Spatial and temporal non-isothermality as limiting factors for absolute analysis by graphite furnace atomic absorption spectrometry

Abstract

A spatially and temporally isothermal two-step atomiser has been used to measure characteristic masses (m_exp) experimentally. These characteristic masses are compared with theoretical data (m_cal) and with m_exp values obtained using spatially isothermal integrated contact (IC) cuvette equipped and Massmann-type furnaces. The mean and standard deviation of the m_cal/m_exp ratios for 17 elements was 0.98 ± 0.20 with the two-step atomiser, 1.04 ± 0.30 with the IC cuvette and 0.87 ± 0.32 with the Massmann-type furnace. Relative to the Massmann-type furnace, higher m_cal/m_exp ratios for the two-step atomiser can be attributed to improved atomisation efficiencies for elements which are less volatile and/or susceptible to gaseous molecular formation. The poorest performance observed in the Massmann-type furnace can be explained by the occurrence of temperature gradients which decrease the effective tube length. It can be concluded that atomisers providing both spatial and temporal isothermality produce the most reliable m_cal/m_exp ratios.