Figure 1.

Mirror plots of observed MSMS spectra for biomarker 1 in a patient sample vs. an HACA standard in H₂O (1a) as well as biomarker 2 in a patient sample vs. an L-dopa standard in H₂O (1b). The intensity is arbitrary and was set to a value of 100. (1a) The m/z 148.0967 is the detected m/z of the molecular ion [C₆H₁₃NO₃+H]⁺, whereas m/z 85.0673 represents the base peak. All peaks aligned, and no fragment had a mass deviation above 5 ppm. (1b) The m/z 198.0764 is the detected m/z of the molecular ion [C₉H₁₁NO₄+H]⁺. Some peaks aligned with a mass deviation below 5 ppm, but the majority did not. Of note: The RT of C₉H₁₁NO₄ was 6.412 min, whereas the RT of L-dopa was 3.498.