In wet digestion methods of plant sample, HClO4 acid prevents the excessive frothing which occurs frequently when HNO3 or H2SO4 acid is used singly.  For more references you consult the attached file.

dear Debashis roy,  thank you for your answer

Percholric acid also play a role of reducing or release compounds bound to protein in sample you are processing in cas eyou are working on plasma.

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