in-situ preconcentration is 0.03 microgram g-1. When the method was applied to the analysis of real samples containing 0.2-0.7 microgram g-1 Fe, the RSD was in the range 8-21%. Results were compared with those independently obtained on the decomposed sample solution with inductively coupled atomic emission spectrometry (ICP-AES). The detection limit of the ICP-AES method, that needs matrix-matched standards, is 0.20 microgram g-1.
Dipartimento di Chimica G. Ciamician, Università di Bologna, Via F. Selmi 2, 40126 Bologna. taddia@ciam.unibo.it
Marco
M
Taddia
Gabriele
G
Bagnoli
Maria Grazia
MG
Cerroni
Roberto
R
Fornari
Giancarlo
G
Righetti
D004784:Environmental Monitoring; D006801:Humans; D007204:Indium / Q000032:analysis*; D007501:Iron / Q000032:analysis*; D010720:Phosphines / Q000032:analysis*; D013054:Spectrophotometry, Atomic / Q000379:methods
D010720:Phosphines; D007204:Indium; D007501:Iron; C090882:indium phosphide