Table 3.
Cathinone stability in biological matrices.
| Analyte | Solvent | Storage temperature (°C) | % Difference between days 0 and 30 | p-value | Stability call | First unstable day of analysis |
|---|---|---|---|---|---|---|
| Mephedrone | Blood | 20 | 96.5 ± 0.3% | 3.56E-09 | Unstable | Day 7 |
| 4 | 24.0 ± 2.1% | 5.42E-03 | Unstable | Day 14 | ||
| −20 | 25.5 ± 7.8% | 3.33E-03 | Unstable | Day 14 | ||
| Urine | 20 | 40.8 ± 1.6% | 5.24E-05 | Unstable | Day 7 | |
| 4 | 0.1 ± 5.2% | 1.50E-01 | Stable | – | ||
| −20 | 7.0 ± 8.4% | 3.48E-02 | Stable | – | ||
| Naphyrone | Blood | 20 | 98.8 ± 0.2% | 1.12E-09 | Unstable | Day 3 |
| 4 | 91.1 ± 2.2% | 6.44E-08 | Unstable | Day 3 | ||
| −20 | 25.4 ± 9.1% | 7.65E-03 | Unstable | Day 30 | ||
| Urine | 20 | 97.6 ± 0.6% | 2.44E-08 | Unstable | Day 30 | |
| 4 | 0.4 ± 3.1% | 4.21E-01 | Stable | – | ||
| −20 | 2.7 ± 4.4% | 2.65E-01 | Stable | – | ||
| MDPV | Blood | 20 | 45.7 ± 3.2% | 1.32E-03 | Unstable | Day 30 |
| 4 | 4.9 ± 12.8% | 3.72E-01 | Stable | – | ||
| −20 | 9.4 ± 3.2% | 3.39E-01 | Stable | – | ||
| Urine | 20 | 8.0 ± 5.8% | 5.26E-01 | Stable | – | |
| 4 | 14.7 ± 8.3% | 7.32E-02 | Stable | – | ||
| −20 | 8.6 ± 1.2% | 8.23E-01 | Stable | – | ||
| α-PVP | Blood | 20 | 72.3 ± 1.9% | 6.75E-08 | Unstable | Day 14 |
| 4 | 8.0 ± 1.2% | 9.16E-03 | Stable | – | ||
| −20 | 6.6 ± 2.8% | 3.17E-03 | Stable | – | ||
| Urine | 20 | 12.4 ± 2.7% | 4.61E-05 | Stable | – | |
| 4 | 12.4 ± 2.0% | 2.40E-02 | Stable | |||
| −20 | 14.7 ± 4.6% | 9.14E-04 | Stable | – |
Bold values indicate instability criteria were met (i.e., % change in concentration >= 20 and/or p < 0.05).