Direct determination of arsenic in high salinity samples by graphite furnace atomic absorption spectrometry

In this study, the sensitive and precise method for the determination of arsenic in samples containing high chlorides concentration was optimized.The standard arsenic solution (50 μg L-1) in solution NaCl (10 gL-1) was used for method optimization.High concentration of sodium chloride in the sample matrix caused high background absorbance which deformed the absorbance of the arsenic. To reduce the background absorption a cool-down step was incorporated into the graphite furnace temperature program before the atomization step. Although we have achieved very good results of arsenic recovery through temperature program improvement, the lifetime of the graphite tube was reduced due to the aggressive composition of the sample matrix. The surface of the graphite tube was significantly damaged after about 50 firing cycles. For this reason, we have combined the cool-down step temperature program with the modification of graphite furnace surface by tungsten carbides (using the aqueous solution Na2WO4.