Determination of Total Arsenic Using Microwave Digestion Technique-Graphite Furnace Atomic Absorption Spectrophotometry

The aim of this work was to validate the sample preparation using a microwave digestion for determination of total arsenic in a spiked soil. Graphite furnace atomic absorption spectrophotometer (GFAAS) technique was used to determine the total arsenic using palladium nitrate as a modifier agent. The instrumental detection was performed under the condition steps of drying, ashing, atomizing and cleaning to be 100, 1200, 2250 and 2600°C, respectively. The external calibration curve was constructed using the automatic program with the master standard of 20 ppb arsenic solution. It was found that linearity range was in the range of 1 to 20 ppb with R2>0.999. The LOD and LOQ were 0.10 and 1.0 ppb, respectively. Based on two microwave digestion programs, the total arsenic obtained from the preparation method with HF and without HF were also compared. The result showed that the arsenic content obtained from both methods did not significantly different at the 95% confidence limit. The percentage of recovery was 80.3 and 82.3% for the spiked samples of 2.5 and 10 ppb, respectively. The relative standard deviation was 2.15% (n=11). The results of this work confirm that the preparation method using microwave digestion provided the more advantages, such as rapid, a little volume of reagents, completely digestion.