Table 3.
Lower limit of quantification (LLOQ), calibration curve, correlation coefficient (R2), precision, and accuracy of all analytes in urine by LC-MS/MS.
| Analytes | LLOQ (ng/mL) | Calibration curve (ng/mL) | R 2 | Intraday precision (n = 5, %CV) |
Interday precision (n = 5, %CV) |
Accuracy (%) (n = 5) |
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 25 ng/mL | 50 ng/mL | 75 ng/mL | 25 ng/mL | 50 ng/mL | 75 ng/mL | 25 ng/mL | 50 ng/mL | 75 ng/mL | ||||
| Mephedrone | 6.3 | 6.3–100.0 | 0.9969 | 5.66 | 3.85 | 3.08 | 2.23 | 4.16 | 2.31 | 100.00 | 101.20 | 108.80 |
| Butylone | 6.3 | 6.3–100.0 | 0.9991 | 1.80 | 3.27 | 4.37 | 6.63 | 1.90 | 5.81 | 99.20 | 100.40 | 97.80 |
| Pentylone | 6.3 | 6.3–100.0 | 0.9984 | 2.83 | 3.59 | 3.24 | 4.87 | 9.21 | 4.66 | 100.00 | 99.60 | 98.40 |
| Eutylone | 3.1 | 3.1–100.0 | 0.9986 | 4.90 | 2.30 | 3.09 | 4.83 | 3.03 | 5.20 | 100.00 | 96.20 | 98.40 |
| Ephylone | 6.3 | 6.3–100.0 | 0.9994 | 3.64 | 2.95 | 3.37 | 8.33 | 9.15 | 9.30 | 98.40 | 100.40 | 98.40 |
| 4-MEAPP | 3.1 | 3.1–100.0 | 0.9991 | 3.37 | 2.83 | 3.75 | 4.53 | 7.35 | 4.04 | 99.20 | 100.00 | 97.33 |
| PMA | 6.3 | 6.3–100.0 | 0.9990 | 4.67 | 1.08 | 1.20 | 5.48 | 9.58 | 3.04 | 97.60 | 101.20 | 99.47 |
| PMMA | 6.3 | 6.3–100.0 | 0.9997 | 2.23 | 1.77 | 0.94 | 8.70 | 6.96 | 5.24 | 98.40 | 100.80 | 100.00 |
| DCK | 6.3 | 6.3–100.0 | 0.9997 | 0.89 | 0.90 | 2.00 | 3.52 | 3.04 | 4.34 | 101.60 | 99.96 | 98.93 |
| 2-FDCK | 3.1 | 3.1–100.0 | 0.9994 | 2.83 | 2.60 | 2.87 | 2.23 | 4.66 | 3.56 | 100.00 | 101.87 | 98.67 |
LC-MS/MS: liquid chromatography-tandem mass spectrometry; mephedrone: 4-methylmethcathinone; ephylone: N-ethylpentylone; 4-MEAPP: 4-methyl-α-ethylaminopentiophenone; PMA: para-methoxyamphetamine; PMMA: para-methoxymethamphetamine; DCK: deschloroketamine; 2-FDCK: 2-fluorodeschloroketamine; CV: coefficient of variation.