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Plasma peptides are widely used in clinical diagnosis and therapy monitoring. Our aim was an efficient system development for the enrichment of small, low abundant peptides from plasma by robotized sample preparation. The automation of SPE yields additional time saving and improves system robustness and repeatability. Automation is based on combining a Waters SPE kit with Oasis HLB sorbent and a multichannel liquid handling workstation with cheap commercially available electronic devices such as a programmable logic controller (PLC) and an AVR controller. Reversed phase nano liquid chromatography coupled with a sensitive quadrupole time of flight mass spectrometer (QTOF MS) was used for the quantitative determination of somatostatin (SST). We quantified SST from mouse plasma, where lower limit of detection (LLOD) and lower limit of quantification (LLOQ) were 2.5 and 8.3 fmol/ml, respectively. We investigated linearity of response, accuracy, precision, recovery, reproducibility and stability of SST during both short-term sample processing and long-term storage. This method allows reliable quantification of plasma peptides. The developed automated sample preparation solid phase extraction method can be easily and conveniently adopted for different volumes and amounts of sample in routine analysis using controlled vacuum. The highest advantage is enhanced reproducibility, which makes it suitable for the investigations of large sample cohorts in clinical studies.

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