List of the tested metabolites and drugs. A sample mix was spotted on COC slides and eluted with the extraction interface into the LC-MS. For comparison, the same sample mix was directly injected into the LC-MS instrument. The samples were measured in full scan mode. Additional sensitivity could be obtained by measuring in a targeted MRM mode. Retention times as well as the limit of detection (LOD) for directly injected samples and samples eluted from the slide are shown. A signal-to-noise ratio of three was used to estimate LOD. The log P value is a measure of a compound's lipophilicity or hydrophobicity. The tested molecules are spread across a broad range of log P values.
| Compound | [M + H]+ | log P | Concentration [μg mL−1] | Retention time [min] | LOD [pg] | ||
|---|---|---|---|---|---|---|---|
| Injected | Slide | Injected | Slide | ||||
| Alanine | 90.0544 | −2.85 | 0.488 | 0.44 | 0.67 | 24.40 | 24.40 |
| Aspartate | 134.0442 | −3.89 | 0.192 | 0.45 | 0.67 | 34.80 | 9.70 |
| Glutamic acid | 148.0599 | −3.69 | 0.497 | 0.46 | 0.68 | 24.84 | 24.90 |
| Valine | 118.0857 | −2.26 | 0.250 | 0.67 | 0.85 | 12.50 | 12.50 |
| Glutamine | 147.0759 | −3.64 | 0.492 | 0.68 | 0.67 | 24.25 | 24.60 |
| Nicotine | 163.1224 | 1.10 | 0.101 | 0.83 | 0.83 | 5.05 | 5.05 |
| Adenosine | 268.1035 | −1.20 | 0.789 | 2.26 | — | 39.40 | — |
| Phenylalanine | 166.0857 | −1.38 | 0.410 | 3.21 | — | 24.60 | — |
| Acetaminophen | 152.0701 | 0.46 | 0.392 | 4.45 | 4.55 | 39.20 | 19.60 |
| Sulfadimethoxine | 311.0803 | 1.08 | 0.725 | 6.92 | 7.02 | 36.25 | 36.30 |
| Carbamazepine | 237.1017 | 2.30 | 0.153 | 7.47 | 7.55 | 30.60 | 7.65 |
| Testosteron | 289.2157 | 3.32 | 0.112 | 8.56 | 8.63 | 56.00 | 22.40 |
| Diclofenac | 296.0234 | 3.90 | 0.228 | 9.48 | 9.57 | 22.80 | 91.20 |