Table 4.
Average intra-day and inter-day repeatability, and recovery (%) results obtained for each of the techniques studied. The concentration levels tested were as follows: for GC-EI-MS, L (low) = 1 ng/L, M (medium) = 10 ng/L, and H (high) = 100 ng/L; for GC-NCI-MS, L = 0.1 ng/L, M = 1 ng/L, and H = 10 ng/L; and for GC-EI-MS/MS, L = 0.01 ng/L, M-L = 0.1 ng/L, M-H = 1 ng/L, and H = 10 ng/L
| GC-EI-MS | GC-NCI-MS | GC-EI-MS/MS | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| L | M | H | L | M | H | L | M-L | M-H | H | |
| Intra-day repeatability (%, n = 9) | 7.1 | 7.8 | 5.2 | 5.6 | 5.5 | 3.7 | 12 | 4.0 | 2.8 | 2.1 |
| Intra-day repeatability (%, n = 9)* | 3.8 | 5.7 | 2.0 | 3.9 | 2.9 | 1.6 | 10.3 | 3.5 | 1.5 | 1.0 |
| Inter-day repeatability (%, n = 3) | 25 | 15 | 7.7 | 13 | 27 | 24 | 15 | 16 | 21 | 15 |
| Inter-day repeatability (%, n = 3)* | 12.6 | 8.7 | 4.5 | 5.3 | 7.4 | 2.9 | 13.2 | 9.7 | 9.6 | 7.7 |
| Recovery (%, n = 9) | 102 | 104 | 96 | 83 | 94 | 80 | 92 | 89 | 88 | 80 |
*Results obtained after internal standard-equivalent correction (explained in SI)