Accuracy of the method was studied by performing a standard additions study to evaluate the recoveries of lithium from a series of filter flags that were spiked with lithium in the range from 0 to 1.0 g per flag. Table 3 summarizes the results of this study, which indicate acceptable recovery and linearity for the procedure, with a slope of 1.047 (equivalent to a recovery of 104.7%) and a correlation coefficient of 0.9998.