Table 4.
Quality assessment of the quantification on the triple quadrupole 3200QTrap® mass spectrometer (three days, single laboratory). [M + H]+ ions were 692 m/z and 694 m/z for SPX-1 and PnTX-G respectively. Product ions monitored were 674 m/z, 444 m/z and 164 m/z for SPX-1 (MRM1 as the quantifier, MRM2 and MRM3 as the qualifiers respectively); and 676 m/z, 458 m/z and 164 m/z for PnTX-G (MRM1, MRM2 and MRM3 respectively). Product ion ratios were calculated as the relative area (in percentage) of the qualifier MRM2 compared to the area of the quantifier MRM1. Variations in product ion ratios in mussels and oysters represent the difference (in percentage) between product ion rations measured in metanolic standard solutions and in spiked samples of mussels and oysters. LODs and LOQs in mussels were not trustable because the spiked sample was not completely blank. Later analysis on a PnTX-G free mussel sample had an LOD = 0.2 μg/kg and LOQ = 0.3 μg/kg (different methodology for limits calculation, see Results and Discussion and Experimental Section).
| SPX-1 | PnTX-G | ||
|---|---|---|---|
| Linearity range (ng/mL) (n = 15) | 2.5–50 | 2.5–50 | |
| RT (average, n = 75) | 6.33 | 7.36 | |
| % drift | 0.3 | 0.2 | |
| Product ion ratios (%) (n = 30) | Area MRM2/Area MRM1 | 40.7 | 77.1 |
| % variation in mussels | −1.0% | 0.3% | |
| % variation in oysters | −4.9% | 0.1% | |
| Recovery (%) (n = 9) | Mussel | 91.6 | 77.6 |
| Oyster | 81.0 | 66.6 | |
| Intra-day precision (RSDr) (%) (n = 9) | Mussel | 2.6 | 2.9 |
| Oyster | 3.1 | 2.5 | |
| Inter-day precision (RSDR) (%) (n = 9) | Mussel | 7.0 | 6.8 |
| Oyster | 7.1 | 6.2 | |
| LOQ (μg/kg) (n = 3) | Mussel | 19.6 | 56.1 |
| Oyster | 0.7 | 0.9 | |
| LOD (μg/kg) (n = 3) | Mussel | 5.5 | 10.8 |
| Oyster | 1.1 | 0.5 | |