Evaluation of two atomisation modes for direct determination of molybdenum in complex matrices by ultrasonic slurry sampling-electrothermal atomic absorption spectrometry

摘要

Tube wall (TWA) and L'vov platform (LPA) atomisations were compared for the direct determination of molybdenum (Mo) in coal fly ash by slurry sampling-electrothermal atomic absorption spectrometry (ETAAS).For both atomisation modes eight chemical modifiers were tested,namely HNO_3,Pd(NO_3))2,Mg(NO_3)_2,Pd + Mg(NO_3)_2,reduced Pd,BaF_2,Ir and HF.The interfering effects of major and minor concomitants of samples on Mo signals and memory effects were also evaluated.BaF2 and Pd(NO_3)_2 + Mg(NO_3)_2 mixture were selected for TWA and LPA,respectively.Standard addition calibration is needed in both cases.The best peak performance,memory effect reduction,within-run precision (6% versus 9% R.S.D.),and sensitivity (m_a = 7.5 pg versus 15.2pg) were achieved with TWA compared to LPA.Both atomisation modes gave good analytical recoveries (94-102%),but the analysis of a certified coal fly ash (NIST SRM 1633a) only was accurate using TWA.Additionally,the urban dust NIST SRM 1629a was analysed.