AFS Determination of Arsenic and Antimony in Soil with Microwave Assisted Sample Digestion

AFS was applied to the determination of arsenic and antimony in soil.The sample was first treated with a mixed acid of HCl+HNO3+H2O (3+1+4) for 30 min at room temperature and then digested in the microwave digestor under the prescribed program.A mixed solution of thiourea and ascorbic acid was added to the sample solution which was used for AFS determination after diluting to 10.0 mL.A aliquot of 2 mL of the supernatant sample solution was injected into the reactor to react with the reductant (KBH4 solution) and the hydrides of arsenic and antimony were carried over into the quartz atomizer by argon.Details of working condition of the AFS instrument were given.Values of detection limit (3S/N) for both As and Sb were found same as 0.050 μg·L-1.Recovery of the method was tested at 3 concentration levels by adding standard solutions of As and Sb to a soil sample as matrix,values of recovery found were in the ranges of 99.5% to 104.0% (for As) and 98.5% to 99.5% (for Sb).