FAAS Determination of K and Na in Coke Ash with Microwave Assisted Sample Digestion

Sample of coke ash (0.100 0 g) was digested with 8 mL of mixed acid of HF and HNO3 (1+3), and the contents of K and Na in the sample solution were determined by FAAS. Linear relationships between values of absorbance and mass concentration of K and Na were obtained in the ranges within 4 mg·L-1 and 2 mg·L-1, with detection limits (3σ) of 12 μg·L-1 and 6 μg·L-1, respectively. The proposed method was applied to the analysis of CRM′s, giving results in consistency with the certified values. Values of RSD′s (n=11) found were in the ranges of 2.7%-3.8% for K and 1.3%-3.1% for Na.