Direct analysis of iron in sand by solid sampling electrothermal atomic absorption spectrometry (P4)

Full text: Direct solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS) has deserved attention for trace and ultra-trace elements determination in technological, biological and environmental samples. The reduced sample requirements, the possibility to carry out the sample decomposition inside the graphite furnace, the simplicity and high sensitivity are the main attributes of the SS-ETAAS. In this work the direct determination of iron in sand by using SS-ETAAS was investigated. The sand samples analyzed are used as raw material for glass industry. Each sand sample was directly weighed onto a boat-type platform using microbalance, after then the platform was inserted into the furnace with a manual solid sampling. Samples with different particle sizes were analyzed. Calibration was performed by increasing weighed masses (0.030 - 0.120 mg). Three-field background corrector was used to diminish the sensitivity of the ETAAS, allowing the weigh of high masses. This helps to reach proper representativity. By using one sample with known iron concentration it was possible to perform the ETAAS calibration. Due to the delayed heating rate of the platform boat-type, it was observed that the matrix vaporized after the analyte. However, this temporal separation was not so effective for high masses of sand (> 0,120 mg). Good agreement (95 % confidence level) was obtained for iron determination by comparing this direct method and a reference method. The relative standard deviation was lower than 16 % (n=5). Refs. 2 (author)