Enhancement of the atomic absorbance of Cr, Zn, Cd, and Pb in metal furnace atomic absorption spectrometry using absorption tubes

•The absorption tube achieved the enhancement of atomic absorbance in MFAAS.•The tube-type absorption tube was effective for Zn and Cd.•The intensities of Zn and Cd using the absorption tube were double of those measured without the tube.•The method was successfully applied in the determination of Zn in tap water.

Trace amounts of Cr, Zn, Cd, and Pb were determined by metal furnace atomic absorption spectrometry using absorption tubes. Various absorption tubes were designed as roof- and tube-types, and fixed above the metal furnace in order to extend the light path length. Aqueous standards and samples were injected in the metal furnace and atomized in a metal atomizer with an absorption tube (6 cm length, 15.5 mm diameter). The used of an absorption tube resulted in an enhancement of the atomic absorbance. The ratios of absorbance values with and without the roof- and tube-type absorption tubes were 1.33 and 1.11 for Cr; 1.42 and 1.99 for Zn; 1.66 and 1.98 for Cd; and 1.31 and 1.16 for Pb, respectively. The use of an absorption tube was effective for Zn and Cd analysis, as the absorbance values for these low boiling point metals doubled. The proposed method was successfully applied in the determination of Zn in tap water.

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