A sapphire tube atomizer for on-line atomization and in situ collection of bismuthine for atomic absorption spectrometry

Abstract

Sapphire was tested as a new material for volatile species atomizers. Bismuthine was chosen as a convenient model for volatile species. The fundamental approach adopted was to compare the performance of a sapphire-based atomizer with a quartz atomizer in both modes of operation (on-line atomization versus in situ collection) under equal experimental conditions including design and size of both atomizers. Only the temperature range compatible with the quartz atomizers (up to 1000 °C) was investigated. The employment of the modular atomizer design made it possible to comply with the principal requirement of the same design and size of both atomizers: both the atomizers differed only in the material of the exchangeable optical tube (a plain tube with a central orifice). No significant difference between quartz and sapphire regarding atomization as well as in situ collection was found and virtually the same analytical characteristics were achieved. Excess of O₂ over H₂ was employed for efficient trapping and efficient and very fast volatilization was achieved by means of auxiliary H₂. Under optimized conditions the collection efficiencies of 97 ± 3% and 94 ± 4% were achieved for the sapphire and quartz tube, respectively, and the limits of detection of around 30 pg ml⁻¹ were achieved for 1 ml sample volume. The advantages and future prospects of the use of the sapphire tube are highlighted and discussed.