TABLE 1.
Ceftriaxone liquid chromatography-mass spectroscopy assay characteristics at different concentrations when measured from plasma and dried blood spots
| Parameter and/or sample sourcea | Value for the parameter with: |
|||||
|---|---|---|---|---|---|---|
| Cefazolin (1.5 mg/liter)b | Ceftriaxone at the indicated concn (mg/liter) |
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| 5 | 10 | 20 | 50 | 200 | ||
| Plasma | ||||||
| Matrix effect (% ± SD, n = 5) | 88.5 (±8.2) | 104.1 (±4.6) | 101.6 (±14.5) | 90.4 (±8.2) | ||
| Process efficiency (% ± SD, n = 5) | 96.3 (±11.9) | 103.1 (±5.7) | 107.6 (±6.9) | 96.8 (±5.1) | ||
| Absolute recovery (% ± SD, n = 5) | 109.0 (±13.9) | 97.3 (±8.1) | 108.9 (±13.2) | 106.3 (±11.5) | ||
| Interday variation (RSD%, n = 5) | 6.5 | 5.9 | 4.8 | 3.9 | ||
| Intraday variation (RSD%, n = 15) | 7.8 | 6.3 | 5.4 | 4.9 | ||
| Accuracy (% ± SD, n = 20) | 102 (±9.4) | 96 (±8.7) | 105 (±7.5) | 98.2 (±8.6) | ||
| Protein binding (% ± SD, n = 5)c | 94.5 (±0.2) | 95.3 (±0.1) | 90.1 (±0.2) | |||
| Red cell partitioning ratio (±SD, n = 5) | 0.55 (±.09) | 0.61 (±.06) | 0.57 (±.08) | |||
| Dried blood spots | ||||||
| Matrix effect (% ± SD, n = 5) | 82.6 (±3.5) | 103.5 (±6.1) | 112.6 (±7.7) | 109.2(±3.1) | ||
| Process efficiency (% ± SD, n = 5) | 80.1 (±2.6) | 86.4 (±4.6) | 93.9 (±6.9) | 92.6 (±2.2) | ||
| Absolute recovery (% ± SD, n = 5) | 97.9 (±1.9) | 83.5 (±2.0) | 83.3 (±2.7) | 84.8 (±2.1) | ||
| Interday variation (RSD%, n = 5) | 5.9 | 6.8 | 4.7 | 2.8 | ||
| Intraday variation (RSD%, n = 15) | 6.9 | 7.4 | 5.8 | 3.9 | ||
| Accuracy (% ± SD, n = 20) | 104.7 (±9) | 92.5 (±9.1) | 98.3 (±7.9) | 97.3 (±4.0) | ||
| Chad positioning (RSD%, n = 5; hematocrit = 0.41) | 12.7 | 14.6 | 18.4 | |||
a
SD, standard deviation; RSD, residual standard deviation.
b
Internal standard.
c
Protein binding at a CFX concentration of 500 mg/liter was 63.5% (±0.5%).