8.2.2 In most cases, matrix spikes should be added at a
concentration equivalent to the corresponding regulatory
level. If the analyte concentration is less than one half
the regulatory level, the spike concentration may be as low as one half of the analyte concentration, but may not
be not less than five times the method detection limit. In
order to avoid differences in matrix effects, the matrix
spikes must be added to the same nominal volume of TCLP
extract as that which was analyzed for the unspiked
sample.