## Materials and Methods
### Automated Sample Preparation  
All sample preparation steps were performed using the Biomek i7 Workstation. The work steps for the serum, saliva and urine matrices are summarized in Figure 2. A separate method was created for each matrix, but the basis of the three methods is a solid-phase extraction using the Strata X-C uElution Plate (Phenomenex, Torrance, CA, USA). Saliva samples were loaded directly onto the SPE plate without further sample preparation methods. For the purification of urine samples, additional hydrolysis was performed prior to SPE to cleave off the glucuronide conjugate, whereas, for serum samples, protein precipitation was performed to precipitate the proteins present in the serum. For protein precipitation, 500 \(\mu\)L MeOH from the Self Refilling Quarter Reservoir (see Figure 1) and 200 \(\mu\)L 0.2 M ZnSO4 to improve protein aggregation from an additional 40 mL reservoir are pipetted with the Span-8 Pipetting Head into 1.5 mL glass vials provided for protein precipitation (see Figure 2). Subsequently, the aluminum adapter was transported from the Static Peltier ALP to the 3D Tilting ALP, which was tilted 10\({}^{\circ}\) and the standard was aspirated. The aim of tilting was to enable the robot to empty vials with valuable liquids as completely as possible. An alternative was 1.5 mL High Recovery Vials (Agilent Technologies, Santa Clara, CA, USA), which were used in the urine and saliva method to expedite the pipetting process but are only suitable to provide small sample volumes (in our case 50 \(\mu\)L internal standard). The serum sample was added last, to allow rapid in-pipette mixing during the previous transfer steps without clogging. For optimal mixing and dissolution of plasma protein-bound analytes, the vials are shaken on the Shake Peltier ALP for 1 min at 1500 rpm orbital rotation; then transported to the centrifuge and centrifuged for 4 min at 3000 rpm. At the same time, the solid phase extraction cycle starts with the conditioning and equilibration of the sorbent bed, so that after centrifugation the supernatant can be removed directly and transferred to the SPE plates. A similar procedure was used for basic hydrolysis in the preparation of urine samples. After adding 800 \(\mu\)L urine, 50 \(\mu\)L internal standard and 20 \(\mu\)L NaOH and loading the incubator with the hydrolytic sample filled Greiner 48 well plate, the SPE process starts during the 15-min incubation time. At the end of the incubation at 60 \({}^{\circ}\)C, the 48 well Greiner plate was removed by the second gripper arm of the Biomek i7 workstation and the basic hydrolysate was neutralized by the addition of 195 \(\mu\)L of glacial acetic acid, which was stored in the refrigerated aluminum adapter on the Static Peltier ALP, as were the standards. For saliva,50 \(\mu\)L of internal standard was added directly to the already applied 400 \(\mu\)L saliva sample in the wells of the Strata X-C \(\mu\)Elution Plate. After the Load step, the sorbent was washed in two steps each with 200 \(\mu\)L of 0.1 N Acetic Acid in H\({}_{2}\)O and 200 \(\mu\)L of 0.1 N Acetic Acid in acetonitrile. The purified analytes in the sorbent bed were eluted by a 2-fold transfer of 2% Acetic Acid in acetonitrile with 25 \(\mu\)L each for serum samples and 55 \(\mu\)L for saliva and urine samples to increase recovery. Between all liquid transfers, positive pressure is applied to the Strata X-C \(\mu\)Elution plate using the Positive Pressure Unit V4. Figure 2: Sample Preparation Process. In preparation for injection with the LC-MS autosampler, samples eluted into an MTP plate were transferred to 1.5 mL glass vials with micro vial inserts to complete sample preparation, containing either 25 \(\upmu\)L (serum) or 40 \(\upmu\)L (saliva; urine) eluate. Finally, water was added to the eluate to correspond with the mobile phase.