Table 2: NMR integration regions and investigated linear concentration ranges.

CompoundNMR rangeWorking range (mg/kg)

HMF9.43–9.47 ppm (singlet)20–600
Formic acid8.44–8.47 ppm (singlet)40–1400
Phthalic acid7.53–7.48 ppm (multiplet)30–900
Fumaric acid6.53–6.55 ppm (singlet)20–670
Pyruvic acid6.42–6.45 ppm (singlet)180–5000
L(+)-rhamnose5.13–5.09 ppm (doublet)160–2500
Glucose4.63–4.65 ppm (singlet)13–43000
Arabinose4.52–4.54 ppm (singlet)40–1200
L(+)-tartaric acid4.32–4.35 (singlet)90–2600
Fructose 4.14–4.08 (doublet)11–46000
Malic acid2.73–2.70 (two singlets)30–1000
Citric acid2.69–2.68 (singlet)40–1300
Succinic acid2.50–2.52 (singlet)10–800