Modification for Pretreatment of Sample in the Determination of Arsenic in Yellow Phosphorus

In the determination of arsenic in yellow phosphorus by the GB standard method (GB 7816-1998), the sample pretreatment was carried out by digestion with HNO3 in an open vessel. As happened actually, this method of sample pretreatment had the defects of time-consuming, accidental error due to contamination and unsafety of self-burning of sample. As a modification, sample pretreatment by reflux digestion was proposed, i.e., the sample (2-3 g) was digested with 60 mL of HNO3(3+2) under refluxing at a heating temperature of 160 ℃. After completion of digestion, the sample solution was used for determination of arsenic by the method of the GB standard. It was shown that the defects of the original method of sample digestion did not happened in the refluxing condensation digestion method and in addition, accuracy of analytical results obtained attained to a same level as that of the Ag-DDTC method.