Currently

there are few methods to determine the potassium and sodium contents in coal

and the methods are usually of low accuracy. To solve this problem

the national standard method

acid soluble-AAS method and microwave digestion-AAS method were used to detect the potassium and sodium contents in various kinds of low-valence coals

and the precision of the microwave digestion-AAS method was tested. The results show that

by adopting the national standard method

there was a loss of potassium and sodium. While by employing the acid soluble-AAS method

the loss of sodium was comparatively low

that of potassium was relatively high when the potassium and sodium contents in the coal were both high(otherwise it would be low). The microwave digestion-AAS method had high accuracy and precision

which met the requirements for determination of potassium and sodium contents in coal.