Table 1.
Serum cortisol dilutions used for reportable range/linearity, precision, recovery, and detection limit studies.
| Level | Concentration, nmol/L (μg/dL) | Starting solution | Diluted with: | Studies* |
|---|---|---|---|---|
| L10: high pool | 1,380 (50) | 500 µL of FIS | 9.5 mL of L1 | Recovery |
| L9 | 1,035 (37.5) | 750 µL of L10 | 250 µL of L1 | Recovery |
| L8 | 552 (20) | 400 µL of L10 | 600 µL of L1 | Recovery |
| L7 | 345 (12.5) | 250 µL of L10 | 750 µL of L1 | Recovery |
| L6 | 172 (6.25) | 125 µL of L10 | 875 µL of L1 | Recovery |
| L5 | 69 (2.5) | 50 µL of L10 | 950 µL of L1 | Recovery |
| L4 | 38.6 (1.4) | 28 µL of L10 | 972 µL of L1 | Recovery |
| L3 | 13.8 (0.5) | 100 µL of SIS | 900 µL of L1 | DLS |
| L2 | 6.9 (0.25) | 50 µL of SIS | 950 µL of L1 | DLS |
| L1: low pool | Very low (undetectable) | Matrix | — | DLS |
| L0 (saline) | Blank | Saline | — | DLS |
Dash (—) = no dilution; DLS = detection limit study; FIS = first intermediate solution (1,000 μg/dL); SIS = second intermediate solution (5 μg/dL).
*
Linearity and precision were performed for all dilution levels.