The final modification was the use of concentrated
HNO3 together with Mg(NO3)2â6H2O (method IV in
Figure 1). This decreases the span of whole ashing time
for the mentioned process by 45% without causing any
losses due to volatilization. The results of the analyses
carried out under these conditions are given in Table
3. As seen, the results are in good agreement at the
95% confidence level (Student’s t test).