Fig. 1

GC-MS quantification of metabolites derivatised by methoximation-acetylation-butylation. The volume of derivatised standard mixture was 10 μl, the injection volume was 1 μl splitless, and ions were monitored with a dwell time of 50 ms. Peaks areas were normalised to internal standard succinic acid-d6. a GC chromatogram generated in scan mode for equimolar (2 mM) standard of pyruvate, lactate and glucose. Pyurvate and lactate peaks are shown as ions 142 and 115, respectively (left zoom-in panel). The methoxime and nitrile derivatives of glucose pentaacetate peaks are shown as ions 331 and 314, respectively (right zoom-in panel). b Equimolar calibration curves for pyruvate, lactate and glucose. Duplicate injection of standards between 0.125 and 2 mM. c Similar calibration curves with concentrations set at expect medium ranges: 0.25–2.0 mM for pyruvate, 1.25–10 mM for lactate, and 2.5–20 mM for glucose