Determination of Trace Amount of B in High Purity Si by ICP-MS Using Microwave Assisted Dissolution

A method of ICP-MS for determination of trace amount of boron in high-purity silicon was proposed.Sample of high-purity silicon was digested with mixture of HNO3 and HF in the Mars-5 Microwave digestion system.The solution obtained was used for ICP-MS analysis.Matrix and MS interferences,working condition of the mass spectrograph and working parameter of the microwave digestion system were studied thoroughly and optimized.Beryllium was used as internal standard to compensate for the matrix and MS interferences.The isotopes,11B and 12B were chosen as the analytical isotopes,since no mass spectrometric overlapping interferences due to co-existing isomers and multi-atomic ions were observed with these 2 isomers.Tests for recovery and precision of the method were performed,and results obtained were as follows:values of recovery and RSD′s (n=8) found were in the ranges of 98%-110% (for 11B),96%-107% (for 12B) and 2.9% (for 11B),2.8% (for 12B) respectively.Values of detection limit found were 4 ng·L-1 (for 11B) and 8 ng·L-1 (for 12B).