Tin determination in marine sediment, soil, coal fly ash and coal slurried samples by hydride generation-electrothermal atomic absorption spectrometry

Different procedures of tin hydride generation from aqueous and acidified slurries of marine sediment, soil, coal fly ash and coal samples, coupled to electrothermal atomic absorption spectrometry were optimised by using factorial designs. A batch mode generation system and Ir-treated graphite tubes were used for the hydride generation and atomisation, respectively. Eight variables, affecting the hydride generation and hydride transport efficiency (hydrochloric acid and sodium tetrahydroborate concentrations, particle size, acid volume and argon flow rate), the hydride trapping efficiency (trapping temperature and trapping time) and the atomisation efficiency (atomisation temperature) were studied and optimised. In addition, acid pre-treatment procedures assisted by ultrasonic energy were used for soil and coal matrices, to obtain acidified slurries and acid leachates. The involved variables were hydrochloric and nitric acid concentrations, exposure time to ultrasound, particle size and leaching solution volume. Adequate accuracy (41.5±0.8 and 1.4±0.2 mg kg⁻¹, for PACS-1 (sediment marine) and NIST-1633b (coal fly ash), respectively) were obtained by using aqueous slurry reference materials. In addition, values of 6.2±0.6 and 1.2±0.1 mg kg⁻¹ were assessed by analysing GBW-07401 (soil) and NIST-1632c (coal) certified reference materials.