The samples were extracted using a single extraction with 400 µl of methanol, containing the recovery standards: tridecanoic acid, fluorophenylglycine, chlorophenylalanine and d6-cholesterol.
The samples were extracted by solid-phase extraction (SPE) using a Rapid Trace (Caliper Life Science, Hopkinton, MA) modular SPE system.
The samples were extracted by solid phase extraction (SPE) using the Rapid Trace modular SPE work station (Caliper Life Sciences, Hopkinton, MA) for automation.
For the water extraction, the samples were extracted on a rocker incubator (Shanghai Yuejin Medical Instrument Factory, Shanghai, China) at room temperature for 120 min.
After spiking, the samples were extracted by means of Soxhlet extraction using a mixture of appropriate polar and non-polar solvents for ultratrace-analyses (e.g. hexane/acetone).
After spiking, the samples were extracted by means of ultrasonic extraction with appropriate polar solvents (e.g. methanol) for ultratrace-analyses (e.g. nanograde).
Briefly, the samples were extracted using 100 μL of extraction buffer and resuspended by pipetting gently.
The samples were extracted utilizing a pressurized fluid extraction (Accelerated Solvent Extractor, Dionex ASE-300) with a mixture of acetone and hexane (1 1, v/v).
The samples were extracted onto a 500-mg C18 solid-phase extraction column and eluted using 2 × 50 mL DCM.
The samples were extracted using the Rapid Trace (Caliper Life Sciences, Hopkinton, MA) modular solid phase extraction (SPE) system.
The samples were extracted from out-of-service equipment.
