13.1 PRECISION, ACCURACY AND DETECTION LIMITS – Single laboratory method performance data are presented in Section 17. LCMRLs and DLs for both NH4OH/(NH4)2SO4 preservative and the CO3-2/HCO3-/(NH4)2SO4 preservative are presented in Table 3. Precision and accuracy data are presented for Cr(VI) fortified into reagent water and preserved with NH4OH/(NH4)2SO4 (Table 4). These data were collected using columns designed for use with an ammonium hydroxide/ammonium sulfate eluent system and columns designed for use with a carbonate/bicarbonate eluent system. Precision and accuracy data are presented for Cr(VI) fortified into two sources of chlorinated ground water, a chlorinated surface water finished with granular activated carbon (GAC) filtration, and a chlorinated surface water finished without GAC filtration. These data were collected using columns designed for an ammonium hydroxide/ammonium sulfate eluent system (Table 5) and columns designed for a carbonate/ bicarbonate eluent system (Table 6). All precision and accuracy data were collected for samples preserved with NH4OH/(NH4)2SO4. Figures 1 through 4 are chromatograms of Cr(VI) in reagent water and drinking water obtained under the conditions employed during method development