The levels of recovery and relative standard deviation (RSD)
are given in Table 3. The average recoveries of the spiked
standards for the analytes were 82.3-94.2% with average RSDs
of 1.2-4.0%. The CPE method was compared with the LLE
method. As summarized in Table 3, there was no significant
difference between the proposed method and the reference
method (NY/T 761-2008).